Assistance assigning a changing input value to a "int" type name for "if" action

Projects Programming
1

Hi All.

I'm trying to build a can-bus to bluetooth adapter. The goal is to read the can-bus on my car, and when specific messages are received, perform a corresponding action.

To simplify -

I press a button on my steering wheel (I'll use track forward for example)

The can-bus shield reads the can-bus message for that action ("1D6 2 E000")

Arduino then tells the bluetooth adapter to send a hex command via software serial:

if(CANbus == "1D6 2 E000") // (button up) sends (track?) forward command then release
{

  • blueSmirf.write(0xFD);*
  • blueSmirf.write(0x03);*
  • blueSmirf.write(0x03);*
  • blueSmirf.write(0x100);*
  • blueSmirf.write(0x00);*
  • blueSmirf.write(0xFD);*
  • blueSmirf.write(0x03);*
  • blueSmirf.write(0x03);*
  • blueSmirf.write(0x00);*
  • blueSmirf.write(0x00);*
  • }*

My Android tablet then performs track forward.

I know all the write commands to perform the actions I need.

Where I'm stuck is reading the can-bus message, storing it as a value, and having the corresponding action performed if the value matches one of many "if" statements.

Here's my code so far:

#include <SPI.h>
#include <mcp_can.h>
#include <mcp_can_dfs.h>
#include <SoftwareSerial.h>

SoftwareSerial blueSmirf (10, 11);

void setup() 
{
Serial.begin(115200);
blueSmirf.begin(115200);
CAN.begin(CAN_500KBPS);                       // init can bus : baudrate = 500k
attachInterrupt(0, MCP2515_ISR, FALLING);     // start interrupt
}

void MCP2515_ISR()
{
    Flag_Recv = 1;
}
 
void loop()
{
    if(Flag_Recv)                           // check if get data
    {
      Flag_Recv = 0;                        // clear flag
      CAN.readMsgBuf(&len, buf);            // read data,  len: data length, buf: data buf
}
    
int CANbus = CAN.readMsgBuf;

void Action()
{
  if(CANbus == "1D6 2 E000") // (button up) sends (track?) forward command then release
  { 
    blueSmirf.write(0xFD);
    blueSmirf.write(0x03);
    blueSmirf.write(0x03);
    blueSmirf.write(0x100);
    blueSmirf.write(0x00);
    blueSmirf.write(0xFD);
    blueSmirf.write(0x03);
    blueSmirf.write(0x03);
    blueSmirf.write(0x00);
    blueSmirf.write(0x00);
  }
  
  if(CANbus == "1D6 2 D000") // (button down) sends (track?) back command then release
  {
    blueSmirf.write(0xFD);
    blueSmirf.write(0x03);
    blueSmirf.write(0x03);
    blueSmirf.write(0x200);
    blueSmirf.write(0x00);
    blueSmirf.write(0xFD);
    blueSmirf.write(0x03);
    blueSmirf.write(0x03);
    blueSmirf.write(0x00);
    blueSmirf.write(0x00);
  }
  
  if(CANbus == "1D6 2 C100") // (phone button) momentarily send play/pause command then release
  {
    blueSmirf.write(0xFD);
    blueSmirf.write(0x03);
    blueSmirf.write(0x03);
    blueSmirf.write(0x80);
    blueSmirf.write(0x00);
    blueSmirf.write(0xFD);
    blueSmirf.write(0x03);
    blueSmirf.write(0x03);
    blueSmirf.write(0x00);
    blueSmirf.write(0x00);
  }
}

I don't believe int CANbus = CAN.readMsgBuf; is the write way to do this, and it pukes on compile:

can_to_bt_test_1.ino: In function 'void setup()':
can_to_bt_test_1.ino:14:1: error: 'CAN' was not declared in this scope
can_to_bt_test_1.ino: In function 'void MCP2515_ISR()':
can_to_bt_test_1.ino:20:5: error: 'Flag_Recv' was not declared in this scope
can_to_bt_test_1.ino: In function 'void loop()':
can_to_bt_test_1.ino:25:8: error: 'Flag_Recv' was not declared in this scope
can_to_bt_test_1.ino:28:7: error: 'CAN' was not declared in this scope
can_to_bt_test_1.ino:28:23: error: 'len' was not declared in this scope
can_to_bt_test_1.ino:28:28: error: 'buf' was not declared in this scope
can_to_bt_test_1.ino:31:14: error: 'CAN' was not declared in this scope
can_to_bt_test_1.ino:34:1: error: a function-definition is not allowed here before '{' token
can_to_bt_test_1.ino:83:1: error: expected '}' at end of input
'CAN' was not declared in this scope

Any ideas on how to fix it?

2

and it pukes on compile:

Because your code gives it an upset stomach.

Where have you defined an instance called CAN? Nowhere is the wrong answer.

    Flag_Recv = 1;

You can't just make shit up as you go. You need to define ALL variables BEFORE you reference them.

void Action()

You can NOT define a function inside another function.

For someone with your current skill level, this project is too advanced.

3

You can not assign a string to an int.
You can put it into a string array. Look in the Reference
section for strings and arrays.
Your string looks to be 10 bytes long. An int can only
be packed with two bytes.
Also, Paul's last two observations.
Dwight