Matlab and FTDI

Question

I am trying to send/retreieve data from/to FPGA using Matlab. I connected FPGA using Virtual com port. Now how to send data from Matlab to FPGA or read data of FPGA ?

FTDI 2232H is on the FPGA as well. I connected external LED's and switches on the I/O ports of the FPGA.

I am new in this field, so want some guideline to start communication b/w MAtlab and FPGA:

I tried following code:

  s1= serial('COM9')
  fopen(s1)

. Is it the right way to communicate ? Kindly guide. thanks

Answer 1

FPGA's are configured using a Hardware Description Language (HDL) such as Verilog or VHDL. These languages let you specify how the switch configuration within the FPGA, which in turn lets you construct your custom digital logic and processing system.

The HDL Coder Toolbox in Matlab lets you design and prototype your custom logic using higher-level functions, which are then translated into HDL and can be be used to directly program your chip. This tutorial describes the process in detail.

If you already have a design implemented on your FPGA and want to communicate with that implementation, you would use Matlab's serial port communication functions. The exact protocol will depend on the interface you have implemented.

Some intermediate debugging steps I find helpful:

1. Verify that you can send serial port data from your computer. In Windows XP, you can do this easily with HyperTerminal, and hooking up a scope to the output pins of your serial cable. Set up a trigger to capture the event. For Windows 7 and newer, you'll need to download a HyperTerminal client.
2. Repeat this same process with Matlab. Using a scope, verify that you see the serial port signal when sent from Matlab, and that the output matches the results from step 1. Again, set up a scope trigger to capture the event.
3. Now connect the serial cable directly to the FPGA board. Modify your HDL to include a latch on the serial input that displays the output on the LED's. Verify that your board initializes to the correct LED state, and that the LED state changes when you send the serial message.
4. Lastly, verify that you are interpreting the message correctly on the FPGA side. This includes making sure that the bit-ordering is correct, etc. Again, the LED outputs can be very helpful for this part.

The key here is to take small, incremental steps, physically verifying that things are working each step of the way.