產(chǎn)品概述

RS485 CAN HAT 是微雪電子為樹(shù)莓派開(kāi)發(fā)的一款的帶 RS485 和 CAN 通信功能的擴(kuò)展板，具備 RS485登刺、CAN 通信功能。

特點(diǎn)

• 基于Raspberry Pi 40pin GPIO接口嗡呼，適用于Raspberry Pi系列主板
• 具備CAN功能纸俭，使用SPI接口CAN控制器MCP2515，搭配收發(fā)器SN65HVD230
• 具備RS485功能南窗，使用UART控制揍很，半雙工通訊，收發(fā)器為SP3485
• 板載TVS(瞬態(tài)電壓抑制管)万伤，RS485通訊可有效抑制電路中的浪涌電壓和瞬態(tài)尖峰電壓窒悔，防雷防靜電
• 預(yù)留控制接口，方便其他控制器控制
• 提供完善的配套資料手冊(cè)(提供wiringPi與python例程)

產(chǎn)品參數(shù)

• 工作電壓： 3.3V
• CAN控制芯片： MCP2515
• CAN收發(fā)器： SN65HVD230
• 485收發(fā)器： SP3485
• 產(chǎn)品尺寸： 65mmx30mm
• 固定孔通經(jīng)： 3.0mm

接口說(shuō)明

• CAN總線

| 功能引腳 | 樹(shù)莓派接口（BCM） | 描述 |
| 3V3 | 3V3 | 3.3V電源正 |
| GND | GND | 電源地 |
| SCK | SCK | SPI時(shí)鐘輸入 |
| MOSI | MOSI | SPI數(shù)據(jù)輸入 |
| MISO | MISO | SPI數(shù)據(jù)輸出 |
| CS | CE0 | 數(shù)據(jù)/命令選擇 |
| INT | 25 | 中斷輸出 |

• RS485總線

| 功能引腳 | 樹(shù)莓派接口（BCM） | 描述 |
| 3V3 | 3V3 | 3.3V電源正 |
| GND | GND | 電源地 |
| RXD | RXD | 串口接收 |
| TXD | TXD | 串口發(fā)送 |
| RSE | 4 | 設(shè)置收發(fā) |

對(duì)于RSE引腳敌买，可以選擇不使用简珠，模塊出廠默認(rèn)使用的是硬件自動(dòng)接收與發(fā)送。

硬件說(shuō)明

CAN總線

CAN 模塊的功能是處理所有 CAN 總線上的報(bào)文接收和發(fā)送虹钮。報(bào)文發(fā)送時(shí)北救，首先將報(bào)文裝載到正確的報(bào)文緩沖器和控制寄存器中荐操。通過(guò) SPI 接口設(shè)置控制寄存器中的相應(yīng)位或使用發(fā)送使能引腳均可啟動(dòng)發(fā)送操作。通過(guò)讀取相應(yīng)的寄存器可以檢查通訊狀態(tài)和錯(cuò)誤珍策。 會(huì)對(duì)在 CAN總線上檢測(cè)到的任何報(bào)文進(jìn)行錯(cuò)誤檢查，然后與用戶定義的濾波器進(jìn)行匹配宅倒，以確定是否將報(bào)文移到兩個(gè)接收緩沖器中的一個(gè)攘宙。
由于樹(shù)莓派本身并不支持CAN總線，因此使用SPI接口的CAN控制器拐迁，搭配一個(gè)收發(fā)器完成CAN功能蹭劈。 Microchip 的 MCP2515 是一款CAN協(xié)議控制器，完全支持 CAN V2.0B 技術(shù)規(guī)范线召。該器件能發(fā)送和接收標(biāo)準(zhǔn)和擴(kuò)展數(shù)據(jù)幀以及遠(yuǎn)程幀铺韧。 MCP2515 自帶的兩個(gè)驗(yàn)收屏蔽寄存器和六個(gè)驗(yàn)收濾波寄存器可以過(guò)濾掉不想要的報(bào)文，因此減少了主單片機(jī)（MCU）的開(kāi)銷(xiāo)缓淹。MCU通過(guò)SPI接口與該器件連接,即樹(shù)莓派通過(guò)SPI接口連接芯片哈打，對(duì)于樹(shù)莓派使用該芯片不需要編寫(xiě)驅(qū)動(dòng)，只需要打開(kāi)設(shè)備樹(shù)中的內(nèi)核驅(qū)動(dòng)即可使用讯壶。

RS485 CAN HAT MCP2515.png

RS485 CAN HAT SN65HVD230.png

RS485總線

SP3485接口芯片是一種RS-485驅(qū)動(dòng)芯片凳怨。用于RS-485通信的低功耗收發(fā)器瑰艘。 采用單一電源+3.3V工作，采用半雙工通訊方式肤舞。RO和DI端分別為接收器的輸出和驅(qū)動(dòng)器的輸入端紫新；(RE) ?和DE端分別為接收和發(fā)送的使能端，當(dāng)(RE) ?為邏輯0時(shí)李剖，器件處于接收狀態(tài)芒率；當(dāng)DE為邏輯1時(shí)，器件處于發(fā)送狀態(tài)篙顺；A端和B端分別為接收和發(fā)送的差分信號(hào)端偶芍，當(dāng)A-B>+0.2V時(shí)充择，RO輸出邏輯1；當(dāng)A-B<-0.2V時(shí)匪蟀，RO輸出邏輯0椎麦。A和B端之間加匹配電阻，一般可選100Ω的電阻材彪。

RS485 CAN HAT 485.png

RS485 CAN HAT 485SR.png

樹(shù)莓派使用

安裝庫(kù)

• 安裝BCM2835蕴潦， 打開(kāi)樹(shù)莓派終端，并運(yùn)行一下指令

1. wget http://www.airspayce.com/mikem/bcm2835/bcm2835-1.60.tar.gz

2. tar zxvf bcm2835-1.60.tar.gz
3. cd bcm2835-1.60/
4. sudo ./configure
5. sudo make
6. sudo make check
7. sudo make install
8. 更多的可以參考官網(wǎng)：http://www.airspayce.com/mikem/bcm2835/

• 安裝wiringPi

1. sudo apt-get install wiringpi

2. 對(duì)于樹(shù)莓派4B可能需要進(jìn)行升級(jí)：

3. wget https://project-downloads.drogon.net/wiringpi-latest.deb
4. sudo dpkg -i wiringpi-latest.deb
5. gpio -v
6. 運(yùn)行g(shù)pio -v會(huì)出現(xiàn)2.52版本俘闯，如果沒(méi)有出現(xiàn)說(shuō)明安裝出錯(cuò)

• python

1. sudo apt-get update

2. sudo apt-get install python-serial
3. sudo pip install python-can

下載例程

在樹(shù)莓派終端運(yùn)行：

1. sudo apt-get install p7zip-full

2. wget http://www.waveshare.net/w/upload/d/de/RS485_CAN_HAT_Code.7z
3. 7z x RS485_CAN_HAT_Code.7z -r -o./RS485_CAN_HAT_Code
4. sudo chmod 777 -R RS485_CAN_HAT_Code/

CAN使用

本演示程序使用了兩個(gè)樹(shù)莓派以及兩個(gè)RS485 CAN HAT模塊
提供python與c語(yǔ)言程序

前置工作

將模塊插在樹(shù)莓派上潭苞，然后修改開(kāi)機(jī)腳本config.txt

1. sudo nano /boot/config.txt

在最后一行加入如下：

1. dtparam=spi=on

2. dtoverlay=mcp2515-can0,oscillator=12000000,interrupt=25,spimaxfrequency=2000000

其中oscillator=12000000，是板載的晶振大小12M真朗，如下圖

RS485 CAN HAT cry12.png

• 如果購(gòu)買(mǎi)日期早于2019年8月份此疹，請(qǐng)使用下面的：

如圖，紅色框內(nèi)為8M的晶振

RS485 CAN HAT cry.png

1. dtparam=spi=on

2. dtoverlay=mcp2515-can0,oscillator=8000000,interrupt=25,spimaxfrequency=1000000

保存退出后，重啟樹(shù)莓派：

1. sudo reboot

重啟后蝗碎，運(yùn)行命令查看是否初始化成功：

1. dmesg | grep -i '(can|spi)'

RS485 CAN HAT CAN1.png

RS485 CAN HAT CAN2.png

C

• 阻塞接收脊串，樹(shù)莓派打開(kāi)終端辫呻，運(yùn)行：

1. cd RS485_CAN_HAT_Code/RS485_CAN_HAT_Code/CAN/wiringPi/receive/

2. make clean
3. make
4. sudo ./can_receive

接收程序是阻塞的，直到讀取到數(shù)據(jù)就結(jié)束琼锋。

RS485 CAN HAT CAN reveive.png

• 發(fā)送，樹(shù)莓派打開(kāi)終端祟昭，運(yùn)行：

1. cd RS485_CAN_HAT_Code/RS485_CAN_HAT_Code/CAN/wiringPi/receive/

2. make clean
3. make
4. sudo ./can_send

RS485 CAN HAT CAN send.png

此時(shí)接收接收到對(duì)應(yīng)的id的報(bào)文：

RS485 CAN HAT CAN reveive1.png

python

樹(shù)莓派打開(kāi)終端缕坎，運(yùn)行：

1. cd RS485_CAN_HAT_Code/RS485_CAN_HAT_Code/CAN/python/

2. 先運(yùn)行接收：

3. sudo python can_reveive.py

4. 發(fā)送端：

5. sudo python can_send.py

RS485使用

本演示程序使用了兩個(gè)樹(shù)莓派以及兩個(gè)RS485 CAN HAT模塊
提供python與wiringPi語(yǔ)言程序

前置工作

開(kāi)啟Uart接口

打開(kāi)樹(shù)莓派終端，輸入以下指令進(jìn)入配置界面

1. sudo raspi-config

2. 選擇Interfacing Options -> Serial篡悟，關(guān)閉shell訪問(wèn)谜叹，打開(kāi)硬件串口

</pre>

L76X GPS Module rpi serial.png

然后重啟樹(shù)莓派：

1. sudo reboot

打開(kāi)/boot/config.txt文件，找到如下配置語(yǔ)句使能串口搬葬，如果沒(méi)有荷腊，可添加在文件最后面。

1. enable_uart=1

對(duì)于樹(shù)莓派3B用戶急凰，串口用于藍(lán)牙女仰，需要注釋掉：

1. dtoverlay=pi3-miniuart-bt

然后重啟樹(shù)莓派：

1. sudo reboot

確定好兩邊樹(shù)莓派都這樣處理了，把兩個(gè)模塊的A與B對(duì)應(yīng)連接
如果使用的是其他的485設(shè)備抡锈，確定連線A-A,B-B即可

C

• 阻塞接收疾忍，樹(shù)莓派打開(kāi)終端，運(yùn)行：

1. cd RS485_CAN_HAT_Code/RS485_CAN_HAT_Code/485/WiringPi/send

2. make clean
3. make
4. sudo ./485_receive

接收程序是阻塞的床三，直到讀取到數(shù)據(jù)就結(jié)束一罩。

RS485 CAN HAT 485 receive.png

• 發(fā)送，樹(shù)莓派打開(kāi)終端撇簿，運(yùn)行：

1. cd RS485_CAN_HAT_Code/RS485_CAN_HAT_Code/485/WiringPi/send

2. make clean
3. make
4. sudo ./485_send

此時(shí)接收端接收到程序

RS485 CAN HAT 485 receive2.png

python例程

1. cd RS485_CAN_HAT_Code/RS485_CAN_HAT_Code/485/python/

2. 先運(yùn)行接收：

3. sudo python reveive.py

4. 發(fā)送端：

5. sudo python send.py

故障排查

如果485通信不正常聂渊，請(qǐng)分步調(diào)試：

1. 確定樹(shù)莓派的硬件版本，如果是樹(shù)莓派ZERO/3B四瘫，則程序中的串口需要修改成/dev/ttyAMA0汉嗽；
2. 確定485的A,B是否與控制的485設(shè)備A,B一一對(duì)應(yīng)；
3. 可以先使用USB to 485設(shè)備與RS485 CAN HAT通信莲组，保證樹(shù)莓派的設(shè)置沒(méi)有問(wèn)題诊胞；

原理圖

Can485原理圖.JPG

485Demo

receive.py

# -*- coding:utf-8 -*-
import RPi.GPIO as GPIO
import serial
import time

#if use half-auto, EN_485 = LOW is Receiver, EN_485 = HIGH is Send
MODE = 0 #mode = 0 is full-guto, mode = 1 is half-auto
if MODE == 1:
    EN_485 =  4
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(EN_485,GPIO.OUT)
    GPIO.output(EN_485,GPIO.HIGH)

ser = serial.Serial("/dev/ttyS0",115200,timeout=0.01) #receive data once every 0.01S 
print ser.portstr

ser.flushInput()

data = ""
print("You can always receive data, press Ctrl + C to exit")
while 1: 
    while ser.inWaiting() > 0:
        data = ser.readline()
    if data != "":
        print(data)
        data = ""

send.py

# -*- coding:utf-8 -*-
import RPi.GPIO as GPIO
import serial

#if use half-auto, EN_485 = LOW is Receiver, EN_485 = HIGH is Send
MODE = 0 #mode = 0 is full-guto, mode = 1 is half-auto
if MODE == 1:
    EN_485 =  4
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(EN_485,GPIO.OUT)
    GPIO.output(EN_485,GPIO.HIGH)

ser = serial.Serial("/dev/ttyS0",115200,timeout=1) 
print ser.portstr

command = "hello world"
print("send:"),command  
len = ser.write(command)    
print("len = "),len

print("You can always send data, press Ctrl + C to exit")
while 1:
    strInput = raw_input('enter some words:')  
    ser.write(strInput)

ser.flush()

485_receive.c

#include <wiringSerial.h>
#include <wiringPi.h>
#include <stdio.h>
#include <stdlib.h>     //exit()
#include <signal.h>
#include <unistd.h>
#include <string.h>
#include <strings.h>
#include <sys/time.h>

// if use half-auto, EN_485 = LOW is Receiver, EN_485 = HIGH is Send
#define MODE 0 //mode = 0 is full-guto, mode = 1 is half-auto
#define EN_485 4
#define UART_DEV "/dev/ttyS0"

int fd;

void  Handler(int signo)
{
    //System Exit
    printf("\r\nHandler:serialClose \r\n");
    serialClose(fd);

    exit(0);
}

int main(void)
{
    // Exception handling:ctrl + c
    signal(SIGINT, Handler);

    if(MODE == 1){
        if(wiringPiSetupGpio() < 0) { //use BCM2835 Pin number table
            printf("set wiringPi lib failed !!! \r\n");
            return 1;
        } else {
            printf("set wiringPi lib success  !!! \r\n");
        }
        pinMode(EN_485, OUTPUT);
        digitalWrite(EN_485,LOW);
    }

    if((fd = serialOpen(UART_DEV, 115200)) < 0) {
        printf("serial err\n");
        return -1;
    }
    printf("use device %s\r\n", UART_DEV);

    printf("You can always receive data, press Ctrl + C to exit\r\n");
    char str;
    for (;;) {
        str = serialGetchar(fd);
        if(str < 128) // ascii
            printf("%c", str);
        fflush(stdout); // Empty the output buffer and output the contents of the buffer
    }
    return 0;
}

485_send.c

#include <wiringSerial.h>
#include <wiringPi.h>
#include <stdio.h>
#include <stdlib.h>     //exit()
#include <signal.h>
#include <unistd.h>
#include <string.h>
#include <strings.h>
#include <sys/time.h>

// if use half-auto, EN_485 = LOW is Receiver, EN_485 = HIGH is Send
#define MODE 0 //mode = 0 is full-guto, mode = 1 is half-auto
#define EN_485 4
#define UART_DEV "/dev/ttyS0"

int fd;

void  Handler(int signo)
{
    //System Exit
    printf("\r\nHandler:serialClose \r\n");
    serialClose(fd);

    exit(0);
}

int main(void)
{
    if(MODE == 1){
        if(wiringPiSetupGpio() < 0) { //use BCM2835 Pin number table
            printf("set wiringPi lib failed !!! \r\n");
            return 1;
        } else {
            printf("set wiringPi lib success  !!! \r\n");
        }
        pinMode(EN_485, OUTPUT);
        digitalWrite(EN_485,HIGH);
    }

    printf("use device %s\r\n", UART_DEV);
    if((fd = serialOpen(UART_DEV, 115200)) < 0) {
        printf("serial err\n");
        return -1;
    }

    serialFlush(fd);
    serialPrintf(fd,"\r");
    char str[] = "hello world\n";
    printf("send data：%s\r\n", str);
    serialPuts(fd, str);

    char str_buf[100];
    printf("You can always receive data, press Ctrl + C to exit\r\n");
    printf("You can enter up to %d characters\r\n", sizeof(str_buf));
    for(;;){        
        scanf("%s", str_buf); 
        strcat(str_buf,"\n"); //Add newline
        serialPuts(fd, str_buf);
    }

    serialClose(fd);
    return 0;
}

can_receive.py

import os
import can

os.system('sudo ip link set can0 type can bitrate 100000')
os.system('sudo ifconfig can0 up')

can0 = can.interface.Bus(channel = 'can0', bustype = 'socketcan_ctypes')# socketcan_native

#msg = can.Message(arbitration_id=0x123, data=[0, 1, 2, 3, 4, 5, 6, 7], extended_id=False)
msg = can0.recv(10.0)
print msg
if msg is None:
    print('Timeout occurred, no message.')

os.system('sudo ifconfig can0 down')

can_send.py

import os
import can

os.system('sudo ip link set can0 type can bitrate 100000')
os.system('sudo ifconfig can0 up')

can0 = can.interface.Bus(channel = 'can0', bustype = 'socketcan_ctypes')# socketcan_native

msg = can.Message(arbitration_id=0x123, data=[0, 1, 2, 3, 4, 5, 6, 7], extended_id=False)
can0.send(msg)

os.system('sudo ifconfig can0 down')

can_receive.c

```cpp
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <linux/can.h>
#include <linux/can/raw.h>

int main()
{
    int ret;
    int s, nbytes;
    struct sockaddr_can addr;
    struct ifreq ifr;
    struct can_frame frame;
    
    memset(&frame, 0, sizeof(struct can_frame));
    
    system("sudo ip link set can0 type can bitrate 100000");
    system("sudo ifconfig can0 up");
    printf("this is a can receive demo\r\n");
    
    //1.Create socket
    s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
    if (s < 0) {
        perror("socket PF_CAN failed");
        return 1;
    }
    
    //2.Specify can0 device
    strcpy(ifr.ifr_name, "can0");
    ret = ioctl(s, SIOCGIFINDEX, &ifr);
    if (ret < 0) {
        perror("ioctl failed");
        return 1;
    }

    //3.Bind the socket to can0
    addr.can_family = PF_CAN;
    addr.can_ifindex = ifr.ifr_ifindex;
    ret = bind(s, (struct sockaddr *)&addr, sizeof(addr));
    if (ret < 0) {
        perror("bind failed");
        return 1;
    }
    
    //4.Define receive rules
    struct can_filter rfilter[1];
    rfilter[0].can_id = 0x123;
    rfilter[0].can_mask = CAN_SFF_MASK;
    setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, &rfilter, sizeof(rfilter));

    //5.Receive data and exit
    while(1) {
        nbytes = read(s, &frame, sizeof(frame));
        if(nbytes > 0) {
            printf("can_id = 0x%X\r\ncan_dlc = %d \r\n", frame.can_id, frame.can_dlc);
            int i = 0;
            for(i = 0; i < 8; i++)
                printf("data[%d] = %d\r\n", i, frame.data[i]);
            break;
        }
    }
    
    //6.Close the socket and can0
    close(s);
    system("sudo ifconfig can0 down");
    
    return 0;
}

can_send.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <linux/can.h>
#include <linux/can/raw.h>

int main()
{
    int ret;
    int s, nbytes;
    struct sockaddr_can addr;
    struct ifreq ifr;
    struct can_frame frame;
    memset(&frame, 0, sizeof(struct can_frame));

    system("sudo ip link set can0 type can bitrate 100000");
    system("sudo ifconfig can0 up");
    printf("this is a can send demo\r\n");
        
    //1.Create socket
    s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
    if (s < 0) {
        perror("socket PF_CAN failed");
        return 1;
    }
    
    //2.Specify can0 device
    strcpy(ifr.ifr_name, "can0");
    ret = ioctl(s, SIOCGIFINDEX, &ifr);
    if (ret < 0) {
        perror("ioctl failed");
        return 1;
    }
    
    //3.Bind the socket to can0
    addr.can_family = AF_CAN;
    addr.can_ifindex = ifr.ifr_ifindex;
    ret = bind(s, (struct sockaddr *)&addr, sizeof(addr));
    if (ret < 0) {
        perror("bind failed");
        return 1;
    }
    
    //4.Disable filtering rules, do not receive packets, only send
    setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, NULL, 0);

    //5.Set send data
    frame.can_id = 0x123;
    frame.can_dlc = 8;
    frame.data[0] = 1;
    frame.data[1] = 2;
    frame.data[2] = 3;
    frame.data[3] = 4;
    frame.data[4] = 5;
    frame.data[5] = 6;
    frame.data[6] = 7;
    frame.data[7] = 8;
    
    printf("can_id  = 0x%X\r\n", frame.can_id);
    printf("can_dlc = %d\r\n", frame.can_dlc);
    int i = 0;
    for(i = 0; i < 8; i++)
        printf("data[%d] = %d\r\n", i, frame.data[i]);
    
    //6.Send message
    nbytes = write(s, &frame, sizeof(frame)); 
    if(nbytes != sizeof(frame)) {
        printf("Send Error frame[0]!\r\n");
        system("sudo ifconfig can0 down");
    }
    
    //7.Close the socket and can0
    close(s);
    system("sudo ifconfig can0 down");
    return 0;
}