LoPy UART shifted trame from one LoPy to another one

[Adil.L]

Hi everybody,

I'm working on a LoRa GPS tracker project. However, I get some trouble when I try to communicate over a UART communication between two LoPy's. You can find on the figure above an illustration of the problem and of my scripts.

As you can see, I send a 'a' character which correspond to a '01100001' in the binary ASCII coding and I receive a hexadecimal 'b0' which correspond to '10110000' in binary. It seems that the sent frame is shifted to the right and a 1 is added as the most significant bit. Finally, the weirdest thing is that it perfectly works when I choose the number of stop bit equal to 1 and I completely do not understand why.

Thanks you and good evening.

[jmarcelino]

I saw this commit in ESP-IDF logs today and remembered this thread.

https://github.com/espressif/esp-idf/commit/5d5b625d0e9d266e66f059d5655dc2e9590aca0e

Looks like 2-stop bit mode should be fixed soon.

[jmarcelino]

I think the the uart fixes from esp-idf main repo need to be merged to the pycom-esp-idf fork, it's a couple of versions behind.

[Shaun]

@Adil.L
It looks to me that you have exposed a fw bug when using 2 stop bits.