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Welcome to the I2CMatrix wiki!
This is my first project, designed to gain an understanding of the LogiPi FPGA development board for the raspberry Pi. The LogiPi board 'piggy backs' on the Raspberry Pi, connecting directly to the Pi GPIO header.
The project basically writes a stream of characters to an 8x8 LED matrix. See the video demo here
The project comprises 3 main parts as follows:
- The circuit design for connecting the MAX7219 to the 8x8 LED Matrix and to the output pins of the LogiPi.
- The FPGA firmware, written in VHDL which converts the Raspberry Pi I2C Interface to the SPI compatible MAX7219 Interface. This firmware is compiled to create an image file which can then be uploaded to the LogiPi FPGA creating a hardware instantiation of the I2C to MAX7219 Interface.
- The Python script that takes user input (text) and streams the ascii characters column by column to the Raspberry Pi I2C bus.
The FPGA firmware was created in Xilinx ISE Project Navigator 14.7 which is free to use. The firmware design receives data from the Raspberry Pi I2C Interface (SDA = GPIO2 & SCL = GPIO3) and converts this to the MAX7219 (8 digit LED display driver) SPI compatible interface (PMOD1 Pin 3 = MDIO, PMOD1 Pin 4 = MDC & PMOD1 Pin 7 = MDIOLoad).
You can of course, send data direct from the Raspberry Pi to the MAX7219 using the Pi's native SPI interface, but as previously stated this project was designed to help gain an understanding of the LogiPi and run through a design flow using Xilinx ISE.
Equipment / Environment
Raspberry Pi 2 with Raspbian OS
LogiPi from Element 14. LogPi Manual
FPGA IDE = Project Navigator v14.7 (Linux 64 bit)
Python IDE = [Pycharm Community Edition 2016.2](https://www.jetbrains.com/pycharm/specials/pycharm /pycharm.html?&gclid=CKfZ6O-hktECFY5WDQodUXkMHA&gclsrc=aw.ds.ds&dclid=CKS39O-hktECFY0LDAodcYYOjQ)
Logic Ananlyser = Arduino Sump Compatible logic analyser
8x8 LED Matrix from Adafruit
MAX7219 IC. MAX7219 Data Sheet