RCAT RCAT-1A Revision A3 System Manual

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RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

RCAT

Robotic System Control Board

Serious Power for the Serious Designer

System designer’s manual

Current Version: RCAT-1A Revision A3

Robot Circuits, LLC

sales@robotcircuits.com support@robotcircuits.com

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Table of Contents

RCAT ................................................................................................................................................................................ 1

Robotic System Control Board ...................................................................................................................................... 1

Introduction ..................................................................................................................................................................... 5

So what in the world does “RCAT™”mean? .................................................................................................................. 5

What are we trying to do that other boards cannot? .................................................................................................... 6

RCAT™ Board specifics ..................................................................................................................................................... 8

Power System .............................................................................................................................................................. 8

Schematic ................................................................................................................................................................ 8

Major Subsystems .......................................................................................................................................................... 10

Subsystems – Detailed discussion .................................................................................................................................. 16

LED ............................................................................................................................................................................ 16

Configuration ......................................................................................................................................................... 16

Control ................................................................................................................................................................... 16

Schematic .............................................................................................................................................................. 16

System Clock .............................................................................................................................................................. 17

Schematic .............................................................................................................................................................. 17

Notes ..................................................................................................................................................................... 17

Extended Static RAM .................................................................................................................................................. 17

Schematic .............................................................................................................................................................. 17

Notes ..................................................................................................................................................................... 18

TWI Interface ............................................................................................................................................................. 18

Schematic .............................................................................................................................................................. 18

Notes ..................................................................................................................................................................... 19

1M-bit serial EEPROM ................................................................................................................................................ 19

Accelerometer ........................................................................................................................................................... 19

SPI Interface ............................................................................................................................................................... 20

Schematic .............................................................................................................................................................. 20

ADC AREF ................................................................................................................................................................... 21

Schematic .............................................................................................................................................................. 21

JTAG .......................................................................................................................................................................... 21

Schematic .............................................................................................................................................................. 21

Mosfet Drivers ........................................................................................................................................................... 22

Schematic .............................................................................................................................................................. 22

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Alternatives for controlling the mosfets ................................................................................................................. 24

Direct I/O Access ........................................................................................................................................................ 25

Primary I/O Connector ........................................................................................................................................... 26

SPI Connector ......................................................................................................................................................... 27

USART 0 ................................................................................................................................................................. 27

USART 2 Port – J14 and J7 ...................................................................................................................................... 27

3.3 Volt Input/Output ............................................................................................................................................. 28

USART 3 Port – J8 ................................................................................................................................................... 30

Schematic .............................................................................................................................................................. 31

USART 1 Port – J6 ................................................................................................................................................... 32

Schematic .............................................................................................................................................................. 32

Final comments about USART direct connections ....................................................................................................... 34

Summary of direct access ports .................................................................................................................................. 34

USARTS, and Serial Communications Interfaces ............................................................................................................. 35

RS422/485 Interface ...................................................................................................................................................... 40

Schematic .................................................................................................................................................................. 40

Free RS232 Channel ....................................................................................................................................................... 41

Ethernet System ............................................................................................................................................................ 41

Programming IDE (interactive Development Environment) ........................................................................................ 43

RCAT™ Startup Solution Software .............................................................................................................................. 43

In-Circuit Emulator ..................................................................................................................................................... 43

Demonstration Software ................................................................................................................................................ 44

RCAT™ Specifications ..................................................................................................................................................... 45

Schematic Diagram ........................................................................................................................................................ 46

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Warranties

1. (a) Robot Circuits, LLC warrants for a period of one (1) year from the date of sale that the RCAT™ Control Board conforms to and will

perform according to the Specifications.

(b) Robot Circuits, LLC shall not be liable for any defects caused by abuse, neglect, improper use, installation, or modification of the RCAT™, nor as a result of any customer design or use involving the attachment of any devices, testing apparatus, or other hardware.

(c) Robot Circuits, LLC shall not be liable for any damage or harm, bodily or other, resulting from specifications, designs documentation, or instructions, verbal or written, not produced by Robot Circuits, LLC.

2. If the RCAT™ Control Board fails to perform to the warranty set forth in section 1 above, then Robot Circuits’ sole liability shall be to

effect the replacement of the board. Replacement board shall be covered under the warranty for the full warranty period.

3. THIS LIMITED WARRANTY IS THE END-USER’S SOLE AND EXCLUSIVE REMEDY AGAINST ROBOT CIRCUITS, LLC WHERE PERMITTED BY LAW.

AND SUBJECT TO SECTION (8). EXCEPT AS SET FORTH ABOVE, PRODUCTS ARE PROVIDED “AS IS” AND “WITH ALL FAULTS”. ROBOT CIRCUITS, LLC DISCLAIMS ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, REGARDING PRODUCTS, INCLUDING, BUT NOT LIMITED TO, ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

4. The Customer agrees that prior to using any systems that include Robot Circuits, LLC products, the Customer will test such systems and

the functionality of the products as used in such systems. Robot Circuits, LLC may provide technical, applications or design advice, quality characterization, reliability data or other services. The Customer acknowledges and agrees that providing these services shall not expand or otherwise alter Robot Circuits, LLC’s warranties, as set forth above, and that no additional obligations or liabilities shall arise from Robot Circuits, LLC providing such services.

5. Robot Circuits, LLC products are not authorized for use in safety-critical applications where a failure of the Robot Circuits, LLC product

would reasonably be expected to cause severe personal injury or death. Safety-critical applications include, without limitation, life support devices and systems, equipment or systems for the operation of nuclear facilities and weapons systems. Robot Circuits, LLC products are neither designed nor intended for use in military or aerospace applications or environments, nor for automotive applications or the automotive environment. The Customer acknowledges and agrees that any such use of Robot Circuits, LLC products is solely at the Customer’s risk, and that the Customer is solely responsible for compliance with all legal and regulatory requirements in connection with such use.

6. The Customer acknowledges and agrees that the Customer is solely responsible for compliance with all legal, regulatory and safety-

related requirements concerning the products and any use of Robot Circuits, LLC products in the Customer’s applications, not-withstanding any applications-related information or support that may be provided by Robot Circuits, LLC.

7. In no event shall Robot Circuits, LLC be liable to the Customer or any third parties for any special, collateral, indirect, punitive, incidental,

consequential or exemplary damages in connection with or arising out of the products provided hereunder, regardless of whether Robot Circuits, LLC has been advised of the possibility of such damages. This section will survive the termination of the warranty period.

8. Robot Circuits, LLC may make changes to specifications and product descriptions at any time, without notice. The product information on

the Robot Circuits Web Site is subject to change without notice.

9. Statutory laws. *

(i) some countries, regions, states or provinces do not allow the exclusion or limitation of remedies or of incidental, punitive, or consequential damages, or the applicable time periods, so the above limitations or exclusions may not apply. (ii) except to the extent lawfully permitted, this limited warranty does not exclude, restrict or modify statutory rights applicable to where the product is sold but, rather, is in addition to these rights. (*) European Consumer Centres provide information on EU-wide consumer laws as well as consumer laws for specific countries:

http://ec.europa.eu/consumers/ecc/contact_en.htm

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Introduction

Welcome to the world of RCAT™ – We here at Robot Circuits believe you will find that the RCAT™ control board is simply the most versatile, powerful, easy to use, and cost-effective control board on the market today.

This manual will introduce you to the many features that are resident on the board and will guide you through the process of configuring the board for your specific application. But before we get started, please allow us to give you a little background on why we even bothered bringing this board into existence…

First things first …

So what in the world does “RCAT™”mean?

Well, RCAT™ is an acronym for:

Robotic Controller based on the ATMega™ 2560 microcontroller by Atmel Corporation.

The RCAT™ is, put quite simply, one of the most powerful low-cost single board Microcontroller boards available on the robotic enthusiast market today.

Consider this summary of the RCAT’s features:

 The RCAT™ is based on the Atmel ATMega™ 2560 Microcontroller which features

o 256K of Program Flash ROM o 4K internal EEPROM o 8K internal SRAM o 4 High-speed USARTS o SPI port o TWI (I2C) Interface o Watchdog timer o Many more features that you can view at Atmel.com

 Direct access to 48 of the ATMega™ 2560’s most crucial I/O ports  Two 30V/400mA Mosfet drivers  128K External Static RAM (directly addressable by the ATMega™ 2560 as 2 pages of 64K each)  Most communications interfaces feature selectable as 3.3V/5V  Diagnostic 3-color LED  1M-bit Serial EEPROM  14 different communications devices/electrical interfaces/protocols/voltage levels  Power switch connection  Selectable onboard Vcc regulation or 5Vdc primary power input  On-board 3.3Vdc voltage regulator  Easy connection to Network via Serial-Ethernet Server (not included)  On-board USB connector with bridge to serial I/O system  3 channels of RS-232 RX/TX  ADXL345 3-Axis Accelerometer for fast, accurate measurement of inertial and attitudinal situations  Connectors oriented for easy connection to sonars, servo’s or any device requiring typical Gnd/Vcc/Signal

connections

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

 JTAG connector for instant connection to in-circuit emulators such as Atmel’s ATATMEL-ICE™  Flawless functioning with Atmel AVR Studio (current version 7.0)  Demo code included – contains full AVR Studio solutions featuring driver examples for the RCAT board devices as

well as several peripherals. Code is implemented using freeRTOS, a powerful open-source preemptive multitasking operating system, with XRAM configured as heap space, fully functioning dynamic memory management, and demo modules each implemented as scheduled tasks. Best of all, it works and doesn’t take 2 weeks of study just to get installed and running on your system!

One of the major features of the RCAT board is its rich array of communications options. All totaled there are 14 different serial interfaces available. Although only a subset of these is available at any one time, the flexibility of the communications system allows you to interface with almost any serial device you can imagine. The 14 interfaces include:

USART 0: USB 2.0 RS232 RS422/485

USART 1: Direct Connection at 5V Indirect Connection at 3.3V Indirect Connection at 3.3V to Ethernet Converter Interface Connector

USART 2: Direct Connection at 5V – Full Duplex

Direct Connection at 5V – Half Duplex Indirect Connection at 3.3V – Full Duplex Indirect Connection at 3.3V – Half Duplex RS232

USART 3: Direct Connection at 5V Indirect Connection at 3.3V

Uncommitted RS232 (1 channel featuring TX-IN, TX-OUT, RX-IN and RX-OUT access to Transceiver)

What are we trying to do that other boards cannot?

We at Robot Circuits are robotic system designers ourselves. Almost daily we live through the chore of selecting hardware that is:

 easy to use  has the most on-board power without having to buy this shield or that add-on just to get basic needs that are

common with almost every design

 offers a sufficient amount of direct connection to the CPU  is a no-brainer to connect to ICE equipment  is fast  has high-current drivers on-board

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

 includes lots of on-board communications capability (possibly our number one requirement)  is affordable  comes with good documentation  is easy to configure and get running for OUR APPLICATION  comes with actual working examples of useful code

It is not difficult to find project boards on the market that are little more than breakout boards, marketed with a plethora of add-on boards and so-called “shields”. But what about us who need, say, a board that already comes STANDARD with extended RAM so that we can implement dynamic memory allocation, or realtime O/S capability?

Sometimes we with real jobs and real deadlines just don’t have time or patience to shop around for what should be “the basics”.

So, we designed the RCAT™ as an end-run around these issues. The RCAT™ comes STANDARD with:

 128K of extended static RAM (divided into two 64K pages that are switchable via an I/O port)  An on-board ADXL345 accelerometer for easy inertial and attitudinal measurement  An onboard three-channel RS-232 transceiver  An onboard RS422/485 interface  An onboard USB bridge  An on board 1M-bit non-volatile RAM  Two onboard 30V/400mA mosfet drivers  A 3.3Vdc Voltage regulator with access to the outside world

In addition, we provide COMPLETE, FUNCTIONAL, LOAD-AND-RUN demonstration software that you can use as a

foundation for your application or just for educational purposes. This software is written with Atmel’s Atmel Studio™ in

mind. All that is required to get you up and running is the RCAT™ control board, a connection to an appropriate power source, a PC capable of connecting to an ICE (in-circuit-emulator), an ICE (in-circuit-emulator) like the ATATMEL-ICE™, and a download of Atmel’s free Atmel Studio™ IDE. Once installed, you can simply load our project file and begin running.

Of all the things that have irritated us at Robot Circuits over the years is downloading somebody’s “demo” code, only to find that it is useless unless we are using some compiler or ide that is mainstream only to super-geeks, and even then having to study, study, study just to figure out how to set paths, and compiler flags, and this and that and you name it.

Then – to find that the code doesn’t even do what we needed it to do.

We work in the real world and we needed real information that was relevant to solving real problems.

THAT is what we are striving for at Robot Circuits – to provide you with a “no-games”, professional-grade robotic control platform that can actually DO SOMETHING!

We hope you find that we have accomplished this by helping you to achieve your goals.

Now…..let’s talk tech…

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

RCAT™ Board specifics

Power System

The power input schematic is shown in Figure 1 below:

Schemat ic

Figure 1

The power input connector, J3, allows several configurations and options for power to the board. The simplest and most preferable is shown in Figure 2. In this configuration, a regulated 5Vdc is fed to J3 at pin 1. With JP3 installed, this routes the 5Vdc immediately back out J3 on pins 2 and 5. Pin 2 is a redundant output where you can daisy-chain the 5Vdc to other devices if desired. Pin 5 is meant for use when you need to switch the board itself on and off (independent of the power supply). In this case, as show in Figure 2, you can place a switch between pins 5 and 6:

Figure 2

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Optionally, you can connect a shorting wire in place of the switch if you will be controlling the RCAT™ power from the power supply itself.

The RCAT™ can be fitted with an optional onboard 5Vdc regulator (U4) for cases where you do not have 5Vdc already available. As shipped the RCAT™ does not include this regulator. This is something you would add yourself. The chip

required is the LM7805C – TO220 and can be purchased here. Cost is around 68 cents. Figure 3 shows the land patterns where this chip installs.

Figure 3

The RCAT™ draws about 500mA when it isn’t driving external peripherals. When driving other peripheral devices such as

devices utilizing the full capability of the mosfets (which can draw up to 400mA each), and sonar ranging modules, etc., the current requirements increase accordingly. The LM7805 is good for 1A which will (with adequate heatsinking) suffice for moderate current requirements, but for most applications we recommend using an external 5Vdc supply rated for 3A which should cover the most extreme cases. Of course, your particular design requirements will drive this decision.

As shown in Figure 2, there exists an onboard 3.3Vdc regulator (U5) that supplies power to the onboard devices requiring 3.3Vdc. These include the accelerometer (about 10mA max), the USB bridge chip (about 26mA max), and the 5V to 3.3V voltage translators (about 100mA max) for a total consumption around 136mA. The regulator employed is a LM2937-3.3 that is capable of up to 500mA. Under normal conditions, 136mA does not require a heat sink. However, if you plan to tap into the 3.3Vdc to power external devices you may need to fit U5 with an appropriate heat sink – not doing so can damage the RCAT™ and will void your warranty.

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Major Subsystems

The RCAT™ control board comprises several major subsystems. Some of these subsystems are broken out to connectors on the board for access by external user hardware. Others are not. Still others have access to the outside world through interim circuitry. For example, the extended RAM subsystem is not broken out for external access. This means that CPU ports PA0 through PA7, PC0 through PC7, PG0 through PG2 and finally PJ7 are dedicated to this subsystem and thus are not brought out to external connection points. Consider the extended RAM subsystem schematic:

Figure 4

We call such subsystems “dedicated” in that they use CPU ports fully dedicated to nothing other than the subsystem.

As mentioned above, other subsystems have breakout points on various connectors. These may be “direct” connections

to the CPU or they may be “indirect” connections. An example of an “indirect” subsystem is the USB interface subsystem

shown here:

Figure 5

As you can see, CPU ports RXD0(PE0) and TXD0(PE1) connect to the USB bridge chip and then to the external world through the bridge. Although you have “access” to the ports, it is “indirect” through an onboard device (the CP2102 USB chip).

The “direct” access subsystem consists of 37 connections broken out on J5 as shown here:

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Figure 6

Other ports that provide direct access are presented at other connectors that are configured for use by the alternate port purposes. For example, connector J4 provides direct access to ports PF4, PF5, PF6, PF7 and the CPU reset input. However, J4 is laid-out for direct connection to an in circuit emulator for use by the CPU JTAG system:

Figure 7

If you are not using the JTAG interface, these connection points are available for your use.

With the exception of PL0 and PL1 (discussed later), each of these points connects to and only to the port as labeled on the connector. You are totally in control of these ports.

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Ports PL0 and PL1 are a special case. They are shared with the control of the mosfet driver subsystem shown here:

Figure 8

As shown in the diagram on the left, from the CPU chip, ports PL0 and PL1 are connected on the board to the gates of mosfets Q3 and Q4. However, they are also brought out to connector J5 via a pair of jumpers as shown in the right-hand diagram. This enables you to control the gates either from the CPU via software or externally, by configuring ports PL0 and/or PL1 as inputs, and installing JP28 and/or JP29, thus bringing connection to the gates out to J5.

The third and final type of subsystem on the RCAT™ board is what we call a “bussed” subsystem. The primary system of

this type is the two-wire-interface (TWI) subsystem. Consider the following schematic:

Figure 9

Here we can see that CPU ports SCL(PD0) and SDA(PD1) interface with the onboard 1M-bit serial EEPROM (U3). But then the ports are also connected to pullup resistors R5/R5 and then broken out for external access to J2 so that you have direct access to the TWI subsystem as well.

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

A complete list of all the subsystems on the RCAT™ is presented below:

Subsystem Name Type Access Connector Description And Associated Jumpers LED Dedicated N/A Onboard Green/Yellow LED controlled by ports

PL6 and PL7 System Clock Dedicated JP1 16MHz Crystal with XTAL1 disconnect via JP1 Extended Static RAM Dedicated N/A A Cypress Semiconductor CY7C1019D-10VXI

RAM chip is provided onboard that makes 128K

bytes of static RAM available to the CPU in two

pages of 64K bytes. Page selection is managed

via dedicated I/O port PJ7. The chip I/O reserves

CPU ports AD0-AD7, A8-A15, and PG0-PG2 for

its exclusive use. TWI Interface Bussed J2 Provides direct access to CPU ports PD0 and

PD1 (SCL/SDA) via J2 pins 8 and 6 respectively.

Resistors R4 and R5 pull these pins up to Vcc as

required by TWI. Two additional pins, J2/7 and

J2/5, provide access to the TWI bus through

bidirectional 3V level shifters for interfacing to

3V TWI devices. 1M-bit serial EEPROM Bussed J2 M24M01-RMN6TP serial EEPROM controllable

via CPU or external TWI at J2. See TWI details

above and EEPROM datasheet for details. Chip

write enable (/WC) is directly controlled by port

PD4 on CPU chip. This is not accessible outside

the CPU. Accelerometer Bussed/Direct J5, JP23, JP30 The onboard ADXL345 accelerometer chip

Interfaces with the CPU on the TWI bus. This

means that it can also be accessed by the

external TWI connector J2. Jumper JP23 is used

to select the device address and jumper JP30 is

used to enable/disable the device via its /CS

pin. The interrupt outputs (INT1 and INT2) are

brought out to the CPU at PE4 and PE5

respectively. These are also brought out to J5 at

the PE4/PE5 pins. See the accelerometer

section later in this document for schematic and

detailed usage directions. SPI Interface Direct J1 Direct access to Ports PB1, PB2, PB3, RST

J1 configured for use in Serial Peripheral

Interface (SPI) (See ATMega™ Manual for

details)

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Subsystem Name Type Access Connector Description And Associated Jumpers ADC AREF Direct J15 If an external AREF supply is desired for use in

the Analog-to-digital system, it may be injected

at J15 pin 1. Vcc and ground from the board are

also provided at J15/2 and J15/3 respectively.

See ADC details later in this document. JTAG Direct J4 J4 is laid-out for direct connection via a 5X2

dual-row header to ICE equipment such as the

ATATMEL-ICE™. If not used for this purpose,

direct access to Vcc, Gnd, ports PF4-PF7, and

the /RST pin are available for general purpose

use. Mosfet Drivers Direct J5, JP26-JP29 Two high-current mosfets enable driving loads

up to 30Vdc at up to 400mA each. On/off

control is determined by the installation of

jumpers JP28 and JP29. Loads are attached on

JP26 and JP27. When the control jumper(s) are

installed, on/off control can be achieved by

either the CPU on ports PL0 or PL1 or by

external control at J5 pins PL0_A and PL1_A. If

the jumpers are NOT installed, then control is

exclusively via the CPU under program control

and J5 PL0_A and PL1_A are not connected to

anything on the board. See schematics later in

the mosfets section for further details. USART 0 Indirect J9, J11, J16, USART0 can be configured for any one of the JP14, JP16, following :

JP18, JP19, RS232 (I/O available at J11) JP24, JP25 USB (I/O available at J9)

RS422/485 (I/O available at J16)

See USART0 configuration details later in this

document for schematic and jumper

configurations. USART 1 Direct/Indirect J6, J9, J12, USART1 can be configured for any one of the JP6, JP7 following :

RS232 (I/O available at J12)

Direct connection at 3.3Vdc (I/O available at J6)

Direct connection at 5Vdc (I/O available at J6)

USB available at J9

See USART1 configuration details later in this

document for schematic and jumper

configurations.

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Subsystem Name Type Access Connector Description And Associated Jumpers USART 2 Direct J7, J14 USART2 can be configured for any one of the JP5, JP10, JP11 following :

Direct full duplex connection at 3.3Vdc

Direct full connection at 5Vdc

Direct half duplex connection at 3.3Vdc

Direct half connection at 5Vdc

Full duplex mode I/O available at J7

Half duplex mode available at J14

See USART2 configuration details later in this

document for schematic and jumper

configurations. USART 3 Direct J8, USART3 can be configured for any one of the JP12, JP13 following :

Direct connection at 3.3Vdc (I/O available at J8)

Direct connection at 5Vdc (I/O available at J8)

See USART3 configuration details later in this

document for schematic and jumper

configurations. Power supply N/A J3, JP2, JP3, JP4 The RCAT™ board comes configured for

operation from a regulated 5Vdc 3Amp power

supply. It can also be configured for operation

from an unregulated input voltage of 7.5 to

35Vdc by installing an optional LM7805C

regulator in position U4. Please note that

adequate heat sinking is required if you choose

this option and install the regulator. It is up to

the user to provide adequate heat sink. The

RCAT™ has an onboard 3.3Vdc regulator for

powering the onboard chips and systems

requiring 3.3Vdc. This voltage is also available at

several points on the board for use by external

systems. It is incumbent upon the user to not

exceed current draw and to provide proper heat

sink if external 3.3V devices are connected.

Please see the datasheets for the LM2937-3.3

regulator chip for details and specs. Also note

that the 3.3Vdc provided by this chip is NOT the

same as the 3.3Vdc output that is made

available on the USB bridge chip U11.

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Bit

State

DDRL

6 1 DDRL

LED State

PL6

PL7

Off 1 1

Yellow

0 1 Green

1 0 Yel/Grn

Subsystems – Detailed discussion

In this section each of the above subsystems is discussed in more detail, including schematics to help you understand the subsystem design and hopefully guide you to an understanding of how to use each.

LED

The onboard LED is controlled by the CPU from ports PL6 and PL7. In order to use the LED, both of these ports should be configured as outputs through their associated Data Direction (DDR) registers.

Configuration

Table 1

Control

Schem atic

Table 2

Figure 10

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

System Clock

The onboard 16MHz crystal provides the CPU timing reference.

Schem atic

Figure 11

Notes

Although rare, it is possible to “brick” the ATMega™ chip by improperly setting clock values in the programming

apparatus and even sometimes, again, very rarely, as a result of improper voltages or signals being applied to numerous ports on the CPU. When that occurs, it is necessary to provide an externally generated clock to the CPU in order to recover. There are plenty of how-tos available online in the event you should brick your board. But one thing is always necessary – to inject an external clock into the XTAL1 input of the CPU. For this reason, JP1 is provided so that you can remove the jumper and connect your external clock to the CPU. Hopefully you will never need this, but in the event it happens, at least you won’t have to unsolder the crystal just to recover your board.

Extended Static RAM

Schem atic

Figure 12

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Notes

128Kbytes of external static RAM are available to be used by the CPU. The ATMega™ 2560 only directly addresses 64Kbytes. In order to make all 128Kbytes available, the RCAT™ board uses port PJ7 as address line

A16. The GCC compiler can be configured to utilize this RAM in a variety of ways. Please consult the documentation for the IDE to learn the various possibilities. However, in no case is native support for more than 64Kbytes provided, so you will need to manage the paging via your own code. For most applications, 64K is plenty of space, but the extra page is there if you need it.

The sample solution provided with your board configures most of page 1 of this RAM as heap and uses it in the dynamic allocation functions such as malloc().

The CPU ports that interface to this RAM are not available for any other purpose on the RCAT™.

TW I Interface

Sometimes referred to as I2C (Philips Semiconductor Corp), the two wire interface (TWI) is a bus communication

system that forms an important communications channel on the RCAT™. Onboard devices that are controlled by

the TWI include: 1M-bit Serial EEPROM ADXL345 Accelerometer chip

The TWI interface is also broken out for your use. Interface to a 3.3Vdc version as well as a 5Vdc version are provided.

Schem atic

Figure 13

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Notes

Connector J2 provides access to the TWI by you external devices. Pullups R4 and R5 are provided relieving you of the need to pull the lines to Vcc. Also note the 3.3Vdc to 5Vdc level shifters (Q1/Q2) enable the connection of

3.3Vdc TWI devices to J2 pins 5 and 7. The example software solution provided with your RCAT™ board configures the TWI for operation at 400KHz, so keep this in mind when connecting your device(s) and using the example solution provided.

1M-bit serial EEPROM

The RCAT™ board includes a 1M-bit Serial EEProm chip, the STMicro M24M01-RMN6TP, for use however you desire. This chip is managed via the TWI (described earlier). The schematic for this device is also shown above. Please consult the manufacturer’s datasheets (M24M01-R) for details on how to properly use this device.

The example software solution provided with your RCAT™ board includes examples of how to read and write from/to this device. Please note that since it hangs on the TWI, which is accessible from the outside world, you could turn off any control from the CPU and use your own external control mechanisms to read and write this chip.

Accelerometer

Onboard the RCAT™ is an ADXL345 accelerometer chip made by Analog Devices. Get datasheet here. The need for an accelerometer in robotics applications is so commonplace that we decided to relieve our users from the chore of buying and attaching a separate module dedicated to this purpose. This chip is a very powerful accelerometer that features 3-axis measurement of attitudinal and inertial situations that make it possible to do very accurate reckoning of position, tracking of motion and determination of pitch/roll/yaw in almost limitless ways. The axis orientation of the chip is noted on the silkscreen of the RCAT™ as shown here:

Figure 14

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

A-B

0x3A

0x3B

B-C

0xA6

0xA7

The example software solution provided with your RCAT™ includes code to read this device and calculate pitch

and roll information. Of course, much more complex data manipulation is possible (see the Analog Devices datasheet for details), but this example will provide you with the basic methods for reading and writing the various registers on the device.

Like the EEProm, the accelerometer is hung on the TWI system so that you could control it externally is desired.

Referring to the schematic under the TWI section above you see two jumpers associated with this device.

Jumper JP23 determines the address at which the accelerometer is configured:

Position Write addr Read addr

Table 3

The accelerometer features two interrupt outputs that are actuated in response to certain events inside the chip. These interrupt outputs are sent to the CPU on PE4 and PE5 as shown in the schematic in the TWI section above. In addition these interrupts are broken out to connector J5 on positions PE4 and PE5 for monitoring by your external hardware.

SPI Interface

CPU ports PB1, PB2 and PB3 are brought out to connector J1 as shown below:

Schem atic

As shown, access to the CPU /RST pin as well as Vcc and Gnd are also provided. J1 is laid-out to allow easy connection to programming devices that utilize Serial Peripheral Interface (SPI). If not utilizing the SPI system, these CPU ports are available for general purpose use.

Figure 15

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

ADC AREF

Most applications will do fine using the CPU’s internal Vref for analog to digital conversion. For those applications requiring an external reference, access to the AREF is provided as shown in the schematic below.

Schem atic

Please consult the ATMega™ datasheet for details on the proper implementation of this input.

Figure 16

JTAG

If y ou a r e u s i ng a n in-circuit - emul at or ( I CE) like the Atmel ATATMEL-ICE™, which we highly recommend, the JTAG interface connect o r J 4 (shown below) provides a si m pl e pl u g -i n poi nt f o r the ICE. If you are done wi t h o r a r e n ot ot h e r w ise using the connector for ICE or ot he r J TAG pur p os e s, then CPU ports PF4 -PF7 are available to y o u r a pp l ication. Note that Vcc, Gnd and C P U /RST are also accessible v i a J 4 .

Schem atic

Figure 17

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Mosfet Drivers

One feature missing on virtually every other robotic control board we know of is the ability to drive highercurrent devices from the board without the addition of extra add-on boards.

That’s where the onboard mosfet driver subsystem comes into play.

Schem atic

Two mosfet chips are provided. Each is a NX3008NBK,215 device from NXP Semiconductor. You can find the datasheet for the device here: http://www.mouser.com/ds/2/302/NX3008NBK-354913.pdf

Connectors JP26 and JP27 allow you to connect loads in a variety of ways. Here is one possible example using the mosfet as a simple switch:

Figure 18

Figure 19

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Note:

When using an external power source as shown above, it is required to make sure the power source return is common with the RCAT™ ground since the mosfets flow the load current to ground. This sets-up the possibility of flowing (relatively) large currents through the RCAT™ ground causing ground noise. Although the ground plane on the board will mitigate most of this, it is still best if you connect the return line of your external power source to a ground point on the RCAT™ that is as close to JP26 or JP27 as is possible.

The best options would be one of the ground access points on I/O connector J5 like the following:

This example shows the use of mosfet Q3 with the return line of the external power source tied to J5 pin 32-C which connects the return line to the RCAT™ ground at a point very close to the Q3 source pin (see the yellow arrows).

Figure 20

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Install shunt

Alternatives for con trolling the mosfets

Notice the schematic below that the CPU port PL0 directly controls Q3:

Figure 21

Now notice in the diagram below that PL0 also connects to jumper JP28 which then goes to J5. This opens the option of controlling the mosfet from the CPU or from an external source. Of course if you decide to utilize external control you will need to install a shunt on JP28. You should also make sure that port PL0 on the CPU is configured as a high-impedance input to avoid back-driving the external input and possibly damage one or both ends of the circuit.

One possible configuration of this arrangement might provide for PWM control of the mosfet by connecting one of the PWM outputs (for example J5 position 2 which is the PE3/OC3A PWM output from the CPU) to the PL0_A input of J5.

Figure 22

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

As you can see, the possibilities are very great and mostly just depend upon you needs.

Direct I/O Access

As noted previously, there are many CPU ports that are broken out directly to various points on the RCAT™

control board. The circled connectors in the image below show all the points where direct access is available:

Figure 23

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Primary I/O Connector

First we will discuss connector J5 which we call the Primary I/O connector.

On the schematic you may see:

This indicates that connector J5 is a 3-row connector with rows A, B, and C. These row designators map to the board as shown above. J5 has been laid-out this way to allow easy connection to devices that require signal, Vcc, and ground connections in a 3-pin format. Most robot servos, sonar distance devices and other such devices are designed this way.

To the right of the J5 are labels GND, Vcc, SIG which identify the purpose of each row. So – row ‘A’ connects to each relevant port on the CPU, while rows B and C are common connections to Vcc and GND respectively.

Above J5 are labels that show what port the SIG row of each position connects to.

Just under J5 are position labels which are meant for easy reference. For example, J5 Position21-A refers to the connection to CPU port PL1.

JTA G Con nector

Next in our discussion is connector J4 which serves as the JTAG connector as discussed in the JTAG section earlier. If the JTAG functions are not required, then several of the pins on J4 are available for direct port connection. Here is the schematic of that connector:

Figure 24

Figure 25

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

As illustrated, J4 gives you direct access to CPU ports PF4, PF5, PF6 and PF7. In addition you can access the board ground, the CPU reset pin (/RST) and board Vcc. Pins 7 and 8 on J4 are not connected to anything.

SPI Co nnector

Similar to J4, discussed above, connector J1 serves a dual purpose. It gathers all the signals together that are

required for use in the CPU’s SPI system. See the ATMega™ manual for details on this. Alternatively, J1 presents

several ports for direct access. Here is the schematic:

As shown, J1 gives you direct access to CPU ports PB1, PB2, and PB3 along with Vcc, /RST, and GND access.

Figure 26

USART 0

There are no direct connection paths between USART0 and any connector on the RCAT™. All access to USART0 is peformed through the USB, RS232 or RS422/485 interfaces.

USART 2 Port – J1 4 and J7

A complete discussion of the USART ports follows in the next sections. However, if you are not using the usarts, most of them have direct access to their associated CPU port pins. J14 are J7 are is two of those. This is, perhaps, the most challenging serial port on the board to understand, so we will show the annotated schematic to aid you:

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Figure 27

As shown above, J14 is a 3-row header with each row having all its pins tied together. This allows wire-or’ing of capable devices as described later in the USART 2 section. When not using this function, if you follow the bold red line you will see that J14 row A pins eventually find their way to CPU port PH0 which is also the USART 2 RXD line. In order to gain access to the port you must install shorting shunts on jumper JP9 across pins A-B and jumper JP11 across pins A-B.

In similar fashion, access to CPU port PH1 (USART 2 TXD) is provided on connector J7 pin 1. Following the bold green line on the above schematic you will see the signal path. To complete the path shorting shunts must be installed on jumper JP8 across pins A-B and on jumper JP10 across pins B-C.

IMPORTANT!!

In this configuration you must ensure that jumper JP20 is NOT installed or the output from the level shifter chip U9 will conflict with the CPU port.

3.3 Volt Input/ Output

As you can see in the schematic below, ports PH0 and PH1 can also be broken out as 3.3V I/O. By installing the shunt on JP8 across pins B-C, and JP10 across pins B-C (follow the bold violet lines) the signal at J7 pin 1 can be brought into the board as a 3.3Vdc level where it will be fed into U8 pin 20 and translated to a 5Vdc level for forwarding to the CPU. Likewise, following the bold blue lines on the schematic, by installing shunts on jumper JP11 across pins A-B and JP9 across pins B-C, the signals present on J14 row A are sent through a similar translation on U9.

In this configuration, a shunt must be installed across jumper JP22.

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Finally, refer to the schematic excerpts below:

Figure 28

Figure 29

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

74VLC4245A Octal dual supply translating transceiver (3-state)

Figure 30

While the 3.3Vdc to 5Vdc level translators ARE bidirectional, they ARE NOT TRANSPARENT…..the DIR inputs on

each translator must be set for the correct direction of signal flow. Referring to Figures 28, 29 and 30 above, with the shunts installed as instructed, we see (following the violet line) J7 pin 1 reaching IC U8 on pin 20 which is the B2 pin on the translator chip. The direction control of U8 is handled by signal XLAT1_DIR which connects to the CPU on port PH7. First, PH7 must be configured as an output through its associated Data Direction Register (DDR). Then, assuming the output of PH7 is high(1), this will configure translator U8 as an output from the CPU to J7 since a logic 1 at the DIR pin causes the translator to conduct from the A side to the B side. With PH7 low(0), then P7 pin 1 may be used as an input.

Of course, remember to set the CPU port DDR correctly. In the example just given, port PH1 DDR bit must be configured.

Also, notice that both translators are Enabled or disabled in tandem by the state of port PG5 which connects to the /OE pins of each translator.

For more information, consult the translator datasheets:

http://www.nxp.com/documents/data_sheet/74LVC4245A.pdf

USART 3 Port – J8

Connector J8 allows direct access to CPU ports PJ0 and PJ1 (via J8) if the USART 3 functions are not in use.

These connections can be routed through the 3.3Vdc to 5Vdc level translators in similar fashion to USART 2 as described earlier.

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Refer to Figure 31 below:

Schem atic

Direct access to CPU port PJ0 from J8 pin 2 is obtained by installing a shunt on jumper JP13 across pins A-B. See the green lines in the figure. Likewise, direct access to CPU port PJ1 from J8 pin 1 is obtained by installing a shunt on jumper JP12 across pins A-B. See the orange lines in the figure.

As in the previous section, both of these signals can be level-translated. See the operation of the level translators in the previous section for details.

REMEMBER!!!

Never install JP21 anytime that JP13 is NOT in installed the B-C position! Also, if U9 DIR is set to make the signal direction go from B to A (DIR = 0), then if JP21 is installed you must configure port PJ0 as an input (via its DDR)!

Figure 31

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

USART 1 Port – J6

Connector J6 allows direct access to CPU ports PD2 and PD3 (via J6) if the USART 1 functions are not in use.

These connections can be routed through the 3.3Vdc to 5Vdc level translators in similar fashion to USARTs 2 and 3 as described earlier.

Refer to Figure 32 below:

Schem atic

With shunts installed on JP6 across pins A-B and on JP15 across pins A-B, you gain direct connection from J6 pin 1 to CPU port PD3. Refer to the bold orange lines in Figure 32.

With shunts installed on JP7 across pins A-B and on JP17 across pins A-B, you gain direct connection from J6 pin 2 to CPU port PD2. Refer to the bold blue lines in Figure 32.

As with USARTS 2 and 3 described earlier, J6 can be routed through the 3.3Vdc to 5Vdc level translators in transit from J6 to/from the CPU chip.

Routing of J6 through the level translators is similar to the above USARTS, but there are a couple of twists to consider.

Figure 32

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Referring to Figure 33:

First, assuming all other things equal, the green signal path shows how you can route J6 pin 1 signal through translator U8 in similar fashion to the previous USARTS by installing shunts on jumper JP6 across pins B-C and on jumper JP15 across pins A-B.

Likewise the violet signal path shows how you can J6 pin 2 through translator U9 by installing shunts on jumper JP7 across pins B-C and on jumper JP17 across pins A-B.

Unlike the USARTS 2 and 3, the isolation jumper, JP20 is handled differently than jumpers JP21 and JP22 are in the other cases.

Also, please notice that U8 pin 7 connects directly to CPU port PD3. This is different from the other USARTS as well.

These differences are due to the fact that USART 1 is shared between J6 and J10. See the portion of Figure 33 showing J10 near the bottom? J10 is intended for direct connection to a Netburner™ Serial to Ethernet converter.

If J10 is not being used, then you will have no issues. If J10 IS being used, then you must make sure you do not also bring conflicting signals into J6.

By paying attention to the schematics you should be able to navigate this arrangement with no problems.

Figure 33

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

PORT

Access

Jumper(s)

PORT

Access

Jumper(s)

PB0

J5A/10

N/A

PF6

J4/3

N/A

PB1

J1/3

N/A

PF7

J4/9

N/A

PB2

J1/4

N/A

PH0

J7/2, J14A

JP9, JP11

PB3

J1/1

N/A

PH1

J7/1

JP8, JP10

PB4

J5A/11

N/A

PH2

J5A/7

N/A

PB5

J5A/12

N/A

PH3

J5A/8

N/A

PB6

J5A/13

N/A

PH4

J5A/9

N/A

PB7

J5A/14

N/A

PJ2

J5A/18

N/A

PD2

J6/2

JP7, JP17

PJ3

J5A/19

N/A

PD3

J6/1

JP6, JP15

PK0

J5A/26

N/A

PD5

J5A/15

N/A

PK1

J5A/27

N/A

PD6

J5A/16

N/A

PK2

J5A/28

N/A

PD7

J5A/17

N/A

PK3

J5A/29

N/A

PE2

J5A/1

N/A

PK4

J5A/30

N/A

PE3

J5A/2

N/A

PK5

J5A/31

N/A

PE4

J5A/3

N/A

PK6

J5A/32

N/A

PE5

J5A/4

N/A

PK7

J5A/33

N/A

PE6

J5A/5

N/A

PL0

J5A/20

JP28

PE7

J5A/6

N/A

PL1

J5A/21

JP29

PF0

J5A/34

N/A

PL2

J5A/22

N/A

PF1

J5A/35

N/A

PL3

J5A/23

N/A

PF2

J5A/36

N/A

PL4

J5A/24

N/A

PF3

J5A/37

N/A

PL5

J5A/25

N/A

PF4

J4/1

N/A

PF5

J4/5

N/A

One final note about USART 1…

In Figure 33 you can see how jumpers JP15 and JP17 can be installed across pins B-B thus connecting the signals to an RS232 transceiver. This is discussed in detail in upcoming sections, but be aware that no direct connection from this direction to USART 1 is possible.

Final comments about USA RT direct connectio ns

As can be seen direct connection to the CPU RXD/TXD ports at normal logic voltages (5V) is fairly simple.

However, when you decide to utilize the power of the level translators you must design your system carefully, making sure you do not cause signal conflicts to arise. This involves not only making sure you connect your hardware to the various connectors in the correct way, but it also involves making sure shunts are installed on the proper jumpers across the proper pins, and it also involves making sure all CPU ports involved are correctly configured as inputs, or outputs as needed, that the level translators being used are enabled or disabled as desired (/OE), and that the DIR pin on each translator is set or reset as appropriate. Although this takes a bit of planning, you will see that this layout provides you with a significant number of options for whatever hardware/software system you are trying to create.

Summary of direct access ports

The following table summarizes the 48 CPU ports that are directly accessible on the RCAT™:

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Table 4

USARTS, and Serial C ommunications Interfa ces

This section details the several different types of communications interfaces available on the RCAT™. The following is a list of all the different combinations you could have configured simultaneously.

USART 0:

USB RS232 RS422/485

USART 1: RS232

Ethernet (requires addition of Serial to Ethernet converter board such as Netburner™ SBL2E) Logic (5Vdc)

USART 2: Logic – Full Duplex (5Vdc)

Logic – Half Duplex (5Vdc)

USART 3:

Logic (5Vdc)

Given these possibilities, any of 24 different configurations can be created at any one time:

Note: All “logic” Interfaces are shown jumpered for 5Vdc operation

Configuration 1

USART Interface Access Jumper(s) and port configs USART0 USB J9 JP14(A-B), JP25(A-B), JP16(A-B), JP24(A-B) USART1 RS232 J12 JP15(B-C), JP17(B-C), JP20 Removed USART2 Logic/Full Duplex J7 JP10(B-C), JP11(B-C), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 2

USART Interface Access Jumper(s) and port configs USART0 RS232 J11 JP14(B-C), JP25(A-B), JP16(B-C), JP24(A-B) USART1 RS232 J12 JP15(B-C), JP17(B-C), JP20 Removed USART2 Logic/Full Duplex J7 JP10(B-C), JP11(B-C), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 3

USART Interface Access Jumper(s) and port configs USART0 RS422/485 J16 JP25(B-C), JP24(B-C) USART1 RS232 J12 JP15(B-C), JP17(B-C), JP20 Removed USART2 Logic/Full Duplex J7 JP10(B-C), JP11(B-C), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Configuration 4

USART Interface Access Jumper(s) and port configs USART0 USB J9 JP14(A-B), JP25(A-B), JP16(A-B), JP24(A-B) USART1 Logic J6 JP6(A-B), JP7(A-B), JP15(A-B), JP17(A-B) JP20 Removed USART2 Logic/Full Duplex J7 JP10(B-C), JP11(B-C), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 5

USART Interface Access Jumper(s) and port configs USART0 RS232 J11 JP14(B-C), JP25(A-B), JP16(B-C), JP24(A-B) USART1 Logic J6 JP6(A-B), JP7(A-B), JP15(A-B), JP17(A-B) JP20 Removed USART2 Logic/Full Duplex J7 JP10(B-C), JP11(B-C), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 6

USART Interface Access Jumper(s) and port configs USART0 RS422/485 J16 JP25(B-C), JP24(B-C) USART1 Logic J6 JP6(A-B), JP7(A-B), JP15(A-B), JP17(A-B) JP20 Removed USART2 Logic/Full Duplex J7 JP10(B-C), JP11(B-C), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 7

USART Interface Access Jumper(s) and port configs USART0 USB J9 JP14(A-B), JP25(A-B), JP16(A-B), JP24(A-B) USART1 Ethernet J10 JP6 Removed, JP7 Removed,

USART2 Logic/Full Duplex J7 JP10(B-C), JP11(B-C), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 8

USART Interface Access Jumper(s) and port configs USART0 RS232 J11 JP14(B-C), JP25(A-B), JP16(B-C), JP24(A-B) USART1 Ethernet J10 JP6 Removed, JP7 Removed,

USART2 Logic/Full Duplex J7 JP10(B-C), JP11(B-C), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

JP15 Removed, JP17 Removed,

JP20 Installed, PH7 = 0, PH6 = 1, PG5 = 0

JP15 Removed, JP17 Removed,

JP20 Installed, PH7 = 0, PH6 = 1, PG5 = 0

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Configuration 9

USART Interface Access Jumper(s) and port configs USART0 RS422/485 J16 JP25(B-C), JP24(B-C) USART1 Ethernet J10 JP6 Removed, JP7 Removed,

USART2 Logic/Full Duplex J7 JP10(B-C), JP11(B-C), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 10

USART Interface Access Jumper(s) and port configs USART0 USB J9 JP14(A-B), JP25(A-B), JP16(A-B), JP24(A-B) USART1 Ethernet J10 JP6 Removed, JP7 Removed,

USART2 Logic/Full Duplex J7 JP10(B-C), JP11(B-C), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 11

USART Interface Access Jumper(s) and port configs USART0 RS232 J11 JP14(B-C), JP25(A-B), JP16(B-C), JP24(A-B) USART1 Ethernet J10 JP6 Removed, JP7 Removed,

USART2 Logic/Full Duplex J7 JP10(B-C), JP11(B-C), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 12

USART Interface Access Jumper(s) and port configs USART0 RS422/485 J16 JP25(B-C), JP24(B-C) USART1 Ethernet J10 JP6 Removed, JP7 Removed,

USART2 Logic/Full Duplex J7 JP10(B-C), JP11(B-C), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 13

USART Interface Access Jumper(s) and port configs USART0 USB J9 JP14(A-B), JP25(A-B), JP16(A-B), JP24(A-B) USART1 RS232 J12 JP15(B-C), JP17(B-C), b USART2 Logic/Half Duplex J14 JP10(A-B), JP11(A-B), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

JP15 Removed, JP17 Removed,

JP20 Installed, PH7 = 0, PH6 = 1, PG5 = 0

JP15 Removed, JP17 Removed,

JP20 Installed, PH7 = 0, PH6 = 1, PG5 = 0

JP15 Removed, JP17 Removed,

JP20 Installed, PH7 = 0, PH6 = 1, PG5 = 0

JP15 Removed, JP17 Removed,

JP20 Installed, PH7 = 0, PH6 = 1, PG5 = 0

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Configuration 14

USART Interface Access Jumper(s) and port configs USART0 RS232 J11 JP14(B-C), JP25(A-B), JP16(B-C), JP24(A-B) USART1 RS232 J12 JP15(B-C), JP17(B-C), JP20 Removed USART2 Logic/Half Duplex J14 JP10(A-B), JP11(A-B), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 15

USART Interface Access Jumper(s) and port configs USART0 RS422/485 J16 JP25(B-C), JP24(B-C) USART1 RS232 J12 JP15(B-C), JP17(B-C), JP20 Removed USART2 Logic/Half Duplex J14 JP10(A-B), JP11(A-B), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 16

USART Interface Access Jumper(s) and port configs USART0 USB J9 JP14(A-B), JP25(A-B), JP16(A-B), JP24(A-B) USART1 Logic J6 JP6(A-B), JP7(A-B), JP15(A-B), JP17(A-B) JP20 Removed USART2 Logic/Half Duplex J14 JP10(A-B), JP11(A-B), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 17

USART Interface Access Jumper(s) and port configs USART0 RS232 J11 JP14(B-C), JP25(A-B), JP16(B-C), JP24(A-B) USART1 Logic J6 JP6(A-B), JP7(A-B), JP15(A-B), JP17(A-B) JP20 Removed USART2 Logic/Half Duplex J14 JP10(A-B), JP11(A-B), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 18

USART Interface Access Jumper(s) and port configs USART0 RS422/485 J16 JP25(B-C), JP24(B-C) USART1 Logic J6 JP6(A-B), JP7(A-B), JP15(A-B), JP17(A-B) JP20 Removed USART2 Logic/Half Duplex J14 JP10(A-B), JP11(A-B), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Configuration 19

USART Interface Access Jumper(s) and port configs USART0 USB J9 JP14(A-B), JP25(A-B), JP16(A-B), JP24(A-B) USART1 Ethernet J10 JP6 Removed, JP7 Removed,

USART2 Logic/Half Duplex J14 JP10(A-B), JP11(A-B), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 20

USART Interface Access Jumper(s) and port configs USART0 RS232 J11 JP14(B-C), JP25(A-B), JP16(B-C), JP24(A-B) USART1 Ethernet J10 JP6 Removed, JP7 Removed,

USART2 Logic/Half Duplex J14 JP10(A-B), JP11(A-B), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 21

USART Interface Access Jumper(s) and port configs USART0 RS422/485 J16 JP25(B-C), JP24(B-C) USART1 Ethernet J10 JP6 Removed, JP7 Removed,

USART2 Logic/Half Duplex J14 JP10(A-B), JP11(A-B), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 22

USART Interface Access Jumper(s) and port configs USART0 USB J9 JP14(A-B), JP25(A-B), JP16(A-B), JP24(A-B) USART1 Ethernet J10 JP6 Removed, JP7 Removed,

USART2 Logic/Half Duplex J14 JP10(A-B), JP11(A-B), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

Configuration 23

USART Interface Access Jumper(s) and port configs USART0 RS232 J11 JP14(B-C), JP25(A-B), JP16(B-C), JP24(A-B) USART1 Ethernet J10 JP6 Removed, JP7 Removed,

USART2 Logic/Half Duplex J14 JP10(A-B), JP11(A-B), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

JP15 Removed, JP17 Removed,

JP20 Installed, PH7 = 0, PH6 = 1, PG5 = 0

JP15 Removed, JP17 Removed,

JP20 Installed, PH7 = 0, PH6 = 1, PG5 = 0

JP15 Removed, JP17 Removed,

JP20 Installed, PH7 = 0, PH6 = 1, PG5 = 0

JP15 Removed, JP17 Removed,

JP20 Installed, PH7 = 0, PH6 = 1, PG5 = 0

JP15 Removed, JP17 Removed,

JP20 Installed, PH7 = 0, PH6 = 1, PG5 = 0

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Configuration 24

USART Interface Access Jumper(s) and port configs USART0 RS422/485 J16 JP25(B-C), JP24(B-C) USART1 Ethernet J10 JP6 Removed, JP7 Removed,

USART2 Logic/Half Duplex J14 JP10(A-B), JP11(A-B), JP8(A-B), JP9(A-B) JP22 Removed USART3 Logic J8 JP12(A-B), JP13(A-B), JP21 Removed

RS422/485 Interface

As shown in the configurations above, USART0 can be configured to use the RS422/485 interface. This interface is accessible at connector J16. The interface utilizes the Exar SP3071EEN-L (follow link for datasheet). The schematic is shown in Figure 34 below.

Schem atic

JP15 Removed, JP17 Removed,

JP20 Installed, PH7 = 0, PH6 = 1, PG5 = 0

Figure 34

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Free RS232 Channel

The RCAT™ has one channel of the ICL3243E RS232 Transceiver that is not committed to any USART or other

circuit on the board. It breaks out to connector J13 for use as you see fit. You can view the datasheet for the

ICL3243E here. The diagram is shown in Figure 35.

Schem atic

Ethernet System

We considered placing an Ethernet system on the RCAT™ board, along with a wireless transceiver like some products do. However, we felt as though this is a critical system that deserves to be done in a comprehensive-

enough manner that we couldn’t justify trying to stuff something “good enough” onto this board. Instead we

opted to provide you with the connectivity via the various ports and serial protocols so that you can attach whatever Ethernet or wireless hardware you so choose. This also relieves you of the burden of the requisite coding that goes along with having such a system onboard.

We have had tremendous success with the Netburner™ series of Serial to Ethernet products. So we opted to provide an interface to the Netburner™ SBL2E. You can view the product data here.

Figure 35

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Referring to Figure 36 below, a 16 conductor ribbon cable connects nicely between J16 and the Netburner™. A Network able can then be connected to the Netburner™ and you are fully Ethernet-enabled. The Netburner™ SBL2E costs around $37.00 depending on where you buy it and offers the cleanest most reliable Ethernet add-on we have found.

Figure 36

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Development Systems

Although many combinations of programming environments and hardware debugging and programming tools are available, our goal is to get you up and running on your system as fast and inexpensively as possible.

To that end, we present some recommendations:

Programming IDE (int eractive Developmen t Environment)

Name: Atmel Studio Manufacturer: Atmel Languages: C, C++ Platform: Windows Cost: Free – just must register an email address to download Access at: http://www.atmel.com/products/microcontrollers/avr/default.aspx

RCAT™ Startup Solut io n Software

Name: RCAT Manufacturer: Robot Circuits, LLC Language: C Platform: Windows, Atmel Studio 7x Cost: Included with board purchase

In-Circuit Emulator

Name: ATATMEL-ICE Manufacturer: Atmel Platform: Windows Cost: $92.94 (as of this publication date)

Purchase At: Mouser

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Demonstration Software

Another point of aggravation that you have probably encountered at some time or another if you have been doing this very long, is trying to gather up all the function libraries, configuring development environments, loading demonstration code, downloading datasheets for various devices, and more, only to find that the library(s) you thought you wanted were either out of date, or no longer available, or just plain broken, and the IDE configuration was cryptic and not documented well enough to let you easily load the demo software, and the demo software was SO basic that it was, for all intents and purposes, useless.

To that end we have provided a fully functional software solution that, once you have installed the Atmel Studio, and have copied the solution files to the proper locations on your computer, can be simply loaded and executed without all the usual drama.

We have provided the solution as a real-time operating system that uses a special AVR port of the open-source FreeRTOS library (see the FreeRTOS page here). Please note that the RCAT™ Startup solution uses files from the

published release of FreeRTOS that have been adapted to run with the RCAT™ board. These files have been annotated as such and renamed with an “RCAT_” prefix to identify them.

Yes – you SHOULD read the FreeRTOS documents and learn how to use the O/S. But the solution will load, compile and run even if you don’t at first.

The solution provided is more than just a “Demo”. It can actually serve as a root project for your applications. In it we

have written examples for:

 Operating the onboard LED  Configuring and reading the accelerometer chip (pitch and roll in degrees)  Accessing Extended RAM (the system comes configured to use Extended RAM as the heap and implements the

heap management routines of FreeRTOS, allowing dynamic memory management.

 Reading and writing the 1M-bit Serial EEPROM  Reading and writing the Ethernet com (assumes a Netburner™ is attached)  Operating the onboard mosfets  Configuring a simple PWM-based servo control  Configuring one ADC channel and reading a voltage on it  Performing timer-based read of a sonar distance measurement device similar to the Parallax PING™

These modules are all written as separate tasks in the FreeRTOS multitasking system that can be installed, removed, or reprioritized as you desire. Figuring out how to extend these tasks and how to extend the demonstrated techniques (for example to operate other USARTs) is a simple jump from this point.

As time progresses, we will extend this solution to provide modules for interfacing to other popular devices. We also welcome the addition of support for various modules on the github project.

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

RCAT™ Specifications

Primary Operating Voltage: 5Vdc

Standard Input Voltage: 5Vdc, (3A) Regulated

Optional Input Voltage: 7.5Vdc to 35Vdc with installation of LM7805C and appropriate heatsink Filter Cap is already installed on board

Onboard Voltages: 3.3Vdc (linear regulator – not heatsinked)

Current: 475mA (with no external devices driven)

Processor: Atmel ATMega™ 2560

Processor Speed: 16MHz (Crystal)

Board Length: 5.60 inches

Board Width: 3.50 inches

Max Height: 0.925 inches (without heatsinks)

I/O ports directly accessible: 48

Serial ports (USARTS): 4

Serial interfaces: RS232 (2), RS422/485 (1), USB 2.0 (CP2102-GM bridge)(1), Logic(3),

Uncommitted RS232(1)

CPU EEPROM: 4K bytes

CPU Static RAM: 8K bytes

CPU Extended RAM: 128K bytes (arranged as 2 pages of 64K bytes each)

CPU Program Flash RAM: 256K bytes

Other CPU Specifications: Per Atmel datasheets

Other Devices Onboard: ADXL345 Accelerometer Status LED (Green/Yellow)

RCAT-1A Rev A3 Designer’s manual Serious Power for the Serious Designer

Mechanical

In addition to the dimensional diagram (Figure 37), the RCAT™ board is available as a SketchUp model on the Robot Circuits Website. You can download the file here.

Figure 37

Schematic Diagram

A complete schematic diagram of the RCAT™ control board is available in pdf format at

RCAT Version 1A Rev A3 Schematic Page 1.pdf

RCAT Version 1A Rev A3 Schematic Page 2.pdf

RCAT RCAT-1A Revision A3 System Manual

Specifications and Main Features

Frequently Asked Questions

User Manual