Simulink/Arduino: serial receive byte stream

Hello,

I am using Simulink to receive serial data via Arduino, which is receiving three bytes (unit8) of data from a 2nd microcontroller. The 3-byte packet includes a startChar and 2 bytes of data, illustrated below.

Occasionally, if I reset the transmitting microcontroller, I notice the receiving bytes get jumbled and the starChar (36) is positioned either in the 2nd or 3rd index of the byte array. As a result this will completely ruin the rest of my model. To fix this I need to keep resetting the tranmistting controller.

What can I do to prevent this from happening?

[Walter Roberson]

is the next group of bytes sent correctly or have you lost synchronization?

[Daniel Gelman]

I think you may be on to something. It may be a problem with the transmitting bytes.

The transmitting microcontroller is another Arduino, which is transmitting the three bytes every 20 Hz in a timer, shown below.

void myHandler() {
  myBytes[0] = myInt >> 8;
  myBytes[1] = myInt;
  Serial1.write('$');
  Serial1.write(myBytes[0]);
  Serial1.write(myBytes[1]);
}

However, if I reset the controller at the right time, we may be a jumble on the transmitting bytes. Shown below are the bytes sent to the Simulink Arduino. If I reset it at just the right time, this happens:

$⸮
$⸮
$⸮
$⸮
$⸮$⸮
$⸮
$⸮
$⸮
$⸮
$⸮

I need to add some delay or trigger between Arduinos to prevent this.

[Walter Roberson]

ir looks to me as if $ is not necessarily invalid as a packet? That in theory you could get even $$$ as a packet?

[Amrtanshu Raj]

Is your transmitting microcontroller also a arduino? What is the method of resetting the transmitting microcontroller?

[Daniel Gelman]

Amrtanshu, yes the transmitting microcontroller is an Arduino.

Answer 1

[Amrtanshu Raj]

Hi,

As far as I understand your problem, you are randomly resetting the transmitting microcontroller which is causing the input data stream to be jumbled up.

A possible work around to this problem can be achieved by adding the subsystem in the attached file between the serial port and the display.

Hope this helps!