OneWire

[coderatchance]

Hello all,

trying to communicate between two tinys via oneWire, hw wise I am following the maxim, dallas, microchip (https://www.microchip.com/content/dam/mchp/documents/OTH/ApplicationNotes/ApplicationNotes/AN2658-USART-In-One-Wire-Mode-00002658C.pdf) etc.

However, I am setting up the software via the megaTinyCore. Trying to use the Serial.read and write.
When connecting the same tinys via the RS485 and transceiver in the past the following code worked,
wondering why it would not in this case? Indeed, this time I do not need the "digital pin" as required by the transceivers ...

Started with the test, if it is works, namely in one direction going from one tiny to the other.
Below is the code, however, it does not work wondering what I am doing wrong sw wise.
I guess 2400 Bauds is not too fast for the oneWire that can handle up to 16.3kbps ...

Any input is much appreciated!

Best.

1. tiny is 3216 and is suppose to send:

/**
  1.
  
  ONE_WIRE TESTING at tiny3216
  speaking, writing part
  
**/

byte myLed = 0;

void setup() {

  //UART0  serial -> one-wire setup
  Serial.swap(0);
  Serial.begin(2400);


  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB
  }

  //turn off hte led
  pinMode(myLed, OUTPUT);
  analogWrite(myLed, 0);

}

void loop() {
  analogWrite(myLed, 255);
  Serial.write(45); // send a byte with the value 45
  Serial.flush ();
}

2. tiny is 1626 and is suppose to read and print out on the screen:

int incomingByte = 0; // for incoming serial data
byte myByte = 1; // for incoming serial data
byte myLed = 0;

void setup() {
  //UART0  serial -> screen
  Serial.swap(0);
  Serial.begin(2400);

  //UART1 one-wire
  Serial1.swap(2);
  Serial1.begin(2400);

  while (!Serial && !Serial1) {
    ; // wait for serial port to connect. Needed for native USB
  }

  //serials ready
  Serial.println("Serial and Serial1 OK");
  delay(1000);
  //turn off hte led
  pinMode(myLed, OUTPUT);
  analogWrite(myLed, 0);
}

void loop() {
  Serial.println("listening Serial1 ...");
  analogWrite(myLed, 255);
  //UART1, Serial1 is listening
  // reply only when you receive data:
  if (Serial1.available() > 0) {
    // read the incoming byte:
    incomingByte = Serial1.read();
    // say what you got:
    Serial.print("I received: ");
    Serial.println(incomingByte, DEC);
  }
}

[hmeijdam]

While I have never used OneWire myself on these parts, I don't see you applying a modifier to activate OneWire (SERIAL_HALF_DUPLEX) in the trasmitting sketch.

[coderatchance]

Cheers! I have used this Serial.begin(2400, SERIAL_HALF_DUPLEX); for the uart I am using to send and receive.
I am sending with the following:

 void loop() {
  analogWrite(myLed, 255);
 
  Serial.write(12); // send a byte with the value 45

  Serial.flush ();

}

while I am receiving with the following:

void loop() {

  analogWrite(myLed, 255);

  //UART1, Serial1 is listening
  // reply only when you receive data:
  if (true) {
    // read the incoming byte:
    incomingByte = Serial1.read();
    // say what you got:
    Serial.print("I received: ");
    Serial.println(incomingByte, DEC);
  }
} 

As you can see I have removed the "if (Serial1.available() > 0) { ... " because somehow I cannot get serial output or input correct.
For example, I am reading the

I received: -1
I received: -1
I received: -1

or HEX

I received: FFFFFFFF
I received: FFFFFFFF
I received: FFFFFFFF

Not sure what I am doing wrong.
I guess the HALF_DUPLEX should as well be enabled in the receiving side, like in this way, is it correct Serial1.begin(2400,SERIAL_HALF_DUPLEX); or should the SERIAL_HALF_DUPLEX be removed ? Anyway, what would be the minimum "test code" to check that the connection works?
And another thing, when the "Serial.write" is changed to different value, it does not affect the serial output on the receiving/listening side, apparently, comm. is not working...

Best.