Sending INT over CAN_SHIELD not Possible

Projects Programming
1

hey guys,

i have the problem since two days.

First i show you what i got:

void UpdatePointer(void) {
  if (initComplete == 9) {
    digitalWrite(ncs, LOW);
    xydat[0] = (int)adns_read_reg(REG_Delta_X_L);
    xydat[1] = (int)adns_read_reg(REG_Delta_Y_L);
    digitalWrite(ncs, HIGH);
    //sendMsg(0x01, 1, 1, 1, xydat[0]);
    //const int SPI_CS_PIN = 5;
    //MCP_CAN CAN(SPI_CS_PIN);        // Set CS pin
    //byte sndStat = CAN.sendMsgBuf(0x1CFF01F2, 1, 2, xydat[0]);
    //CAN.sendMsgBuf(0x01, 0, 2, xydat[0]);
    Serial.println(xydat[0]);
    Serial.println(xydat[1]);
    movementflag = 1;
  }
}

you can see, how much i change something to get an solution.
You should also know, the programm works with the serial.println fine.

libary is included

Any Suggestions?

mcp_can.h (8.54 KB)

mcp_can_dfs.h (13.4 KB)

2

What do you receive from the send line? Is it only one byte of the integer? Have you tried to send the two bytes individually and then reconstitute them?

3 
        xydat[0] = (int)adns_read_reg(REG_Delta_X_L);
        xydat[1] = (int)adns_read_reg(REG_Delta_Y_L);

since you're casting the adns_read_reg() to an int, suggests that xydat is at least an array of integers.

presumably you need to pass sendMsgBuf() a pointer to the data and the size should be the total number of bytes, at least 4, 2 bytes/integer

        byte sndStat = CAN.sendMsgBuf(0x1CFF01F2, 1, sizeof(xydat), & xydat[0]);
4

adwsystems:
What do you receive from the send line? Is it only one byte of the integer? Have you tried to send the two bytes individually and then reconstitute them?

I can't get it working. I try everything. If it will be compiled.. I'm sure I can received them with a professional measurement equipment. That is Not the problem.

Furthermore I get a cheaper Adns sensor to work and send it also before over can.

5

nitecmusic:
I can't get it working.

What is not working? We can only help with specific issues and details. Lots of information has been provided. What have you tried? How did it fail?

6

adwsystems:
What is not working? We can only help with specific issues and details. Lots of information has been provided. What have you tried? How did it fail?

Sry adwsystems,

i try this now

byte sndStat = CAN.sendMsgBuf(0x01, 1, sizeof(xydat), & xydat[0]);

and i get

no matching function for call to 'MCP_CAN::sendMsgBuf(int, int, unsigned int, volatile int*)'

7

do you need to cast the pointer to a byte ?

byte sndStat = CAN.sendMsgBuf(0x01, 1, sizeof(xydat), (uint8_t*)& xydat[0]);
8

Here is how I break down a int into a byte to send over CAN

 // prep item for sending over CAN buss
        if (!PassTwo)
        {
          rx_frame.FIR.B.FF = CAN_frame_std;
          rx_frame.MsgID = 1;
          rx_frame.FIR.B.DLC = 8;
          rx_frame.data.u8[0] = *item & 0xFF;
          rx_frame.data.u8[1] = (*item >> 8) & 0xFF;
          rx_frame.data.u8[2] = (*item >> 16) & 0xFF;
          rx_frame.data.u8[3] = (*item >> 24) & 0xFF;
          PassTwo = true;
        } else {
          rx_frame.data.u8[4] = *item & 0xFF;;
          rx_frame.data.u8[5] = (*item >> 8) & 0xFF;
          rx_frame.data.u8[6] = (*item >> 16) & 0xFF;
          rx_frame.data.u8[7] = (*item >> 24) & 0xFF;
          ESP32Can.CANWriteFrame(&rx_frame); // send items over CAN buss
          PassTwo = false;
        }
9

there no need ....

just pass a pointer to your data (e.g. long) case as a byte pointer (i.e. (byte *) & longVar and specify the size of the data in bytes (e.g. sizeof(longVar) or sizeof(longVarArray))