Digilent Max32 Podręcznik referencyjny - Strona 8

Przeglądaj online lub pobierz pdf Podręcznik referencyjny dla Mikrokontrolery Digilent Max32. Digilent Max32 20 stron. Board

Max32™ Board Reference Manual

The fact that all I/O pins are 5V tolerant means that it is safe to apply 5V logic levels to any pins on the board

without risk of damaging the PIC32 microcontroller.

The minimum output high voltage of the PIC32 microcontroller is rated at 2.4V when sourcing 12mA of current.

When driving a high impedance input (typical of CMOS logic) the output high voltage will be close to 3.3V. Some 5V

devices will recognize this voltage as a logic high input, and some won't. Many 5V logic devices will work reliably

with 3.3V inputs.

3. 4 Input/Output Connections

The Max32 board provides 83 of the I/O pins from the PIC32 microcontroller to pins on the input/output

connectors J3, J4, J5, J7, J8, J9, and J14.

The PIC32 microcontroller can source or sink a maximum of 18mA on all digital I/O pins. However, to keep the

output voltage within the specified voltage range (V

0.4V, V

2.4V), the pin current must be restricted to +7/-

12mA. The maximum current that can be sourced or sunk across all I/O pins simultaneously is +/-200mA. The

maximum voltage that can be applied to any I/O pin is 5.5V. For more detailed specifications, refer to the

PIC32MX5XX/6XX/7XX data sheet available from www.microchip.com.

Connectors J3, J8, J9, and J14 are 2x8 female pin header connectors that provide digital I/O signals. Connector J4 is

a 1x8 female pin header that provides digital I/O signals. Connectors J5 and J7 are 1x8 female pin headers that

provide analog inputs as well as digital I/O signals.

Connectors J6 and J15 are two-pin headers that provide power and ground to shield boards. J6 provides two pins

connected to the VCC5V0 bus and J15 provides two pins connected to GND.

Note that although J6, J8, J9, and J15 are shown as separate connectors on the schematic, a single connector part

is loaded across all of them when the board is manufactured.

On connectors J3 and J14, the outer row (closer to the board edge) of pins corresponds to the I/O connector pins

on an Arduino Mega or Mega 2560 board. The inner row of pins provides access to the extra I/O signals provided

by the PIC32 microcontroller.

The microcontroller system uses logical pin numbers to identify digital I/O pins on the connectors. The logical pin

numbers for the I/O pins on the Max32 are 0 – 85. These pin numbers are labeled in the silk screen on the board.

The analog inputs on connectors J5 and J7 are also assigned digital pin numbers. Pins A0 – A7 on connector J5 are

digital pins 54 – 61, and pins A8 – A15 on connector J5 are digital pins 62 – 69.

Pin numbers 70 – 85 are on the inner rows of connectors J14 and J3.

3. 5 Peripheral I/O Functions

The PIC32 microcontroller on the Max32 board provides a number of peripheral functions. The following

peripherals are provided:

UART port 0: Asynchronous serial port. Pin 0 (RX0), Pin 1 (TX0). These pins are connected to I/O connector J14 and

are also connected to the FT232R USB serial converter. It is possible to use these pins to connect to an external

serial device when not using the USB serial interface. This uses UART1A (U1ARX, U1ATX) on the PIC32

microcontroller.

UART port 1: Asynchronous serial port. Pin 19 (RX1), Pin 18 (TX1). This uses UART1B (U1BRX, U1BTX) on the PIC32

microcontroller.

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