LIN Sensor reading trouble

[kocokm]

Dear Reader

I am trying to read any kind of feedback from a LIN sensor. I am using an MCP2003B click shield with an Arduino mega as it allows you to communicate via hardware serial on tx1 and rx1. I send a break field, sync and id to the sensor as stated on it's datasheet every 200ms at 19200 baud as it needs. However, when I try to print the values, I simply receive the sync and ID I sent it? When i disconnect the sensor from power Serial.available() no longer runs and It return no response, very confusing I tested the Voltage of the LIN bus I read 12V (power supply). I believe this should be low when the LIN bus is communicating? Any help would be greatly appreciated.

[kocokm]

#define LIN_SERIAL Serial1 //tx1 rx1
#define REQUEST_INTERVAL 200 // 200ms
#define LIN_REQUEST_ID 0x27
#define LIN_FRAME_SIZE 8

unsigned long lastRequestTime =0; // Time tracking for response interval
uint8_t linResponse[LIN_FRAME_SIZE]; //array of size 8 buffer for linresponse

void sendLINHeader() {
//send break signal(13+ bits of low)

Serial.flush();
Serial.begin(12000);
Serial.write(0x0);
Serial.flush(); // send 0x00 at lower baud rate to give the break character
Serial.begin(19200);

Serial1.write(0x55);// sync byte
Serial1.write(0x0E);// ID

}

void setup() {

Serial.begin(115200);

Serial1.begin(19200); //specified baud

delay(1000);

digitalWrite(53,HIGH); // CS high to put mcp2003b in ready mode (datasheet)

}

void loop() {

unsigned long currentTime = millis();

if (currentTime - lastRequestTime >= 200) {
lastRequestTime = currentTime;

sendLINHeader(); //send header every 200ms

Serial.print("RAW LIN RESPONSE ");
int count =0;
while(Serial1.available()) {
uint8_t byteRead = Serial1.read();
if(byteRead < 0x10) Serial.print("0");
Serial.print(byteRead,HEX);
Serial.print(" ");
count ++;
}

if(count ==0) {
Serial.println(" No response");
}

else {
Serial.println();
}

}

}

[UKHeliBob]

Please follow the advice given in the link below when posting code, in particular the section entitled 'Posting code and common code problems'

Use code tags (the < CODE/ > icon above the compose window) to make it easier to read and copy for examination

https://forum.arduino.cc/t/how-to-get-the-best-out-of-this-forum

Please post your full sketch, using code tags when you do

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In my experience the easiest way to tidy up the code and add the code tags is as follows

Start by tidying up your code by using Tools/Auto Format in the IDE to make it easier to read. Then use Edit/Copy for Forum and paste what was copied in a new reply. Code tags will have been added to the code to make it easy to read in the forum thus making it easier to provide help.

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