Datasheet

chipKIT™ Wi-FIRE™ Board Reference Manual

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both device and host operation of PIC32 microcontrollers. These reference designs can be modified for developing

USB firmware for the Wi-FIRE.

9 SD Card Interface

The micro-SD card connector provides the ability to access data stored on micro-SD sized flash memory cards using

the SD card library provided as part of the MPIDE software system.

The SD card is accessed using an SPI interface on PIC32 microcontroller pins dedicated to this purpose. The MPIDE

SD library uses a “bit-banged” software SPI implementation to talk to SD card. However, software can be written to

access the SD card using SPI3.

On the Wi-FIRE board, SPI3 and I/O pins used to communicate with the SD card are dedicated to that function and

are not shared with other uses.

10 Peripheral I/O Functions

The PIC32 microcontroller on the Wi-FIRE board provides a number of peripheral functions. The provided

peripherals are explained in the following sections.

10.1 UART Ports

UART 4: Asynchronous serial port. Pin 0 (RX), Pin 1 (TX). This is accessed using the runtime object: Serial. These

pins are connected to I/O connector J10 and are also connected to the FT232RQ USB serial converter. It is possible

to use these pins to connect to an external serial device when not using the FT232RQ USB serial interface. This

uses UART4 (U4RX, U4TX) on the PIC32 microcontroller.

UART 1: Asynchronous serial port. Pin 39 (RX), Pin 40 (TX). This is accessed using the runtime object: Serial1. This

uses UART1 (U1RX, U1TX) on the PIC32 microcontroller.

10.3 SPI

Synchronous serial port. Pin 10 (SS), Pin 11 (MOSI), Pin 12 (MISO), Pin 13 (SCK). This can be accessed using the SPI

standard library. It can also be accessed using the DSPI0 object from the DSPI standard library. This uses SPI2 (SS2,

SDI2, SDO2, SCK2) on the PIC32 microcontroller. These signals also appear on connector J7. Be aware that pin 13

(SCK) is shared with USER LED1, and that both LED1 and the SPI port cannot be used concurrently.

SPI1: Synchronous serial port. This is an additional SPI interface on the PIC32 microcontroller that can be assessed

using the DSPI1 object from the DSPI standard library. SS1 is accessed via digital pin number 7. SDO1 is accessed

via digital pin 35. SDI1 is accessed via digital pin 36. SCK1 is connected to digital pin 5.

10.4

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Synchronous serial interface. The PIC32 microcontroller shares analog pins A4 and A5 with the two I2C signals, SDA

and SCL. This uses I2C4 (SDA4, SCL4) on the PIC32 microcontroller. Both SDA4 and SCL4 are accessible on

connector J6.

Note: The I2C bus uses open collector drivers to allow multiple devices to drive the bus signals. This means that

external pull-up resistors must be provided to supply the logic high state for the signals.