well I've given up and fallen back on bitbanging, seems that using a bit timing of 200us has worked, maybe other timings work too. I think the problem is the tx line was holing the line HIGH so the attiny couldn't respond and pull the line low. I'm sure it's possible with the hardware uart but from ...

So, after further investigation, I believe the issue is still line contention even with the code given before.

I believe this is back on track with the thread purpose, a combined rx/tx line that alternates between rx and tx.

Is there anything we are missing with the uart initialization or control?

So I have way too many details to cover here, but I think I am pretty confident the issue is still line contention. I am sending the exact same break + updi commands in the exact same serial format as jtag2updi but I don't get a response. I thought I would test something, I connected jtag2updi in to...

Just to be clear, the original advice about open drain helped me significantly which was indeed related to the thread. But yes, discussing the updi break is probably outside the scope of this thread. Although, I wonder if maybe RandomInternetGuy fell prey to the pagination and opened this 7 year old...

Bump, after some insight from another thread I feel I may have sorted out what is effectively half-duplex by merging a tx/rx line together and then doing something like this: // UART configuration uart_config_t uart_config = { .baud_rate = UPDI_BAUD, .data_bits = UART_DATA_8_BITS, .parity = UART_PAR...

Thank you tremendously, I've finally gotten some time to sit down and try this and it seems your advice has helped me gain some progress. So, with this code below, I am able to connect both my rx and tx lines together and then connect them into an active connection from jtag2updi and snoop it's updi...

You should be able to route the RX and TX signals of the UART to the same pin via the GPIO matrix (using esp_rom_gpio_connect_out_signal()/esp_rom_gpio_connect_in_signal() ). At least on a -C3 this works. Both signals can be connected to the pin alternatingly or at the same time. In the latter case...

I am trying to create a updi programmer out of an esp32-c3-mini and I am able to configure the hardware uart like this and I can snoop on UPDI commands sent by things like jtag2updi successfully. uart_config_t uart_config = { .baud_rate = UPDI_BAUD, .data_bits = UART_DATA_8_BITS, .parity = UART_PARI...

bump, I am also trying to do this and having trouble, does anybody have any example of this?