Firstly a quick intro… I’m an electronics engineer working in the professional broadcast industry with a fairly significant background in both board-level and FPGA design. I received my Raspberry Pi a little while ago and immediately became interested in developing a simple plug-on board to expand it’s basic I/O capability and add a few extra features. Initially just for my own interest but I started to think maybe there’s a few others out here that might like one…
So I’ve come up with the PiXi board… So named because it uses a Xilinx FPGA to expand the I/O through a connection to the existing I/O port (P1) on the Raspberry Pi.
The PiXi board offers two 24 port GPIO connectors, one of which is basically 24 user-configurable I/O pins. The second GPIO connector offers 8 open-collector (pull to GND) 2amp drivers, 8 open-collector (PULL to V+) 2amp drivers and 8 user-configurable I/O (as in GPIO1). The pins are arranged on the connector so that GPIO2 can also directly connect to upto 8 servos of the kind used in R/C vehicles to provide 8 PWM servo (or speed control) drivers.
The board also has an oscillator (frequency is TBD), an interface designed to drive a vacuum fluorescent display, a small EEPROM memory (size is TBD) a fan connector with PWM control & spin status and a temperature monitor (TBC).
I’m also looking at adding multi-channel analogue to digital and digital to analogue converters if there's enough interest and I can do this without adding to the cost too much.
In fact there’s a whole heap of things I could add to this board at this stage, smart-phone based accelerometers, magnetometers & GPS for a few ideas, but I’m trying to keep the cost down. If it’s of interest to many people here then I’d plan to put this into production. I’ve worked in the electronics industry for many years and I have excellent contacts in the electronics manufacturing industry and believe I can get some prototypes together soon.
One of the main ideas behind this board was that it would offer the user the ability to learn about digital electronics, FPGAs, and develop their own FPGA using VHDL or Verilog based FPGA design tools. The reason I’ve chosen a Xilinx FPGA is that Xilinx offers a ‘WebPack’ tool that is freely available on the Xilinx website which will allow a user to complete design an FPGA at no extra cost. Programming the FPGA would be done through the Raspberry Pi GPIO using a simple programming executable. I should perhaps stress at this point that I'm not employed by Xilinx, I just like using them!
A basic block diagram of the board is available at http://www.cantrills.com/astro-designs/ ... xi-200.pdf
Assuming I can get this production (if there’s enough interest), this board would be offered ready assembled and fully tested for a purchase price of around £25 - £35. That’s the target at least…
So I’ll stop waffling now and open this up for comment… What do you think, would anyone here be interested in one for £25-£35?
Also, is there anything in particular anyone would like to see added to the specification?