Tuesday, September 6, 2011

My own first PIC32 Development Board

Here is a USB PIC32 development board that is in progress.  I bought a bare 64-pin PIC32MX795F512H which is the highest end Microchip 32-bit CPU, except for having 36 fewer pins pins than its close sibling.  This CPU has 512K Flash, 128K RAM, and runs at 80MHz.

It was soldered to a breakout board that is connected by dual row 0.1" 16-pin headers so it can be mounted in sockets on a standard solder breadboard.  It has three symmetrical 8 pin headers which expose shared SPI/UART (total of 6 RX/TX pairs), and power lines.  Jumpers choose between USB host and USB device functionality.
The first test of this board was as a four port RS-485 monitor.  I was able to enhance the monitor's protocol to support four sources, then enhanced it as a bidirectional adapter.  The code is built on Microchip's USB device CDC sample and shared among various PIC targets, so the code is also supported on other various 8-bit and 16-bit PICs too.

A planned test is to breakout the RMII/MII lines to an Ethernet PHY and test the Ethernet capability of this CPU.  I purchased a QFN 36-pin SMSC LAN8700 PHY but unfortunately I cannot find a compatible breakout board for it.  Nine pin sides seem to be an odd number, and the breakouts I have tried are built for even numbered pins per side making this one just a bit too small to work with the traces.  My next plan is to try a QFN 24-pin SMSC LAN8720 PHY.

Another plan is to get it to work with the chipKIT Arduino-Compatible Prototyping Platform so it can be programmed in C++.

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