Uart Interface - Digilent chipKIT MX3 Reference Manual

chipKIT™ MX3 Board Reference Manual
#pragma config FPLLODIV = DIV_1
#pragma config FPBDIV = DIV_8
Documentation for the available PIC32 configuration variables can be found in the PIC32MX Configuration Settings
guide. This is found using the "Help.Topics..." in the MPLAB IDE. Refer to Appendix E for an example of setting the
configuration variables.
When using the chipKIT MX3 with the MPIDE software, the clock source is automatically set by the boot loader and
no action is required.
6

UART Interface

The PIC32MX320 microcontroller provides two UART interfaces, UART1 and UART2. The UARTs can provide either
a 2-wire or a 4-wire asynchronous serial interface. The 2-wire interface provides receive (RX) and transmit (TX)
pins. The 4-wire interface includes request-to-send (RTS) and clear-to-send (CTS) in addition to receive and
transmit.
UART1 can be accessed from Pmod connector JB and UART2 can be accessed from Pmod connector JC using the
following pins:
 U1CTS
JB-01
 U1TX
JB-02
 U1RX
JB-03
 U1RTS
JB-04
 U2CTS
JC-01
 U2TX
JC-02
 U2RX
JC-03
 U2RTS
JC-04
Some of the pins on UART1 and SPI1 are shared on the PIC32 microcontroller. This means that UART1 and SPI1
can't both be used at the same time.
Detailed information about the operation of the UART peripherals can be found in the PIC32 Family Reference
Manual, Section 21, UART.
The USB Serial converter is connected to UART1. The MPIDE uses this to communicate with the boot loader. This
can also be used for a serial communications interface between the chipKIT MX3 board and other software running
on a PC. Resistors are used to decouple the USB serial interface and so UART 1 can also be used via Pmod
connector JB.
Note that when using the MPIDE software, devices connected to JB can interfere with the operation of the serial
interface and prevent the MPIDE from successfully downloading sketches to the board. If this happens, disconnect
the external device from JB until the sketch has been downloaded and then reconnect it.
When using the chipKIT MX3 with the MPIDE and the chipKIT system, the UARTs are accessed using the
HardwareSerial facility built into the system. UART1, connector JB, is accessed using the Serial object and
UART2, connector JC, is accessed using Serial1.
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