Microchip Technology PICtail User Manual
2004 Microchip Technology Inc. DS51523A
Mixed Signal
PICtail™ Demo Board
User’s Guide
DS51523A-page ii 2004 Microchip Technology Inc.
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• Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
• There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
• Microchip is willing to work with the customer who is concerned about the integrity of their code.
• Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
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Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
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Microchip received ISO/TS-16949:2002 quality system certification for
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October 2003. The Company’s quality system processes and
procedures are for its PICmicro
®
8-bit MCUs, KEELOQ
®
code hopping
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and manufacture of development systems is ISO 9001:2000 certified.
Mixed Signal PICtail™ Demo
Board User’s Guide
2004 Microchip Technology Inc. DS51523A-page iii
Table of Contents
Preface ........................................................................................................................... 1
Chapter 1. Product Overview ........................................................................................ 5
1.1 Introduction ..................................................................................................... 5
1.2 Purpose and Utility of the Mixed Signal PICtail™ Demo Board ..................... 5
1.3 Contents of the Mixed Signal PICtail™ Demo Board Kit ................................ 5
Chapter 2. Installation and Operation .......................................................................... 7
2.1 Introduction ..................................................................................................... 7
2.2 Features ......................................................................................................... 7
2.3 Getting Started ............................................................................................... 7
2.4 Running the demos ...................................................................................... 13
Appendix A. Schematics and Layouts ...................................................................... 17
A.1 Introduction .................................................................................................. 17
Appendix B. Bill-Of-Materials (BOM) ......................................................................... 25
Appendix C. MixedSignal_V100.asm Description .................................................... 27
Appendix D. DAC_dtmf.asm Source Code ............................................................... 29
Appendix E. MixedSignal_16f767i.lkr Source Code ................................................. 39
Appendix F. DTMF Scope Captures .......................................................................... 41
Appendix G. Scope Probe Noise Captures ............................................................... 43
Appendix H. Sine Wave and Filtered DTMF Scope Captures ................................. 45
Appendix I. MPLAB® IDE Screen Capture ................................................................ 47
Worldwide Sales and Service .................................................................................... 48
Mixed Signal PICtail™ Demo Board User’s Guide
DS51523A-page iv 2004 Microchip Technology Inc.
NOTES:
Mixed Signal PICtail™ Demo
Board User’s Guide
2004 Microchip Technology Inc. DS51523A-page 1
Preface
INTRODUCTION
This chapter contains general information that will be useful to know before using the
Mixed Signal PICtail™ Demo Board. Items discussed in this chapter include:
• About This Guide
• Conventions Used in this Guide
• Recommended Reading
• The Microchip Web Site
• Customer Support
NOTICE TO CUSTOMERS
All documentation becomes dated, and this manual is no exception. Microchip tools
and documentation are constantly evolving to meet customer needs, so some actual
dialogs and/or tool descriptions may differ from those in this document. Please refer
to our web site (www.microchip.com) to obtain the latest documentation available.
Documents are identified with a “DS” number. This number is located on the bottom
of each page, in front of the page number. The numbering convention for the DS
number is “DSXXXXXA”, where “XXXXX” is the document number and “A” is the
revision level of the document.
For the most up-to-date information on development tools, see the MPLAB
®
IDE
on-line help. Select the Help menu, and then Topics to open a list of available on-line
help files.
Mixed Signal PICtail™ Demo Board User’s Guide
DS51523A-page 2 2004 Microchip Technology Inc.
ABOUT THIS GUIDE
Document Layout
This document describes how to use the Mixed Signal PICtail™ Demo Board. The
manual layout is as follows:
• Chapter 1. Product Overview – Important information about the Mixed Signal
PICtail™ Demo Board.
• Chapter 2. Installation and Operation – Includes instructions on how to get
started with this demo board and a detailed description of each function of the
demo board.
• Appendix A. Schematics and Layouts – Shows the schematic and layout
diagrams for the Mixed Signal PICtail™ Demo Board.
• Appendix B. Bill-Of-Materials (BOM) – Lists the parts used to build the Mixed
Signal PICtail™ Demo Board.
• Appendix C. MixedSignal_V100.asm Description – Example “Main” assembly
firmware for the PIC16F767-I/SS microcontroller used to demonstrate the various
features of the supported analog products.
• Appendix D. DAC_dtmf.asm Source Code – Example assembly source
firmware used to generate Dual Tone Multiple Frequency (DTMF) signals. This
firmware is utilized by the “Main” firmware, MixedSignal_v100.ASM.
• Appendix E. MixedSignal_16f767i.lkr Source Code – Linker script file used to
build the example PIC16F767 firmware.
• Appendix F. DTMF Scope Captures – Oscilloscope screen captures of the
various DTMF tones displaying their FFT to illustrate the quality of the DTMF
tones.
• Appendix G. Scope Probe Noise Captures – Isolating scope probe noise is
challenging. These scope captures illustrate the difference between using a
standard scope probe and using coaxial cable directly from the board into the
scope.
• Appendix H. Sine Wave and Filtered DTMF Scope Captures – Oscilloscope
screen capture of the 32-step sine wave routine and the DTMF waveform. The
DTMF waveform illustrates the non-filtered DAC output and a simple RC-filtered
output.
• Appendix I. MPLAB® IDE Screen Capture – MPLAB IDE 6.3x was used to gen-
erate the example source firmware. This screen capture illustrates the tool, the
project files and the included Watch windows.
Preface
2004 Microchip Technology Inc. DS51523A-page 3
CONVENTIONS USED IN THIS GUIDE
This manual uses the following documentation conventions:
DOCUMENTATION CONVENTIONS
Description Represents Examples
Arial font:
Italic characters Referenced books MPLAB® IDE User’s Guide
Emphasized text ...is the only compiler...
Initial caps A window the Output window
A dialog the Settings dialog
A menu selection select Enable Programmer
Quotes A field name in a window or
dialog
“Save project before build”
Underlined, italic text with
right angle bracket
A menu path File>Save
Bold characters A dialog button Click OK
A tab Click the Power tab
‘bnnnn A binary number where n is a
digit
‘b00100, ‘b10
Text in angle brackets < > A key on the keyboard Press <Enter>, <F1>
Courier font:
Plain Courier Sample source code #define START
Filenames autoexec.bat
File paths c:\mcc18\h
Keywords _asm, _endasm, static
Command-line options -Opa+, -Opa-
Bit values 0, 1
Italic Courier A variable argument file.o, where file can be
any valid filename
0xnnnn A hexadecimal number where
n is a hexadecimal digit
0xFFFF, 0x007A
Square brackets [ ] Optional arguments mcc18 [options] file
[options]
Curly brackets and pipe
character: { | }
Choice of mutually exclusive
arguments; an OR selection
errorlevel {0|1}
Ellipses... Replaces repeated text var_name [,
var_name...]
Represents code supplied by
user
void main (void)
{ ...
}
Mixed Signal PICtail™ Demo Board User’s Guide
DS51523A-page 4 2004 Microchip Technology Inc.
RECOMMENDED READING
This user's guide describes how to use the Mixed Signal PICtail™ Demo Board. Other
useful documents are listed below. The following Microchip documents are available
and recommended as supplemental reference resources.
MCP4921/22, “12-Bit DAC with SPI™ Interface” Data Sheet (DS21897)
Provides detailed information regarding the MCP492X devices.
TC1320, “8-Bit Digital-to-Analog Converter with Two-Wire Interface” Data Sheet
(DS21386)
Provides detailed information regarding the TC1320 device.
TC1321, “10-Bit Digital-to-Analog Converter with Two-Wire Interface” Data Sheet
(DS21387)
Provides detailed information regarding the TC1321 device.
MCP3302/3304, “13-Bit Plus Sign Differential Input 2.7V Low-Power A/D
Converter with SPI™ Serial Interface” Data Sheet (DS21697)
Provides detailed information regarding the MCP3302 and MCP3304 devices.
MCP3204/3208, “2.7V 12-Bit A/D Converters with SPI™ Serial Interface” Data
Sheet (DS21298)
Provides detailed information regarding the MCP3204 and MCP3208 devices.
MCP1525/1541, “2.5V and 4.096V Voltage Reference” Data Sheet (DS21653)
Provides detailed information regarding the MCP1525 and MCP1541 devices.
TC55, “1 µA Low-Dropout Positive Voltage Regulator” Data Sheet (DS21653)
Provides detailed information regarding the TC55 device.
MCP1700, “Low-Quiescent Current LDO” Data Sheet (DS21826)
Provides detailed information regarding the MCP1700 device.
MCP616/617/618/619, “2.3V to 5.5V Micropower Bi-CMOS Op Amps” Data Sheet
(DS21613)
Provides detailed information regarding the MCP616, MCP617, MCP618 and MCP619
devices.
PIC16F737, PIC16F747, PIC16F767, PIC16F777, “PIC16F7X7 Data Sheet”
(DS30498)
Provides detailed information regarding the PIC16F737, PIC16F747, PIC16F767 and
PIC16F777 devices.
Preface
2004 Microchip Technology Inc. DS51523A-page 5
THE MICROCHIP WEB SITE
Microchip provides online support via our web site at www.microchip.com. This web
site is used as a means to make files and information easily available to customers.
Accessible by using your favorite Internet browser, the web site contains the following
information:
• Product Support – Data sheets and errata, application notes and sample
programs, design resources, user’s guides and hardware support documents,
latest software releases and archived software
• General Technical Support – Frequently Asked Questions (FAQ), technical
support requests, online discussion groups and Microchip consultant program
member listing
• Business of Microchip – Product selector and ordering guides, latest Microchip
press releases, listing of seminars and events, listings of Microchip sales offices,
distributors and factory representatives
CUSTOMER SUPPORT
Users of Microchip products can receive assistance through several channels:
• Distributor or Representative
• Local Sales Office
• Field Application Engineer (FAE)
• Technical Support
• Development Systems Information Line
Customers should contact their distributor, representative or field application engineer
(FAE) for support. Local sales offices are also available to help customers. A listing of
sales offices and locations is included in the back of this document.
Technical support is available through the web site at: http://support.microchip.com
In addition, there is a Development Systems Information Line which lists the latest
versions of Microchip's development systems software products. This line also
provides information on how customers can receive currently available upgrade kits.
The Development Systems Information Line numbers are:
1-800-755-2345 – United States and most of Canada
1-480-792-7302 – Other International Locations
Mixed Signal PICtail™ Demo Board User’s Guide
DS51523A-page 6 2004 Microchip Technology Inc.
NOTES:
Mixed Signal PICtail™ Demo
Board User’s Guide
2004 Microchip Technology Inc. DS51523A-page 7
Chapter 1. Product Overview
1.1 INTRODUCTION
This chapter provides an overview of the Mixed Signal PICtail™ Demo Board and
covers the following topics:.
• Purpose and utility of the Mixed Signal PICtail™ Demo Board
• Contents of the Mixed Signal PICtail™ Demo Board Kit
1.2 PURPOSE AND UTILITY OF THE MIXED SIGNAL PICtail™ DEMO BOARD
The Mixed Signal PICtail™ Demo Board allows the system designer to quickly evaluate
the suitability of several Microchip analog products for their product’s design.
Microchip’s Digital-to-Analog Converters (DACs), Analog-to-Digital Converters
(ADCs), V
REF
s, Low Dropout Output (LDO) regulators and the PIC16F7X7 devices are
supported. Evaluating precision analog products for specific applications can be
challenging for practical reasons. First, many products are only available in
surface-mount packages. Secondly, analog circuits tend to be affected adversely by
system noise. Common breadboarding techniques are not practical for these reasons.
The Mixed Signal PICtail™ Demo Board utilizes a 4-layer Printed Circuit Board (PCB),
with attention paid to reducing system noise.
The Mixed Signal PICtail™ Demo Board can isolate a specific device’s performance to
establish baseline performance. The board can be customized quickly for specific
system requirements.
1.3 CONTENTS OF THE MIXED SIGNAL PICtail DEMO BOARD KIT
This Mixed Signal PICtail™ Demo Board includes:
• The Mixed Signal PICtail™ Demo Board PCB
• PIC16F767 firmware that demonstrates how to configure and write to the
MCP492X, MCP482X and TC132X DAC products
• PIC16F767 firmware demonstrating DTMF generation using a DAC
• PIC16F767 firmware demonstrating sine-wave generation using a DAC
• PIC16F767 firmware to configure and read the MCP330X/320X SAR ADCs
• PIC16F767 firmware that configures and reads the MCP3551 Sigma-Delta ADC
• MCP617 dual op amp (standard 8-pin dual layout) that can be configured as an
input signal filter (ADC) or an output signal conditioning stage for the DACs
• Four DIP switches allow simple firmware mode selection
• Two indicator LEDs (red and green) for visual feedback
• PICkit™ 1 Flash Starter Kit’s 14-pin header provides an interface to Microchip’s
8- and 14-pin PICmicro
®
microcontroller devices
Mixed Signal PICtail™ Demo Board User’s Guide
DS51523A-page 8 2004 Microchip Technology Inc.
NOTES:
Mixed Signal PICtail™ Demo
Board User’s Guide
2004 Microchip Technology Inc. DS51523A-page 9
Chapter 2. Installation and Operation
2.1 INTRODUCTION
The Mixed Signal PICtail™ Demo Board demonstrates several Microchip analog
products in a signal chain configuration. The product families demonstrated include
DACs, ADCs, V
REF
s, LDOs and PICmicro® microcontroller devices. Evaluating
precision analog products for specific applications can be challenging due to noise
sources related to the PCB layout and not the silicon under evaluation. The Mixed Signal
PICtail™ Demo Board provides the necessary hardware and firmware to exercise each
of these devices in real-world applications. Users can quickly modify the existing
hardware and firmware to validate functionality for their specific system needs.
2.2 FEATURES
The Mixed Signal PICtail™ Demo Board has the following features:
• Printed Circuit Board (PCB) is a 4-layer board designed to minimize external
noise
• A 28-pin PICmicro (PIC16F767) microcontroller footprint is provided to permit
code development. In-Circuit Debugger is supported via the RJ11 connector
• The 14-pin header is designed to seamlessly interface to the PICkit™ 1 Flash
Starter Kit
• Firmware demonstrating DTMF generation on the MCP492X/482X DAC is
included
• Firmware demonstrating a precision sine-wave generation on the TC132X DAC is
included
• Firmware to configure and read the MCP330X/320X SAR ADCs is included
• Two precision voltage references (V
REF
s) are supported (can compare noise)
• Flexible amplifier circuit layout supports a dual op amp in multiple configurations
for either an input signal filter (ADC) or an output signal-conditioning stage for the
DACs
• Four DIP switches allow simple firmware mode selection are supported
• Two indicator LEDs (red and green) are supported
• Can be powered by either the PICkit™ 1 Flash Starter Kit or by an external 9V
supply
2.3 GETTING STARTED
The Mixed Signal PICtail™ Demo Board is assembled and tested for evaluation and
demonstration of the MCP492X, MCP482X, TC132X, MCP3551, MCP3302,
MCP3204, MCP1541, MCP1701, PIC16F767 and MCP617 features. Additional
product samples with footprints supported by this board are included. A block diagram
of the demo board is shown in Figure 2-1. Refer to Appendix A. “Schematics and
Layouts” and Appendix B. “Bill-Of-Materials (BOM)” for more detailed circuit
information.
Mixed Signal PICtail™ Demo Board User’s Guide
DS51523A-page 10 2004 Microchip Technology Inc.
FIGURE 2-1: Mixed Signal PICtail™ Demo Board Block Diagram.
S
1
Mode Switch
14
5
MCP1541
MCP1525
U9
V
REF
REF198G
U11
V
REF
(for debugging
MPLAB
®
ICD
J4
and programming)
PICkit™ 1
J1, J2, J3
Flash Starter Kit
TC55 (10V
V
IN
)
MCP1701 (10V
V
IN
)
MCP1700 (<6V
V
IN
)
V
DD2
V
IN
3
3
2
SPI™
CS0
SPI™
I
2
C™
CS1
3
SPI™
I2C™
V
OUTA
V
OUTB
V
OUTC
MCP4921 DAC
MCP4821 DAC
MCP4822 DAC
U5 & U10
MCP4922 DAC
TC1320 DAC
TC1321 DAC
U7
MCP3302/2304
ADC
U2
MCP617
Dual Op Amp
U12
MCP3551 ADC
U6/U8
U1
PICmicro
®
MCU
U4
Header
PIC16F767
Header
Installation and Operation
2004 Microchip Technology Inc. DS51523A-page 11
2.3.1 The Hardware
Figure 2-2 shows the layout of the Mixed Signal PICtail™ Demo Board with indicators
to points of interest, while Table 2-1 details the PICkit™ 1 Flash Starter Kit Header
connections. Jumpers JP1-JP5 are fully described in Section 2.3.2 “The Embedded
System Firmware”.
FIGURE 2-2: Mixed Signal PICtail™ Demo Board.
MCP3551-I/MS
22-Bit ADC
MCP1541 4.1V
MCP1525 2.5V
Voltage Reference
Analog Devices REF198G
4.096V Voltage Reference
MCP3551-I/P
22-Bit ADC
MCP4821-I/SN
MCP4822-I/SN
MCP4921-I/SN
12-Bit SPI™ DAC
JP3 V
OUTB
Selector
JP5 – MCP4X9X Part Selector
MCP4922-I/SL
12-Bit SPI™ DAC
TC132X-I/MS
8-Bit/10-Bit I
2
C™ DAC
TC55RP5002 5.0V LDO (10V V
IN
)
MCP1701T-5002I/CB 5.0V LDO (10V V
IN
)
MCP1700T-5002I/CB 5.0V LDO (6V V
IN
)
Mode Selector DIP switches
Red and Green LEDs
PIC16F767-I/SS
28-pin Flash
PICmicro
®
Microcontroller
with Internal Oscillator
JP1 V
OUTC
Selector
JP2 V
OUTA
Selector
MCP3302-I/SL
MCP3204-I/SL
13-Bit Differential SPI™ ADC
12-Bit Single-ended SPI™ ADC
MCP617-I/SN Dual Op Amp
(can be any dual or single op amp
using the standard footprint)
V
OUTD
SMA Connector
JP4a ADC V
REF
Source Selector
JP4b DAC V
REF
Source Selector
Mixed Signal PICtail™ Demo Board User’s Guide
DS51523A-page 12 2004 Microchip Technology Inc.
TABLE 2-1: PICkit™ 1 FLASH STARTER KIT 14-PIN HEADER INTERFACE
PINS
Pin Name
Pin
Number
Pin
Type
Buffer
Type
Description
V
SS
14 — — Electrical Ground. Both analog and digital.
V
IN
13 — — Power Supply Input. Refer to Note 2 in Appendix A
“Schematics and Layouts”. Do not plug in 9V
supply and connect to PICkit™ 1 Flash Starter Kit.
CS0 12 O — SPI™ Chip Select signal for the external ADCs. Do
not populate both the MCP3551 and the MCP3302
as they share the same CS0 signal.
SCK/SCL 11 O ST SPI Clock or I
2
C™ Clock Signal. Note that external
weak pull-up R
20
connects this signal to V
DD2
.
SDI/SDA 10 I/O ST SPI Data In or I
2
C Data signal (Data Out on ADC).
Note that external weak pull-up R14 connects this signal to V
DD2
.
SDO 9 O — SPI Data Out Signal (Data In on DAC and ADC)
CS1 8 O — SPI Chip Select Signal for the External DACs. Do not
populate both the MCP492X and the MCP482X as
they share the same CS0 signal.
LDAC 7 O — Latches the DAC Output When Low. Note the weak
pull-down resistor R
5
if the firmware doesn’t drive the
pin to a desired state.
V
REF_ADC
6 I — JP4 selects the V
REF
source to use as the ADC
reference signal. The PICmicro® microcontroller on
the PICkit™ 1 Flash Starter Kit may use this for its
internal ADC’s V
REF
.
LED0/TX 5 O — Active High Red LED Signal. This I/O also has the
USART’s TX signal multiplexed on it.
LED1/RX 4 I/O — Active High Green LED Signal. This I/O also has the
USART’s RX signal multiplexed on it.
SW0 3 I — S1’s Switch 1. This pin uses the internal pull-up resis-
tor to determine when the switch is open.
SW1 2 I — S1’s Switch 2. This pin uses the internal pull-up resis-
tor to determine when the switch is open.
SW2 1 I — S1’s Switch 3. This pin uses the internal pull-up resis-
tor to determine when the switch is open.
Legend: TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels
I = Input O = Output
Installation and Operation
2004 Microchip Technology Inc. DS51523A-page 13
2.3.2 The Embedded System Firmware
The Mixed Signal PICtail™ Demo Board firmware utilizes PICmicro® microcontroller
assembly language, Microchip MPASM™ assembler and MPLINK™ linker to build
the.HEX machine file. MixedSignal_v100.asm, DAC_dtmf.asm, p16F767.inc
and MCP492X_16f767i.lkr files are needed in your project to build the
MixedSignalPICtail.hex.
MixedSignal_v100.asm contains the main program and most of the subroutines.
After initialization of critical PICmicro microcontroller peripherals (including the internal
oscillator to 8 Mhz), the main loop polls the four DIP switches to determine the selected
mode of operation. The DIP switches create a 4-bit binary number from 0 to 15. If a
change of mode is detected for 100 ms during 500 ms of scanning, a new mode is
selected and the LEDs are alternately flashed for two seconds. Most of the modes will
time-out and re-scan the DIP switches periodically.
Refer to Appendix C. “MixedSignal_V100.asm Description” for the commented
source code further describing each mode.
Modes 0XXX primarily utilize the MCP492X DAC modes:
1. Mode0000: Use the DTMF generation subroutine (located in DAC_dtmf.asm)
to dial a phone number stored in memory. Analyze output on V
OUTB
or V
OUTD
’s
SMA connector. See Appendix F. “DTMF Scope Captures” for resulting
waveform frequency analysis.
2. Mode0001: Send 000h and FFFh commands to generate a 100 Hz R-R output
on the MCP492X. Probe V
OUTA
and V
OUTB
to see the resulting waveforms.
3. Mode0010: Send 400h and BFFh commands to generate a 100 Hz output on the
MCP492X. Probe V
OUTA
and V
OUTB
to see the resulting waveforms.
4. Mode0011: DACA = SHDN, DACB = SHDN, PIC = SLEEP. This mode demon-
strates the low-power nature of the DAC, the PICmicro microcontroller, the op
amp and the LDO. A power cycle is required after the mode switch is changed to
exit this mode.
5. Mode0100: DACB and DACA = 800h and Read w/PIC16F767 10b ADC, “broad-
cast on USART”. This mode is useful for evaluating the PICmicro microcontroller’s
ADC. A
IN_B
can be injected with an alternative signal and the result can be
analyzed through the 19200 baud async, 9-bit transmission. Microchip’s Data
View analysis tool, along with the MCP3551 USB evaluation board, provide a
“canned” analysis solution.
6. Mode0101: DACB = 801h, DACA = 800h and Read w/MCP3302 13b Dif, “broad-
cast on USART”. This mode is useful for evaluating the MCP3302 or the
MCP3204 ADC. A
IN_B
can be injected with an alternative signal and the result
can be analyzed through the 19200 baud async, 9-bit transmission. Microchip’s
Data View analysis tool, along with the MCP3551 USB evaluation board, provide
a “canned” analysis solution.
7. Mode0110: DACB and DACA = 800h and Read w/MCP3551, “broadcast on
USART”. This mode is useful for evaluating the MCP3551 ADC or the MCP1541
V
REF
. A
IN_B
can be injected with an alternative signal and the result can be
analyzed through the 19200 baud async, 9-bit transmission. Microchip’s Data
View analysis tool, along with the MCP3551 USB evaluation board, provide a
“canned” analysis solution.
8. Mode0111: Open for user to define their own routine.
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