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¶

4 pin 2.0mm Grove Connector
Power and status led indicator
Send and Recv led indicator
3.5mm terminal to connect to CAN Bus (CAN_H & CAN_L)
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	4
baud rate(b/s)	9600	19200	38400	115200

Note

Default is 9600

Eg: Set serial baud rate to 115200

AT+S=4

Note

Please DON'T send AT+S=3 to the board, otherwise it may become brick.

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.

Get data from a Vehicle¶

We can use Serial CAN Bus Module to get data from a vehicle, we take the vehicle speed for an example here.

You can use our products to read data from cars. Here we provide a simple example by which you can read the speed and revs from a car. This is the OBD-based PIDs protocol. Regarding the deeper technology of OBD, we can't provide support at present. You may need to have some understanding of the car's protocol. After all, we are more of a hardware supplier.

The interface of OBD is as follows,

There're 4 pins we need to connect.

OBD Pin	CANBed PIN
6. CAN(J-2234) High	CANH
14. CAN(J-2234) Low	CANL

You can also use our OBD Connector, which is very convenient to connect to OBD.

Upload the following code to the development board, then open the serial monitor, you get the speed from the car now.

#include <Serial_CAN_Module.h>
#include <SoftwareSerial.h>

#define STANDARD_CAN_11BIT      1       // That depands on your car. some 1 some 0. 

Serial_CAN can;

#define can_tx  2           // tx of serial can module connect to D2
#define can_rx  3           // rx of serial can module connect to D3

#define PID_ENGIN_PRM       0x0C
#define PID_VEHICLE_SPEED   0x0D
#define PID_COOLANT_TEMP    0x05

#if STANDARD_CAN_11BIT
#define CAN_ID_PID          0x7DF
#else
#define CAN_ID_PID          0x18db33f1
#endif

#if STANDARD_CAN_11BIT
unsigned long mask[4] = 
{
    0, 0x7FC,                // ext, maks 0
    0, 0x7FC,                // ext, mask 1
};

unsigned long filt[12] = 
{
    0, 0x7E8,                // ext, filt 0
    0, 0x7E8,                // ext, filt 1
    0, 0x7E8,                // ext, filt 2
    0, 0x7E8,                // ext, filt 3
    0, 0x7E8,                // ext, filt 4
    0, 0x7E8,                // ext, filt 5
};

#else
unsigned long mask[4] =
{
    1, 0x1fffffff,               // ext, maks 0
    1, 0x1fffffff,
};

unsigned long filt[12] =
{
    1, 0x18DAF110,                // ext, filt
    1, 0x18DAF110,                // ext, filt 1
    1, 0x18DAF110,                // ext, filt 2
    1, 0x18DAF110,                // ext, filt 3
    1, 0x18DAF110,                // ext, filt 4
    1, 0x18DAF110,                // ext, filt 5
};
#endif

void set_mask_filt()
{
    /*
     * set mask, set both the mask to 0x3ff
     */

    if(can.setMask(mask))
    {
        Serial.println("set mask ok");
    }
    else
    {
        Serial.println("set mask fail");
    }

    /*
     * set filter, we can receive id from 0x04 ~ 0x09
     */
    if(can.setFilt(filt))
    {
        Serial.println("set filt ok");
    }
    else 
    {
        Serial.println("set filt fail");
    }
}

void sendPid(unsigned char __pid) {
    unsigned char tmp[8] = {0x02, 0x01, __pid, 0, 0, 0, 0, 0};

#if STANDARD_CAN_11BIT
    can.send(CAN_ID_PID, 0, 0, 8, tmp);   // SEND TO ID:0X55
#else
    can.send(CAN_ID_PID, 1, 0, 8, tmp);   // SEND TO ID:0X55
#endif
}

bool getSpeed(int *s)
{
    sendPid(PID_VEHICLE_SPEED);
    unsigned long __timeout = millis();

    while(millis()-__timeout < 1000)      // 1s time out
    {
        unsigned long id  = 0;
        unsigned char buf[8];

        if (can.recv(&id, buf)) {                // check if get data

            if(buf[1] == 0x41)
            {
                *s = buf[3];
                return 1;
            }
        }
    }

    return 0;
}

void setup() {
    Serial.begin(115200);
    while(!Serial);

    can.begin(can_tx, can_rx, 9600);      // tx, rx

    // set baudrate of CAN Bus to 500Kb/s
    if(can.canRate(CAN_RATE_500))
    {
        Serial.println("set can rate ok");
    }
    else
    {
        Serial.println("set can rate fail");
    }

    set_mask_filt();

    Serial.println("begin");
}

void loop() {

    int __speed = 0;
    int ret = getSpeed(&__speed);
    if(ret)
    {
        Serial.print("Vehicle Speed: ");
        Serial.print(__speed);
        Serial.println(" kmh");
    }
    delay(500);
}

// END FILE

If you want to get other data by PIDs, you can refer to the above example, and refer to this link

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

SERIAL CAN BUS MODULE

Introduction¶

Version Track¶

CAN BUS PRODUCTS LIST OF LONGAN-LABS¶

Partlist¶

Features¶

Hardware Overview¶

120 Terminal resistor¶

Work at 3.3V¶

V1.3 Version¶

V1.1 and V1.2 Verstion¶

V1.0 Version¶

AT Command¶

Set the Baud Rate of UART¶

Set CAN Bus Baudrate¶

Set Mask¶

Set Filt¶

Working Mode¶

Send¶

Recv¶

Work with Arduino¶

120Ω Terminal Resistor¶

Hardware Connection¶

Software¶

Test the board¶

Get data from a Vehicle¶

Working Standalone¶

FAQ¶

Schematic Online Viewer¶

Reference¶