I did a small thing for Element 14. I volunteered to answer questions about their chipKIT Pi. This is a small ChipKIT device that plugs directly into a Raspberry Pi. Element 14 compiled the MPIDE to run on a Raspberry Pi so all development for the chipKIT Pi could be done on the Raspberry Pi. This makes it very easy to make changes and test them on the Raspberry Pi. I thought the board was a great idea adding to the abilities of the Raspberry Pi.
I noticed that the chip used on the chipKIT Pi was a PIC32MX250F128. This is a very interesting part it is a 32 bit part from Microchip. It runs at 3 volts and interfaces directly with the Raspberry Pi without any interface chips or level shifters. The part also has a USB port that isn’t used by the Raspberry Pi. The Raspberry Pi programs the PIC through a serial port.
I looked through the boot loaders for the PIC32MX250F128 on the Digilent site and found a boot loader for the part that used the USB port. I thought I could build a small board with the PIC32MX250F128 on it that could be programmed with the MPIDE. I took a Blue Bird board and put a PIC32MX250F128 on it. I had to add a crystal but I got it to work. Added the USB boot loader and was able to program the device with the MPIDE. The Wolf board was born.
This part requires an 8 meg crystal to run. I put that crystal on the bottom of the board so I wouldn’t disturb the layout on the top of the board. I ran the auto router and was able to clean up a couple of lines, then finished the layout, and sent it to OSH Park to have boards fabricated.
I got the boards back in a couple of weeks and they worked right off the bat. I didn’t have to do any debugging and they worked great.