One thing that someone else might find useful while debuggin open-source-silicon.dev #mpw-6plus-silicon

One thing that someone else might find useful whil...

Maximo Balestrini

01/16/2024, 7:57 PM

One thing that someone else might find useful while debugging your chips is soldering a header and using a jumper on J2. When J2 is shorted Caravel's serial port gets connected to the FTDI chip, and you can use a serial terminal program like picocom to receive data from Caravel on your pc. The downside is that you can't flash the firmware while J2 is shorted. That's why I use a jumper.

👍 4

Maximo Balestrini

01/16/2024, 8:06 PM

And if you are trying to read serial data from Caravel, just reading the

reg_uart_data

won't work (you keep reading the first char you send). You need to clear the receive event. I use this functions: https://github.com/efabless/caravel_mgmt_soc_litex/blob/main/verilog/dv/firmware/APIs/uart_api.h Caravel docs don't mention this. Maybe it's something related to the change from PicoRV to VexRiscC https://caravel-harness.readthedocs.io/en/latest/uart.html

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Matt Venn

01/22/2024, 4:15 PM

just tested that, works nicely

👍 1

Maximo Balestrini

01/23/2024, 3:47 PM

Here's some sample code that outputs the state of Caravel's IOs to a terminal to use for debugging purposes: https://gist.github.com/mbalestrini/5cb4ed6b369dd6bb2775b3fffb773674

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Victor Munoz

08/02/2024, 7:23 AM

Hi Maximos, So does UART_readChar() work for you? I have the same behavior that you describe; it keeps reading the first byte received. It seems that clear the event using the CSR doesn't work in the CLEAR FPGA management.

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