Digilent Max32 Reference Manual
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Max32™ Board Reference Manual
Revised June 29, 2017
This manual applies to the Max32 rev. E
DOC#: 502-202
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 1 of 20
Overview
The Max32 is a microcontroller board based on the Microchip PIC32MX795F512L, a member of the 32-bit PIC32
microcontroller family. The Max32 is the same form factor as the Arduino™ Mega board and is compatible with
many Arduino shields as well as larger shields for use with the Mega boards. The Max32 is easy to use and suitable
for both beginners and advanced users experimenting with electronics and embedded control systems. It features
a USB serial port interface for connection to the IDE and can be powered via USB or an external power supply.
The Max32 can be programmed using the Multi-Platform Integrated Development Environment (MPIDE), an
environment based on the original Arduino IDE and modified to support PIC32. It contains everything needed to
start developing embedded applications. The Max32 has 83 I/O pins that support a number of peripheral
functions, such as UART, SPI, I2C ports, and pulse width modulated outputs. Sixteen of the I/O pins can be used as
analog inputs or as digital inputs and outputs.
The PIC32 microcontroller on the Max32 also provides a 10/100 Ethernet MAC, USB 2.0 full-speed OTG controller,
and two CAN controllers. An add-on board like the Network Shield™ is needed to use these advanced peripherals.
The Max32 can be powered via USB, an external AC-DC power adapter, or batteries.
The chipKIT Max32 board.
A Microchip® PIC32MX795F512L
microcontroller (80 MHz, 512K Flash, 128K
RAM)
3.3V operating voltage
90mA typical operating current
7V to 15V input voltage (recommended)
20V input voltage (maximum)
83 available I/O pins
16 analog inputs
0V to 3.3V analog input voltage range
+/-18mA DC current per pin
a 10/100 Ethernet MAC
a USB 2.0 full-speed OTG controller
2 CAN controllers
Features include:
Max32™ Board Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 2 of 20
1 Max32 Hardware Overview
The Max32 board has the following hardware features:
1. USB Connector for USB Serial Converter
This connects to a USB port on the PC to provide the communications port for the MPIDE to talk to
the Max32 board. This can also be used to power the Max32 board when connected to the PC.
2. J11: Microchip Debug Tool Connector
This connector is used to connect Microchip programmer/debugger tools, such as the PICkit™ 3, for
in-circuit serial programming (ICSP). This allows the Max32 board to be used as a traditional
microcontroller development board using the Microchip MPLAB® IDE.
3. J2: External Power Connector
This is used to power the Max32 board from an external power supply. This is a 5.5mm x 2.1mm
barrel connector. It is wired with the center terminal as the positive supply voltage. The power supply
voltage must be in the range of 7V to 15V.
4. Power Supply – 3.3V Regulator
Voltage regulator for the 3.3V power supply. This power supply can provide up to 500mA of current.
5. JP1: Power Select Jumper
This jumper is used to route power from the external power connector through the on-board 5V
voltage regulator or to bypass the 5V regulator. The REG position routes power through the 5V
regulator. The BYP position bypasses the on-board 5V regulator. With this jumper in the BYP position,
the maximum input voltage that can be applied at the external power connector is 6V.
6. Power Supply – 5V Regulator
Max32™ Board Reference Manual
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This on-board 5V voltage regulator regulates the input voltage applied at the external power
connector to 5V. This is used to power the 3.3V regulator and to provide 5V power to expansion
shields. This regulator can provide up to 800mA of current.
7. J2: Shield Power Connector
This connector provides power to I/O expansion shields connected to the board.
8. PIC32 Microcontroller
The PIC32MX795F512L microcontroller is the main processor for the board.
9. J5, J7: Analog Signal Connectors
These connectors provides access to analog/digital I/O pins on the microcontroller.
10. User LED
LED connected to digital signal pin 13.
11. J6, J8, J9, J15: Digital Signal and Power Connectors
These are shown as four connectors in the Max32 schematic. There is a single connector loaded
across all four when the board is assembled. These provide 5V power, ground, and access to digital
I/O pins on the microcontroller to shields connected to the board.
12. JP3 & JP4: SPI Master/Slave Select Jumpers
These jumpers are used to switch the SPI signals for use of the Max32 board as an SPI master device
or as an SPI slave device. Both jumpers should be switched together. Place the shorting blocks in the
MASTER position for master operation and in the SLAVE position for slave operation. Normally, these
jumpers are in the MASTER position.
13. J13: SPI Signal Connector
This connector provides alternative access to the SPI signals. This is used by some shields for access to
the SPI bus.
14. J3, J4, J14: Digital Signal Connectors
These connectors provides access to digital I/O pins on the microcontroller.
15. J18 - I2C
Dedicated I2C signals. These signals are connected directly to I2C1 on the microcontroller and are
shared with pins 20 and 21 on connector J4.
16. Communications Status LEDs
These LEDs indicate activity on the USB serial interface.
17. Reset Button
This button can be used to reset the microcontroller, restarting operation from the boot loader.
Max32™ Board Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 4 of 20
2 Max32 Jumper Settings
The development platforms use a Microchip PIC32 microcontroller. These are 32-bit products that bring
unprecedented features to the Arduino community. In order to maintain compatibility with existing hardware and
software, additional jumpers and row headers are provided. This document describes the functionality of the
jumpers listed in Fig. 2 below.
Figure 2. Max32 Jumpers.
Max32™ Board Reference Manual
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Other product and company names mentioned may be trademarks of their respective owners.
Page 5 of 20
Jumper
Function
JP1
POWER SELECT: Used to connect/bypass the on-board 5V regulator when using a power
supply connected to J2.
J4 supply is regulated (i.e., 5V will be present
on 5V pin).
J4 supply bypasses regulator (i.e., Supply
voltage will be present on 5V pin)
Note: To protect the PIC32 MCU, a 3.3V on-board regulator will always be enabled
regardless of JP2 settings.
Note: If you’re not sure what POWER SELECT does, be safe and keep JP1 on the two right-
most pins so the J2 supply is regulated.
JP3/JP4
SPI SELECT: Used to configure the Max32 as either a Master or Slave when using the SPI.
The board can be connected to another device or even another microcontroller through
the SPI connector (J13).
configured as an SPI Master
configured as an SPI Slave
3 Max32 Hardware Description
3.1 MPIDE and USB Serial Communication
The Max32 board is designed to be used with the Multi-Platform IDE (MPIDE). MPIDE is a modified version of the
Arduino IDE that supports the PIC32 microprocessors and is fully backwards-compatible with the Arduino IDE. The
MPIDE uses a serial communications port to communicate with a boot loader running on the Max32 board. The
serial port on the Max32 board is implemented using an FTDI FT232R USB serial converter. Before attempting to
use the MPIDE to communicate with the Max32, the appropriate USB device driver must be installed.
The Max32 board uses a standard mini-USB connector for connection to a USB port on the PC. When the MPIDE
needs to communicate with the Max32 board, the board is reset and starts running the boot loader. The MPIDE
then establishes communications with the boot loader and downloads the program to the board.
Max32™ Board Reference Manual
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Page 6 of 20
When the MPIDE opens the serial communications connection on the PC, the DTR pin on the FT232R chip is driven
low. This pin is coupled through a capacitor to the MCLR pin on the PIC32 microcontroller. Driving the MCLR line
low resets the microcontroller, restarting execution with the boot loader.
This automatic reset action (when the serial communications connection is opened) can be disabled. To disable
this operation, there is a cuttable trace on the bottom of the board between the pins on JP5. JP5 is normally not
loaded. If the trace between the pins on JP5 has been cut, the automatic reset operation can be restored by
loading JP5 and inserting a shorting block across it.
Two red LEDs (LD1 and LD2) will blink when data is being sent or received between the Max32 and the PC over the
serial connection.
The header connector J12 provides access to the other serial handshaking signals provided by the FT232R.
Connector J12 is not loaded at the factory and can be loaded by the user to access these signals.
3.2 Power Supply
The Max32 is designed to be powered either via USB or from an external power supply. There is an automatic
switchover circuit that causes the external supply to be used if both supplies are present.
The power supply section in the Max32 uses two voltage regulators. The first regulates the external voltage to 5V
to power the VCC5V0 bus. The second regulates the VCC5V0 bus to 3.3V to provide power to the VCC3V3 bus that
powers the PIC32 microcontroller.
The 5V voltage regulator is normally an NCP1117. The board is designed to be able to also use an LM1117, but the
NCP1117 is the part normally used. The NCP1117 is rated for an output current of 1A (the LM1117 is rated for
800mA). The dropout voltage of the NCP1117 is a maximum of 1.2V at the rated output current (1.3V for the
LM1117).
There is a reverse-polarity protection diode in the external power supply circuit. Considering the diode drop plus
the forward drop across the regulator, the minimum input voltage to the regulator should be 7V to produce a
reliable 5V output. The absolute maximum input voltage of both the NCP1117 and the LM1117 is 20V. The
recommended maximum operating voltage is 15V.
For input voltages above 9V, the regulator will get extremely hot when drawing high currents. Both the NCP1117
and the LM1117 have output short circuit protection and internal thermal protection and will shut down
automatically to prevent damage.
The 3.3V regulator is a Microchip MCP1725. This regulator is rated for a maximum output current of 500mA. The
absolute maximum input voltage for the MCP1725 is 6V. This regulator has internal short circuit protection and
thermal protection. It will get noticeably warm when the current consumed by the VCC3V3 bus is close to the
500mA maximum.
The 5V power bus VCC5V0 can be powered from one of three sources:
The USB5V0 bus when the board is operating under USB power
The output of the on-board 5V regulator when operating from an external 7V – 15V supply
Directly from the external supply when operating from a regulated 5V external supply with jumper JP1 in the
BYP position.
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