CC2500: Communication between MSP430F5529 and Arduino Mega2560 using CC2500 - Synchronization Problem

Hello,

Can you please provide a block diagram of your system?

If I understand correctly, you have two systems, each with a controller + CC2500 like so:

1. MSP + CC2500 (for simplification, I'll call this MSP)
2. Arduino + CC2500 (for simplification, I'll call this Ard)

I would recommend that you test delays when transitioning from RX to TX, and also to ensure the RX time of the other device remains on for a bit longer.
For example, a sequence could look like this:

1. MSP switches from TX to RX at time t_rxStart, and stays this way for t_rxStay
2. Ard switches from RX to TX at time t_txStart, where t_rxStart + t_txDelta < t_txStart < t_rxStart + t_rxStay

I'd recommend adding GPIO toggles on both MSP and Ard to indicate where each TX and RX is starting (i.e. 2 GPIOs on each controller, one for TX active and one for RX active).

Thanks,
Toby

Hello Toby,

I have updated the post with the block diagram to make it more visually understandable!

In follow up to your suggestion i have a question, right now the distance between the modules is short but if the distance would increase these delays would most likely have to be adjusted right?

Im gonna try your suggestion, going to try to find out when the TX and RX modes start and go from there.

I'll get back at you, thank you very much for your help and time!

Hello Toby i am now able of receiving and sending between both microcontrollers but for some reason the msp gets stuck in receiver and cant receive anymore and i need to reset the arduino for it to start receiving again any clues?

Here is the codes updated:

Arduino

void loop() 
{
  delay(500);
  
  digitalWrite(5, HIGH);

  digitalWrite(4, HIGH);
  sendPacketINT(buffer_tx, 5);

  attachInterrupt(2, wakeUp, FALLING);

  LowPower.powerDown(SLEEP_FOREVER, ADC_OFF, BOD_OFF); 
  detachInterrupt(2);

  digitalWrite(4, LOW);

  SendStrobe(CC2500_SIDLE);
  SendStrobe(CC2500_SFTX);
  

  // RX
  SendStrobe(CC2500_SRX);
  digitalWrite(5, LOW);

  attachInterrupt(2, wakeUp, FALLING);

  LowPower.powerDown(SLEEP_FOREVER, ADC_OFF, BOD_OFF); 
  detachInterrupt(2);

  while(digitalRead(GDO0));

  listenForPacket(buffer_rx, 5);

  if (buffer_rx[4] == length)
  {
    digitalWrite(4, HIGH);
  }
  
  SendStrobe(CC2500_SFRX);
  delay(2000); // consegui 5 mensagens seguidas
}

  while (1)
  {
    // LER
    P2IFG &= ~BIT0;
    P2IE |= BIT0;
    
    sendStrobe(CC2500_SRX);
    __delay_cycles(1000);
    P1OUT &= ~BIT5;

    __bis_SR_register(GIE + LPM0_bits);

    P1OUT |= BIT5;

    for (int i = 0; i < 5; i++)
    {
      buffer_rx[i] = CC2500_read_register(CC2500_RXFIFO);
    }

    if (length == buffer_rx[4])
    {
      P1OUT |= BIT0;
      received = 1;
    }

    sendStrobe(CC2500_SIDLE);

    // Flush RX FIFO
    sendStrobe(CC2500_SFRX);
    
    for (int i = 0; i < 5; i++)
    {
      write(*(point_tx + i),CC2500_TXFIFO);
    }
    
    __delay_cycles(500000); // 500 ms
    // Transmitter mode
    sendStrobe(CC2500_STX);
    P1OUT &= ~BIT5;

    // reativar interrupt gdo e escrever tudo no TXFIFO
    P2IFG &= ~BIT0;
    P2IE |= BIT0;

    __bis_SR_register(GIE + LPM0_bits);

    // go back to rx mode and flush TX FIFO

    sendStrobe(CC2500_SIDLE);

    sendStrobe(CC2500_SFTX);
    __delay_cycles(1000);

    P1OUT &= ~BIT0;

Hello José,

Glad to hear things are progressing on your system! And thanks for sharing the block diagram.

For the new issue you observe, is it happening on known intervals? E.g. Does it always happen after X packets? or X time?

José Rita said:

the msp gets stuck in receiver and cant receive anymore and i need to reset the arduino for it to start receiving again

This is a good clue here. It seems what could be happening, is that MSP is stuck in receive because it started that particular RX not in time to receive the Ard TX. So then, when you reset the Ard TX, the MSP starts receiving packet again, since the MSP is now for sure in RX in time to receive the Ard TX.

I'd recommend playing around with the timing intervals, since there could be some additional timing variation which needs to be accounted for.

José Rita said:

In follow up to your suggestion i have a question, right now the distance between the modules is short but if the distance would increase these delays would most likely have to be adjusted right?

Yes, this is good intuition. The distance typically has impact on the timings due to reduced TX power (inverse square). More distance also introduces more potential sources of noise, which impacts over-the-air signals. Generally it's recommended to do range testing to verify working distance.

Thanks,
Toby