Recently I have encountered a strange issue I cannot really explain...
I have a firmware that manages serial UART communication with a callback that has a state machine with 3 states.
In the first state, UART is set to perpetually expect 1 byte of data until a specific value is received. If the value is received, another byte is set to be read via UART_Receive_IT and SM proceeds to the next state.
In the second state, the received byte is considered message length and UART_Receive_IT is set to read the expected amount of bytes.
The third state is supposed to happen when the expected amount of bytes is received and all parsing is done... however, it is never triggered when the serial data is longer than 49 bytes.
I am sending data with RealTerm. Short messages work just fine, but then I need to send 147 bytes. In the debug, I can see from the state of huart2 handler that RxXferCount starts at 147 and decrements until 98. Then, UART_RxISR_8BIT is never called again, the state remains unchanged until firmware's timeout triggers and aborts the reception.
I tried to look at some other things. RTS and CTS pins are low at the time when timeout happens. The timeout was initially 0.02s, I raised it to 1s with no effect. Overrun flag is low as well. My buffer is larger than the message I am expecting. I tried to use UART_Receive_IT in batches of 32 bytes, but then the first batch is received correctly and the second batch freezes in the similar way as soon as the total amount of received bytes reaches 49. I am not supposed to reset something between UART_Receive_IT calls, correct?
Why UART might just stop receiving data? What else can I do to try debug this?
