ESP32 Forum

Hello.
When testing the ESP32 UART, I found that the reception of long packets occurs in parts of 120 bytes maximum. This happens with different methods of reception, which I tried (event or interrupt). This occurs when the example uart_events. This situation is undesirable when implementing MODBUS, where the packet length is a maximum of 256 bytes. and there are strict limits on the time between the bytes and the frames of the Protocol.

I'm pretty sure this is because of the FIFO size in the UART of the ESP32. Quick hack is to make that larger, but really, you should do proper packet assembly yourself.