Alchitry Cu Serial Interface

[rrc]

Hi,
in the schematic I can see, that two pins of the ICE40 are connected as RxD and TxD to the FTDI chip. Is this a serial interface to communicate the FPGA?
If yes: how do I connect to on PC side? The FTDI did not appear as /dev/tty* device on my Linux machine.

-RRC

[iggyglass]

Hi,
in the schematic I can see, that two pins of the ICE40 are connected as RxD and TxD to the FTDI chip. Is this a serial interface to communicate the FPGA?
If yes: how do I connect to on PC side? The FTDI did not appear as /dev/tty* device on my Linux machine.

-RRC

I'm not sure how to do it, however my intuition is that you need to make the serial port actually do something. Looking at the code in au_top.luc (it should be similar enough to cu_top.luc) it looks like by default it simply echos the incoming serial data making the computer that it's connected to think that its not actually connected to anything worth sending data to.

[rrc]

I did some research: The FTDI can be controlled via the libftdi library. For quick and dirty stuff there is also a python package called pylibftdi that is based on the library.

The FTDI has two interfaces A to flash the Cu and B to communicate with the FPGA.

So the Device has to be initalized as follows (in python):

Code:

from pylibftdi import Device

device = Device(interface_select=2)

Then I was able to send/receive to/from the FPGA with the read() and write() methods.
The baudrate can be changed with

Code:

device.baudrate = 300

to 300 Baud in this example.

The Python package is documented at https://pylibftdi.readthedocs.io/en/0.15...bftdi.html
And the library at https://www.intra2net.com/en/developer/l...mentation/