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SERIAL CAN BUS MODULE

Introduction


The Serial CAN BUS provide your Arduino or others MCU with the capability to communication to CAN Bus, such as hacking your vehicle. CAN Bus is a common industrial bus because of its long travel distance, medium communication speed and high reliability.

This Serial CAN Bus module is based on MCP2551 and MCP2515, which can provide speed up to 1Mb/s.

Note

Because the Arduino library provided by this module uses a soft serial port, it is only suitable for AVR series Arduino, such as Arduino UNO, Arduino Mega, Arduino Leonardo, etc. If you use other non-AVR series Arduino, you may need to modify the library to use it.

Note

The default masks and filters is for standard can frame, if you need to receive a ext can frame, please set the mask and filt first.

Version Track

Version VCC IO Level MCU Others Change
V1.0 5V 5V Atmega328P NO
V1.1 5V 5V/3.3V Atmega328P Add a pads for the 3.3V IO
V1.2 5V 5V/3.3V Atmega168PA Change the MCU to Atmega168PA
V1.3 5V/3.3V 5V/3.3V Atmega168PA Support 3.3V VCC

CAN BUS PRODUCTS LIST OF LONGAN-LABS

We have made a lot of can bus products, you can get more information through the following list, so as to choose a product suitable for you.

PRODUCT NAME LINK PRICE MCU CHIP PROTOCOL
Serial CAN Bus Module LINK $19.9 ATMEGA168PA MCP2515 CAN2.0
I2C CAN Bus Module LINK $19.9 ATMEGA168PA MCP2515 CAN2.0
OBD-II Serial CAN Bus Dev Kit LINK $20.9 ATMEGA168PA MCP2515 CAN2.0
OBD-II CAN Bus GPS Dev Kit LINK $29.9 ATMEGA32U4 MCP2515 CAN2.0
OBD-II CAN Bus Basic Dev Kit LINK $24.9 ATMEGA32U4 MCP2515 CAN2.0
CAN-FD Shield LINK $12.9 NO MCU MCP2517FD CAN-FD
CAN Bus Shield LINK $5.9 NO MCU MCP2515 CAN2.0
CANBed LINK $24.9 ATMEGA32U4 MCP2515 CAN2.0
CANBed-FD LINK $19.9 ATMEGA32U4 MCP2517FD CAN-FD
CANBed M0 LINK $24.9 ATSAMD21 MCP2515 CAN2.0
CANBed M4 LINK $19.9 ATSAME51 - CAN-FD
OBD-II RF Dev Kit LINK $19.9 ATmega168PA MCP2515 CAN2.0

Partlist


Features


  • Uart to CAN Bus
  • Work with Arduino/BeagleBone board/Pi or any MCU that integrated with UART.
  • AT command
  • Up to 115200 Uart baud rate (default 9600)
  • Up to 1Mb/s CAN Bus baud rate (default 500k)
  • TX and RX led indicator
  • 4pin HY connector
  • 3.3 / 5V working voltage
  • Easy-to-use Arduino library
  • Small size: 20x40 mm

Hardware Overview


  1. 4 pin 2.0mm Grove Connector
  2. Power and status led indicator
  3. Send and Recv led indicator
  4. 3.5mm terminal to connect to CAN Bus (CAN_H & CAN_L)
  5. 120Ω registor.

120 Terminal resistor

If you need the 120Ω terminal resistor, you need a soldering iron, as shown below:

Work at 3.3V


The module is working at 5V most of time. If you want it to work at 3.3V IO, please try:

V1.3 Version

V1.3 work well at 3.3V IO and VCC.

V1.1 and V1.2 Verstion

There's a jumper on the back side, please connect the pads together with a soldering iron. And VCC must connect to 5V.

V1.0 Version

Please try as below, and please note that VCC till need to connect to 5V.

AT Command


You can achieve the complete function of this Serial CAN Bus module with only a few AT command.

CMD Description
+++ Switch from Normal mode to Config mode
AT+S=[value] Set serial baud rate
AT+C=[value] Set CAN Bus baud rate
AT+M=[N][EXT][value] Set mask
AT+F=[N][EXT][value] Set filter
AT+Q Switch to Normal Mode

Note

All of the cmd should end with '\n' except +++

Set the Baud Rate of UART


You can set the baud rate of UART of the module with this command. There're 5 rates available, up to 115200 b/s.

AT+S=[value]
value 0 1 2 3 4
baud rate(b/s) 9600 19200 38400 57600 115200

Note

Default is 9600

Eg: Set serial baud rate to 57600

AT+S=3

Respose

OK or ERROR

Note

If you are using the SoftwareSerial of Arduino, please don't set the baud rate to 115200.

Set CAN Bus Baudrate


You can use this command to set the rate of CAN Bus, there's 18 rates available. Normally, if you want to hack your vehicle, 500k is the right one.

AT+C=[value]
value 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
rate(kb/s) 5 10 20 25 31.2 33 40 50 80 83.3 95 100 125 200 250 500 666 1000

Tip

Default is 500K

Eg: Set CAN BUS baud rate to 50K

AT+C=08

Respose

OK or ERROR

Set Mask


There're 2 Mask for the module, Mask0 and Mask1.

AT+M=[N][EXT][value]

N:

  • 0: Mask0
  • 1: Mask1

EXT:

  • 0: Standard Frame
  • 1: Extended Frame

value:

Neeed 8 bit of character, hexadecimal.

Eg: Set Mask1 to 0x3DF, standard frame:

AT+M=[1][0][000003DF]

Respose

OK or ERROR

Set Filt


There're 6 Mask for the module, Filt0 ~ Filt5

AT+F=[N][EXT][value]

N:

N 0 1 2 3 4 5
Filt Filt0 Filt1 Filt2 Filt3 Filt4 Filt5

EXT:

  • 0: Standard Frame
  • 1: Extended Frame

value:

Neeed 8 bit of character, hexadecimal.

Eg: Set Filt3 to 0x2C, standard frame:

AT+F=[1][0][0000002C]

Respose

OK or ERROR

Working Mode


When the module working on Working mode (default mode), you can send and recevie data from CAN Bus.

Send

You should send 14 byte of data per frame. Defined as below,

bit 0 1 2 3 4 5 6 7 8 9 10 11 12 13
define ID3 ID2 ID1 ID0 EXT RTR DTA0 DTA1 DTA2 DTA3 DTA4 DTA5 DTA6 DTA7
  • ID0~ID3: CAN ID
  • EXT: 0 for standard frame, 1 for extended frame
  • RTR: 0 for standard frame, 1 for remote frame
  • DTA0~DTA7: 8 byte of data

Eg.

Send {1, 2, 3, 4, 5, 6, 7, 8} to ID:0x3DC, Standard frame:

{0, 0, 3, 0xDC, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8}

Recv

You will get 12 byte of data per frame. Defined as below,

bit 0 1 2 3 4 5 6 7 8 9 10 11
define ID3 ID2 ID1 ID0 DTA0 DTA1 DTA2 DTA3 DTA4 DTA5 DTA6 DTA7
  • ID0~ID3: CAN ID
  • DTA0~DTA7: 8 byte of data

Work with Arduino


120Ω Terminal Resistor

As there're only 2 serial can bus device, it need the 120Ω resistor, there's a P1 on the back side, please solder P1 to get the 120Ω resistor, as shown below,

Hardware Connection

There are 4 pins on the board, they are:

Pin Name Function Color
TX TX of UART Yellow
RX RX of UART White
5V VCC, connect to 5V (V1.0/V1.1/V1.2/V1.3) or 3.3V(only V1.3 or after) Red
GND Ground Black

If you got a Base Shield from Seeedstudio, the connection is easy, like below,

If there's no Base Shield for you, you need some dupont cable, and connect TX/RX to the IO of your Arduino, here we connect TX/RX to D2/D3:

Note

Not all pins on the Mega and Mega 2560 support change interrupts, so only the following can be used for RX: 10, 11, 12, 13, 14, 15, 50, 51, 52, 53, A8 (62), A9 (63), A10 (64), A11 (65), A12 (66), A13 (67), A14 (68), A15 (69).

Software

We provide an library for Aruino Software Serial.

Please download it at Github

There're many examples for the library, which is consist of,

  • send - How to send a frame to CAN Bus
  • recv - How to recv a frame from CAN Bus
  • debug - debug mode, you can send a cmd to the module
  • set_can_baudrate - set can bus baudrate
  • set_mask_filt - set mask and filt of the module

Test the board

Here we make an example to show you how the board work with CAN Bus.

The connection like below, here we use Seeeduino + Serial CAN bus module as the receiver, and a USB2Uart module + Serial CAN bus module as sender.

If you send the command of sending frame to the USB2Uart module, open the Arduino serial monitor, you will get data from CAN Bus.

Working Standalone


For V1.2 and after, you can program the on-board MCU (Atmega168PA) with Arduino IDE.

First, you need a USB to Serial board, something like the Programmer Card

Here we will take Programmer Card as an example:

Then, we need to setup your Arduino IDE.

Start the Arduino IDE.

Copy and paste the link below into the Additional Boards Manager URLs option in the Arduino IDE preferences (File > Preferences).

https://raw.githubusercontent.com/Longan-Labs/Longan-Board/master/package_longan_boards_index.json

The Longan AVR boards supplied package includes supports for Longan Card, Carduino 328, Carduino 32U4.

Once done, click OK button to save the new preference settings.

Now open the Boards Manager by navigating to the Tools -> Board menu.

Select All from the Type drop-down menu. Then type longan in the top search bar. While typing, you will see the Longan AVR package.

Click on the Longan AVR by Longan Labs and then click on Install button.

Once installed, close the Boards Manager window.

Then you can find Serial CAN Bus Module in the board list.

FAQ

The RX and TX leds light up instead of blinking

  • Please check the baudrate of CAN Bus
  • If the serial can bus module is in the end, the 120Ω terminal resistor is needed, please soder P1 on the back side of PCBA

Don't work with Arduino Mega

Not all pins on the Mega and Mega 2560 support change interrupts, so only the following can be used for RX: 10, 11, 12, 13, 14, 15, 50, 51, 52, 53, A8 (62), A9 (63), A10 (64), A11 (65), A12 (66), A13 (67), A14 (68), A15 (69).

How to find the tech support

Please contact support@longan-labs.cc for technical support. Our technical support engineer will usually reply you within 24 hours on working days. In order to get faster support, we hope that when you send us an email, you need to include at least the following content,

  • When and how to buy the product
  • Product version information
  • Take a high-definition picture of the product you use, including the connection
  • Describe in detail the problem you encountered and what kind of help you would like to get

Schematic Online Viewer

Reference