Digilent 410-280P-KIT - Manual (Page 6)

chipKIT DP32
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Due to the internal USB circuit on the PIC32MX250F128B requiring 5VDC to operate, the USB
hardware is only operational when powering off of USB. Do not attempt to power the USB circuitry
with the external power screw terminal, unless it is a regulated 5V external power supply.
5V Compatibility
The PIC32 microcontroller operates at 3.3V. There are two issues to consider when dealing with 5V
compatibility for 3.3V logic. The first is protection of 3.3V inputs from damage caused by 5V signals.
The second is whether the 3.3V output is high enough to be recognized as a logic high value by a 5V
input.
Only MIPDE pin numbers 0 - 3 on the PIC32 microcontroller are 5V tolerant all other pins are 3.3V
tolerant only. To provide 5V tolerance on those pins, you will have to add clamping diodes and current
limiting resistors to those pins. Please check the table 1 in appendix A to confirm 5V tolerant pins.
The minimum high-voltage output 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
typically be close to 3.3V. Some 5V devices will recognize this voltage as a logic high input, and some
will not you will have to read the datasheet for the 5V parts you are using to ensure that 3.3V will
satisfy the logic high conditions for the part. Many 5V logic devices will work reliably with 3.3V inputs.
Input/Output Connections
The DP32 board provides all 19 I/O pins of the PIC32MX250F128B microcontroller to through-hole
points on the PCB.
The PIC32 microcontroller can source or sink a maximum of 7mA on all digital I/O pins. The maximum
current that can be sourced or sunk across all I/O pins simultaneously is +/- 200mA. For more detailed
specifications, refer to the PIC32MX1XX/2XX Data Sheet available from the Microchip web site.
The DP32 uses logical pin numbers to identify digital I/O pins. Pins 0 through 8 are located on J4,
counting up from the square pad of J4. Pins 9 through 18 are located on J3, counting up from the
square pad. In addition, several of these I/O pins share functionality with other devices on the board
see table 1 in appendix A for more information.
Pins 15 and 16 are shared with the crystal for the internal oscillator, and are not typically usable. Pin 6
is shared with the Analog Temperature Sensor. Pin 8 is shared with the onboard Potentiometer. Pins
4 and 5 are shared with the USB Data+ and Data- signals. Pin 0 is shared with the USBID function,
but removing jumper 1 clears this conflict. Pins 9, 18, 7, and 10 are used for the SPI EEPROM device
if it is loaded, on its Chip Select, Master Out/Slave In, Serial Clock, and Master In/Slave Out lines
respectively.
In addition to the digital I/O, there are Analog inputs available on the board, called A0 through A8.
These pins are shared on digital pins 6 thru 14.
Peripheral I/O Functions
I
2 C: Synchronous serial interface. The I2C1 interface is available on pins 2 and 3. When using the I 2 C
interface, it is necessary to set JP4 and JP5 such that pullups are present on the bus this is done by
moving the jumpers to pins 2 and 3 on each jumper.