PmodUSBUART

[Jed Brody]

I'm attempting to send data from a BASYS 2 to a computer using the PmodUSBUART, but it appears to never send; neither LED on the Pmod ever lights up.  I'm certain that the circuit on the FPGA is correct (I'm using Example 33 from Haskell and Hannah, Learning by Example Using Verilog:  Advanced Digital Design) because if I wire my output pin to an Arduino, the computer can read the data through the Arduino.  But if I use the same pin as TXD on the Pmod, the computer doesn't seem to receive anything.  I've tried both 0 and 1 on RTS.  Any suggestions?  Thanks.

[D@n]

Well ... okay, I've got one of those working on my desk, so I might be able to offer a touch of advice.

1. RTS is an input.  CTS may be set to '1'.
2. Double check the power.  If you are not powering your board via the USBUART, then make certain the jumper setting reflects this fact.
3. Be aware that the TXD and RXD pins are with respect to the chip on the USBUART, not your FPGA chip.  (This applies to RTS and CTS as well ...)

And ... let's see if that helps.  If not, please write back.

Dan

 

[Jed Brody]

Thank you!!!  That fixes it.  I thought the pins were with respect to the FPGA.