Digilent 410-269P-KIT - Manual (Page 5)

chipKIT Cmod™ Reference Manual
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Page 5 of 11
The DIP connector uses standard DIP package pin numbers. Pins 1- 20 count up from the square pad labeled ‘1’ on
the lower DIP connector. Pins 21-40 count up from the pin near the label ‘Q1’ to the pin labeled ‘GND’ on the other
DIP connector.
Pins 18 and 19 are normally the reference voltages for the microcontroller’s A/D converter, but can also be used as
digital I/O pins.
In addition to the connector pin, Pin 14 is also connected to the user LED LD3. Pin 12 also connects to the user LED
LD4.
In addition to digital I/O, there are analog inputs available on the board, called A0 through A12. These pins are
shared with digital pins 12, 13, and 16 through 26. Refer to the attached pinout tables for the correct mapping of
these signals.
Peripheral I/O Functions
The PIC32 microcontroller on the chipKIT board provides a number of peripheral functions. The following
peripherals are provided:
I
2 C: Synchronous serial interface. The I2C1 interface is available on pins 4 (SDA1) and 38 (SCL1). The I2C2 interface
is available on pins 22(SDA2) and 23(SCL2). Note that when using MPIDE, the only available I 2 C interface is I2C1.
Note: The I 2 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 chipKIT Cmod board and must be provided 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.
User LEDs: Pins 12 (LD4) and 14 (LD3). Both Pin 12 and Pin 14 are shared between a connector pin on the chipKIT
Cmod and an LED. Driving the pin high turns the LED on, driving it low turns it off.
External Interrupts: Only INT0 is hard-mapped on the microcontroller. It is connected to Pin 37 of the chipKIT
Cmod. The other external interrupts are accessible via PPS described below.
A/D Converter Reference: Pin 18 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 18.
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. A reset button is located on the right side of the board. Pressing this button resets the
PIC32 microcontroller.
Reset of the PIC32 microcontroller can be initiated by the USB serial converter. The USB serial converter brings the
DTR pin low to rest the microcontroller. The P32_RST net is connected to Pin 9 of the DIP package. This allows
external circuitry to reset the microcontroller, or to ensure that the circuitry is reset at the same time as the
microcontroller.