Uart receiveing issues

Using Arduino Networking, Protocols, and Devices
1

Hello! I have a project in which I have to use UART connection between Arduinos. What i have on 1 Arduino, is 4 sensors which values are stored in an array, and a value of 0 or 1 stored in respective array if the sensor is activated or not.
I'm trying to send the 0 or 1 for each sensor at the same time to the other Arduino. I went about it by doing Serial.write(array,size). the "array" inside is byte var[4];. The com port for writing shows correctly which is activated e.g 0100 --> Sensor 2 is activated. I send the variable in 0x30 for 0 and 0x31 for 1.
The issue is, the receiving side does get the 1011, but then loads of random numbers for a while, until the 0100 shows up again. I can't figure out why. The way i went about reading the value: Serial.readBytes(data,4) Where data is also a Byte data[4]; and then serial.print(data[0]-48)... etc until [3].

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2

Are you sending a sentence or just the data without a sentence structure?

Say your sentence looked like this "<#,1,0,1,1,0>", with a "<" that represents the beginning of the dat stream and the ">" as the end.

If your receiver looks for a < before it starts recording data and a > to end its data recording, your receiver can synchronize its data receptions with the sender.

void fReceiveSerial_LIDAR( void * parameters  )
{
  bool BeginSentence = false;
  char OneChar;
  char *str;
  str = (char *)ps_calloc(300, sizeof(char) ); // put str buffer into PSRAM
  for ( ;; )
  {
    EventBits_t xbit = xEventGroupWaitBits (eg, evtReceiveSerial_LIDAR, pdTRUE, pdTRUE, portMAX_DELAY);
    if ( LIDARSerial.available() >= 1 )
    {
      while ( LIDARSerial.available() )
      {
        OneChar = LIDARSerial.read();
        if ( BeginSentence )
        {
          if ( OneChar == '>')
          {
            if ( xSemaphoreTake( sema_ParseLIDAR_ReceivedSerial, xSemaphoreTicksToWait10 ) == pdTRUE )
            {
               xQueueOverwrite( xQ_LIDAR_Display_INFO, ( void * ) &str );
              xEventGroupSetBits( eg, evtParseLIDAR_ReceivedSerial );
              //
            }
            BeginSentence = false;
            break;
          }
          strncat( str, &OneChar, 1 );
        }
        else
        {
          if ( OneChar == '<' )
          {
            strcpy( str, ""); // clear string buffer
            BeginSentence = true; // found beginning of sentence
          }
        }
      } //  while ( LIDARSerial.available() )
    } //if ( LIDARSerial.available() >= 1 )
    xSemaphoreGive( sema_ReceiveSerial_LIDAR );
    //        log_i( "fReceiveSerial_LIDAR " );
    //        log_i(uxTaskGetStackHighWaterMark( NULL ));
  }
  free(str);
  vTaskDelete( NULL );
} //void fParseSerial( void * parameters  )

The example code shows the principle I have been using from Uno's to ESP32's to receive serial data; ignore the ESP32 code.

3

Can you please post the send and receive code which gives you the output you posted.

An excellent tutorial is Robin2's Serial Input Basics.

4

If you want to beta test my code and schematics for sending between two Arduinos, (UNO, Mega2650, ESP8266, ESP8266-01, ESP32, PC(python) ), drop a MP with your email and the two boards you are using.
The code sends text lines, auto connects and re-connects, works with half-duplex software like the UNO/Mega Software Serial, includes a checksum and is very tolerant of processing delays on either side.

5

Does the ESP32 code directly use the ESP32 I2C API or does the code use the Arduino Core API for ESP32 I2C communications?

6

Here is a draft of the software and board circuits I have so far
https://www.forward.com.au/pfod/ArduinoProgramming/SoftwareSolutions/ComsPair.html

7

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