Cornell University ECE4760
Development Boards
PIC32MX250F128B

Introduction

There are two target boards which were created by Sean Carroll:
--- The first is large and intended to be used for the lab exercise part of the course.
--- The second board is small and is intended to be a CPU carrier for final projects and other space-limited uses.
Both boards are programmed using a PICkit 3 programmer/debugger, or by tapping the programming signals
from a Microstick2 (see below).

The large board

The large board features a port expander, DAC, TFT socket, programming header, and power supply.
-- Assembly instructions
-- Large board schematic and layout (ExpressPCB format)
-- Using the Port Expander and ZIP code (Sean Carroll)
-- Using the TFT LCD
-- SPI and DAC

An example uses Protothreads 1.2.1 to drive the TFT-LCD, on-board LED and DAC. The example displays some graphics, blinks the LED at 0.5 Hz and outputs a 24.4 Hz sawtooth from the DACA (DAC channel A) output pin. SPI channel 1 runs the TFT, SPI channel 2 runs the DAC. Pin RA0 is attached to the LED. (code, ZIP)

PIC32 i/o pins used on big board, sorted by port number. Any pin can be
recovered for general use by unplugging the device that uses the pin.
SPI chip select ports have jumpers to unplug.
----------------------------
RA0 on-board LED. Active high.
RA2 port expander intZ
RA3 port expander intY

RA4 PortExpander SPI MISO
-----
RB0 TFT D/C
RB1 TFT-LCD SPI chip select (can be disconnected/changed)
RB2 TFT reset
RB4 DAC SPI chip select (can be disconnected/changed)
RB5 DAC/PortExpander SPI MOSI
RB9 Port Expander SPI chip select (can be disconnected/changed)
RB11 TFT SPI MOSI
RB14 TFT SPI Sclock
RB15 DAC/PortExpander SPI Sclock
----------------------------

The small board

The small board is stripped down to just a MCU and power supply.
The intention is that this board can be built into projects easily.
-- Assembly instructions.
-- Small board schematic and layout (ExpressPCB format)

An example uses Protothreads 1.2.1 to drive two LEDs connected to RA0 and RB0, see picture in the
microstick2 programming section below. (code, ZIP)

Microstick2 as a programmer

The connections to the microcontroller socket on the Microstick2 act like the
standard programming signals from the PICKIT3, which was used to develop the boards you will build.
On both boards, J1 marks pin1 of the 6-pin ICSP header.
Note that for the pins shown, the programming selector switch on the Microstick2 must be set to position A.

Signal PICkit3 (ICSP)
connector on board
Microstick2
DIP Pins
MCLR 1 1
ground 3 27
prog data (PGD) 4 4
prog clock (PGC) 5 5

A wiring example is shown below. Note that pin 1, MCLR, is only available on the Microstick2 DIP socket as shown.
Also note that the programming selector switch on the Microstick2 must be set to position A.
When you click on the small images, you will get enlargments with the pin numbers indicated. For systems that do not
draw too much power, you could attach the VDD output from the Microstick2 to pin 2 of the programming header to provide
power, BUT ONLY IF you do not connect any other power to the big or small board.

Another example with the small board.

 

Resources


Copyright Cornell University June 30, 2017