It is random. So in a 50-ish byte packet I will see sequences of missing bytes which can be 1, 2 or event 3 bytes long missing.
For example, I am seeing on the logic analyser the ESP sending the following hex bytes: c0 01 08 04 00 07 12 20 55 00 00 00 00 c0 NuttX is seeing: c0 01 04 20 55 00 00 c0 Regards, Mark — Mark Stevens mark.stev...@wildernesslabs.co > On 9 May 2024, at 14:56, Nathan Hartman <hartman.nat...@gmail.com> wrote: > > On Thu, May 9, 2024 at 3:31 AM Mark Stevens > <mark.stev...@wildernesslabs.co.invalid> wrote: > >> So we have a two chip board: >> >> * STM32 running NuttX (v7.5 I believe) >> * ESP32 acting as a coprocessor running custom firmware >> >> The STM32 runs the show and the ESP32 provides services to the STM32 code. >> >> In normal run mode, NuttX has a kernel thread that reads data from the >> ESP32 over UART (/dev/ttyS2) and then processes the data. This is working >> fine as is. >> >> The UART is configured to use a 512 byte buffer. >> >> Every now and then we want to upload new firmware to the ESP32. This is >> done by a user mode thread and it goes through the following steps: >> >> * Signals to the kernel thread that it should close the UART and exit. >> * Opens the serial port >> * Starts the programming sequence >> >> If we try to do this then the user mode thread misses bytes in the byte >> stream. >> >> Kernel mode thread only: >> When the system starts then this thread works fine, no bytes are lost. >> >> User mode thread only: >> If we do not start the kernel mode thread then the programming works fine, >> no bytes are lost. >> >> Both threads: >> Starting the kernel works fine, we do not miss any bytes. The kernel >> thread can be stopped, the UART is closed correctly. >> >> The user thread can open the serial port correctly after the kernel thread >> has stopped but now it misses bytes. >> >> So we know the individual threads work as expected when used on their own >> but not together. >> >> How anyone seen this or have any advice on how we can resolve the issue? >> >> Regards, >> Mark >> ______________________________ >> mark.stev...@wildernesslabs.co >> >> >> >> > > Which bytes are missing? Are they the ones at the beginning of the message, > or the end? > > Nathan
