Can Shield v2 and Arduino Mega "Can Init Fail"

Projects Programming
1

Good morning,

I have an Arduino Mega 2560 (Genuine) and a Can Bus Shield V2 (Seed Studio), in order to read data from CAN Bus (non transmit).

I need to communicate between them via SPI and I did the following connections:

SCK - Arduino Mega pin 52 <-> CAN Shield pin D13
MISO - Arduino Mega pin 50 <-> CAN Shield pin D12
MOSI - Arduino Mega pin 51 <-> CAN Shield pin D11
CS - Arduino Mega pin 9 <-> CAN Shield pin D9

Power supply to CAN Bush Shield is from pin 5V of Arduino Mega to 5V pin of CAN Shield.
If not, (connecting Vin pins the CAN communication doesn't work).

Using library from website CAN-BUS Shield V2.0 - Seeed Wiki
I wrote the following code:

#include <SPI.h>
#include "mcp2515_can.h"

const int SPI_CS_PIN = 9;
mcp2515_can CAN(SPI_CS_PIN); // Set CS pin for CAN shield

void setup(void) {    

  Serial.begin(9600); // debug serial

    while (CAN_OK != CAN.begin(CAN_500KBPS)) {   // can bus : baudrate = 500k
        Serial.println(F("CAN init fail, retry..."));
        delay(100);
    }
    Serial.println(F("CAN init ok!"));

}

void loop(void) {  

 Serial.println(F("Looping"));

}

CAN Init Fail error occurs with CAN bus connected and trasmitting and without CAN connected.

I tried also Examples CODE and I also tried to change pin 9 to others but nothing.

I used in the past the same can bus shild with an arduino nano and it worked. Now I have only the Mega board.
I'm also afraid that the Can Shield is damaged but it is strange because is was in a box during inutilization period.

Do you have suggestion based on your experience?

Thanks to all!

2

u mean: Changing CAN shield Pin 9, or Mega pin 9??

did you try:
CS - Arduino Mega pin 9 <-> CAN Shield pin D10?

3

Good morning sherzaad,

thanks for your reply.

I tried both (4 occurrences):
CS - Arduino Mega pin 9 <-> CAN Shield pin D9
CS - Arduino Mega pin 9 <-> CAN Shield pin D10
CS - Arduino Mega pin 10 <-> CAN Shield pin D9
CS - Arduino Mega pin 10 <-> CAN Shield pin D10

Theoretically the shield has as default CS pin the D9, in order to change it is necessary an hardware trick (with dedicated pads in the bottom side of the board) and I leaved the default D9 pin.

One other question, if CAN bus isn't connected, the initialization will be OK or will returns error?
I don't remember the result of the initialization process without CAN BUS connected.

Thanks a lot!!

4

if setup is OK and no CAN bus is connected, you should still get and OK for the initialisation phase.

5

Hi,
This may help;

PINMAP
PINMAP1647×1293 299 KB

Tom.. :smiley: :+1: :coffee: :australia:

6

Thanks but the connections are ok.
I also changed the can shield with another one working from a friend of mine.
The problem is the same.
Pinout connection are correct based on PINOUT schematics for Mega and Can shield v2.

The Chip is the MCP2515

Someone has other ideas?

Thanks a lot!

7

I've found two things,
First:
is mandatory for MCP2515 declare also the INT pin (2), if not the communication doesn't works.

Second:
if the CAN shield board is not mounted on Arduino board, connecting only:
SCK, MISO, MOSI, CS, +5V, GND, Interrupt (pin2), the board doesn't work, interrupt dowsn't work and CAN doesn't init.

Mounting the CAN Shield on the Arduino board it works only if both boards are powered by USB OR via 5V pin, NOT Vin pin (also using +5V as power supply).

It's very strange for me.

Do you have other experiences?

8

those would be the minimum wiring required to make this sheild work, nothing new there! :wink:

9

Hi,

Vin needs at least 7V to function, it is the input to the onboard 5V regulator, it is a linear reg and so needs about 2V or more higher input than 5V output.

If you look at the diagram I posted in post #5, it shows the free pins and the pins that need connection, there are more than just the pins you have listed.
Among them is D2 which is the interrupt pin.

Tom... :smiley: :+1: :coffee: :australia:

10

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.