Digilent chipKIT Uno32 Reference Manual - Page 10

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chipKIT Uno32 Reference Manual

device when not using the USB serial

interface. This uses UART1 (U1RX, U1TX) on

the PIC32 microcontroller.

UART port 2: Asynchronous serial port. Pin 39

(RX), Pin 40 (TX). This uses UART2 (U2RX,

U2TX) on the PIC32 microcontroller.

SPI: Synchronous serial port. Pin 10 (SS), Pin

11 (MOSI), Pin 12 (MISO), Pin 13 (SCK). This

uses SPI2 (SS2, SDI2, SDO2, SCK2) on the

PIC32 microcontroller These signals also

appear on connector J8.

Jumpers JP5 and JP7 are used to select

whether the Uno32 operates as a Master

(transmit on MOSI, receive on MISO) or a

Slave (transmit on MISO, receive on MOSI)

device. The shorting blocks on JP5 and JP7

are normally placed in the Master position for

the Uno32 to function as an SPI master.

Jumper JP4 is used to select PWM output or

the SPI SS function on Pin 10. The shorting

block on JP4 should be in the RD4 position to

select PWM output. It should be in the RG9

position to select the SPI SS function.. JP4 will

normally be in the RD4 position. In general, the

only time it needs to be in the RG9 position is

when the Uno32 board is being used as an SPI

slave device.

C: Synchronous serial interface. The PIC32

microcontroller shares analog pins A4 and A5

with the two I

C signals SDA and SCL.

Jumpers JP6 and JP8 are used to select

whether the analog pin functions or the I

functions are being used. The shorting blocks

are placed in the A4/A5 position to select the

analog input function or general digital I/O.

They are placed in the RG3/RG2 position to

use the pins for I

C operation. This uses I2C1

(SDA1, SCL1) on the PIC32 microcontroller.

Note: The I

C bus uses open collector drivers

to allow multiple devices to drive the bus

signals. This means that pull-up resistors must

be provided to supply the logic high state for

the signals. These pull-up resistors are not on

the Uno32 board and must be provided

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externally. The required resistance of the pull-

up resistor to use depends on the total number

of devices on the bus, the length of wire, and

the clock speed being used. It essentially

depends on distributed capacitance on the

bus. The higher the distributed capacitance

and the faster the clock speed, the smaller the

resistance should be. Values typically used are

in the range of 2K to 10K ohms.

PWM: Pulse width modulated output. Pins 3

(OC1), 5 (OC2), 6 (OC3), 9 (OC4), and 10

(OC5).

External Interrupts: Pin 38 (INT0), Pin 2

(INT1), Pin 7 (INT2), Pin 8 (INT3), Pin 35

(INT4)

User LEDs: Pin 13 (LD4), Pin 43 (LD5). Pin 13

is shared between a connector pin and the

LED. Pin 43 only goes to the LED and not any

connector pin. Driving the pin high turns the

LED on, driving it low turns it off.

A/D Converter Reference: Labeled A, the left-

most outer pin on connector J5. This is used to

provide an external voltage reference to

determine the input voltage range of the

analog pins. The maximum voltage that can be

applied to this pin is 3.3V. This pin can also be

used as digital pin 42.

RTCC: Real Time Clock Calendar. The PIC32

microcontroller contains an RTCC circuit that

can be used to maintain time and date

information. The operation of the RTCC

C pin

requires a 32.768Khz frequency source.

Crystal X2 (not loaded), just above and to the

right of the PIC32 microcontroller IC, is

provided for you to solder a 32Khz watch

crystal. The Citizen CFS206-32.768KDZF-UB

crystal can be used in this location.

RESET: The PIC32 microcontroller is reset by

bringing its MCLR pin low. The MCLR pin is

connected to the P32_RST net on the circuit

board.

As described earlier, reset of the PIC32

microcontroller can be initiated by the USB

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