OTA: Passing incoming serial stream to Update.writeStream()

thesmike · May 26, 2020, 11:39am

I want to program an ESP32 from another MCU (MT3620) using the arduino OTA functionality in Update.h
I am already able to communicate between the MCUs using UART.

The idea is, to set the esp32 in a specified "firmware receiving state" in which I would do (after checking size with Update.begin()):

Update.writeStream(Serial2);

The problem is, that I don't know when and how to stop passing the stream to Update.writeStream() and continue with further processing (e.g. checking the md5 of the received image).

In theory, when the MT3620 has sent the full firmware image, I would send any defined end marker which signals, that the image has fully been transferred. Then I would send another message with the md5 of the firmware to confirm it on the esp32.

How can I detect the right point to stop forwarding the stream to Update.WriteStream() and continue processing the Serial2 input stream to my normal message handling routine?

Juraj · May 26, 2020, 12:08pm

github.com

espressif/arduino-esp32/blob/79f77afc98ca3c7b2ddc76fedba038f2385aa402/libraries/Update/src/Updater.cpp#L318


      
              memcpy(_buffer + _bufferLen, data + (len - left), left);
              _bufferLen += left;
              if(_bufferLen == remaining()){
                  if(!_writeBuffer()){
                      return len - left;
                  }
              }
              return len;
          }
          
          
size_t UpdateClass::writeStream(Stream &data) {
              size_t written = 0;
              size_t toRead = 0;
              if(hasError() || !isRunning())
                  return 0;
          
          
    if(!_verifyHeader(data.peek())) {
                  _reset();
                  return 0;
              }

github.com

espressif/arduino-esp32/blob/79f77afc98ca3c7b2ddc76fedba038f2385aa402/libraries/Update/src/Update.h#L108


      
          void md5(uint8_t * result){ return _md5.getBytes(result); }
          
          
//Helpers
          uint8_t getError(){ return _error; }
          void clearError(){ _error = UPDATE_ERROR_OK; }
          bool hasError(){ return _error != UPDATE_ERROR_OK; }
          bool isRunning(){ return _size > 0; }
          bool isFinished(){ return _progress == _size; }
          size_t size(){ return _size; }
          size_t progress(){ return _progress; }
          size_t remaining(){ return _size - _progress; }
          
          
/*
            Template to write from objects that expose
            available() and read(uint8_t*, size_t) methods
            faster than the writeStream method
            writes only what is available
          */
          template<typename T>
          size_t write(T &data){
            size_t written = 0;

thesmike · May 26, 2020, 1:29pm

Ah, ok, thank you! I am not that native C++ guy, but of course I should have looked into the sources by myself.

So if I understand correctly, Update.begin() also sets the total size of the update and so Update.writeStream() will automatically return when the total bytes received reaches the total size, right?

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OTA: Passing incoming serial stream to Update.writeStream()

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