LCD1602A 显示器 显示时钟和IP（显示所有连接） 树莓派3

LCD1602A 显示器和树莓派通信方式为i2c形式的，i2c是一种串行总线。有串行数据线（SDA），串行时钟线（SCL），电源和接地与设备连接。文章内容为：设备演示图，设备接线图，相关代码。

硬件:树莓派3 LCD1602A显示器 网线 树莓电源。DIY了一下，将显示器放到了外壳的上盖面了。

显示器与pi3间使用i2c通信

设备接线：

ip显示方式 e为有线地址：

w为无线显示 同时连接时循环两秒显示：

未连接网络

pi3与电脑间网线直连,将电脑IP地址改到与pi3同一网段也可以使用vnc

源代码来自GitHub,代码c++经过简单修改而来

源GitHub链接

根据源链接说明，编译文件后，可执行文件在bin目录，根据格式执行就可以。

$ cd ipClock/src
$ make install
$ ipClock -a27 -f1
$ killall ipClock

Raspberry i2c命令：

https://tl8517.com/raspberrypi-command

cron 选择编辑器及开机启动配置，不能开机启动：

https://tl8517.com/cron

下面是我修改后的代码：

//修改后的
#include "main.h"
static unsigned int lcdAddress;
static int          tries = 5;
static char         dateFormat = '1';
static volatile int lcdHandle;
int marquee = 0;
#define lcdWidth 16
#define maxMessageSize 128
char msg[1024];
bool usage() {
    fprintf(stderr, "usage: lcdClock [-d] [-a 00-FF] [-p 0-40] [-f n] [-s speed] [-m motd]\n");
    fprintf(stderr, "a = hexadecimal i2c address ($gpio i2cd)\n");
    fprintf(stderr, "f = clock format\n");
    fprintf(stderr, "    1 - Weekday Month Date HH24:MM\n");
    fprintf(stderr, "    2 - Weekday Date  HH:MM AM/PM\n");
    return false;
}
bool setup() {
    if (int ret = wiringPiSetup()) {
        fprintf(stderr, "Wiring Pi setup failed, ret=%d\n", ret);
        return false;
    }
    int seed;
    FILE *fp;
    fp = fopen("/dev/urandom", "r");
    fread(&seed, sizeof(seed), 1, fp);
    fclose(fp);
    srand(seed);
    //  the following statements setup the proper input or output for their respective
    //  inputs or outputs
    lcdHandle=lcdSetup(lcdAddress);
    if (lcdHandle < 0) {
        fprintf(stderr, "lcdInit failed\n");
        return false;
    }
    return true;
}
bool commandLineOptions(int argc, char **argv) {
    int c, index;
    if (argc < 2) {
        return usage();
    }
    while ((c = getopt(argc, argv, "a:f:")) != -1)
        switch (c) {
            case 'a':
                if (strcmp(optarg, "0x") == 0) {
                    sscanf(&optarg[2], "%x", &lcdAddress);
                } else {
                    sscanf(optarg, "%x", &lcdAddress);
                }
                break;
            case 'f':
                dateFormat = optarg[0];
                break;
            case '?':
                if (optopt == 'a'  optopt == 'p'  optopt == 'f'  optopt == 'm'  optopt == 's')
                    fprintf(stderr, "Option -%c requires an argument.\n", optopt);
                else if (isprint(optopt))
                    fprintf(stderr, "Unknown option `-%c'.\n", optopt);
                else
                    fprintf(stderr, "Unknown option character \\x%x.\n", optopt);
                return usage();
            default:
                abort();
        }
    //for (index = optind; index < argc; index++)
    //printf("Non-option argument %s\n", argv[index]);
    return true;
}
static uint8_t sizecvt(const int read)
{
    /* digitalRead() and friends from wiringpi are defined as returning a value
       < 256. However, they are returned as int() types. This is a safety function */
    if (read > 255  read < 0)
    {
        printf("Invalid data from wiringPi library\n");
        exit(EXIT_FAILURE);
    }
    return (uint8_t)read;
}
void updateClock() {
    auto now = std::chrono::system_clock::now();
    std::time_t end_time = std::chrono::system_clock::to_time_t(now);
    char vtime[64];
    switch (dateFormat) {
        case '2':std::strftime(vtime, 64, "%a %e  %I:%M %p", std::localtime(&end_time));
                    break;
        default:
                    if (std::localtime(&end_time)->tm_mday < 10) {
                        char xtime[64];
                        std::strftime(xtime, 64, "%a %b %%d  %H:%M", std::localtime(&end_time));
                        sprintf(vtime, xtime, std::localtime(&end_time)->tm_mday);
                    }
                    else {
                        std::strftime(vtime, 64, "%a %b %e %H:%M", std::localtime(&end_time));
                    }
    }
    lcdPosition(lcdHandle, 0, 0);           //Position cursor on the first line in the first column
    if (strlen(vtime) > 16) {
        vtime[16] = 0;
    }
    lcdPuts(lcdHandle, vtime);  //Print the text on the LCD at the current cursor postion
    FILE *input;
    char  wlan[256]="";
    char  eth0[256]="";
    lcdPosition(lcdHandle, 0, 1);
    input = popen("/sbin/ifconfig eth0  awk '{if ($1==\"inet\") printf(\"%s\", $2)}'", "r");
    fgets(eth0, 255, input);
    fclose(input);
    lcdPosition(lcdHandle, 0, 1);
    input = popen("/sbin/ifconfig wlan0  awk '{if ($1==\"inet\") printf(\"%s\", $2)}'", "r");
    fgets(wlan, 255, input);
    fclose(input);
    if (strlen(eth0) > 0 & strlen(wlan) > 0){
        lcdPrintf(lcdHandle, "w%s\n", wlan);
        sleep(2);
        lcdPuts(lcdHandle, vtime);  //Print the text on the LCD at the current cursor postion
        lcdPrintf(lcdHandle, "e%s\n", eth0);
        sleep(2);
    } else {
        if (strlen(eth0) > 0){
            lcdPrintf(lcdHandle, "e%s\n", eth0);
            sleep(2);
        }else{
            if (strlen(wlan) > 0){
                lcdPrintf(lcdHandle, "w%s\n",wlan );
                sleep(2);
            }else{
                lcdPrintf(lcdHandle,"*No Connection*\n");
            }
        }
    }
}
int main(int argc, char **argv)
{
    int i;
    if (!commandLineOptions(argc, argv)) {
        return 1;
    }
    if (!setup()) {
        printf("setup failed\n");
        return 1;
    }
    printf("Press ^c to exit IP Clock\n");
    while (1) {
        updateClock();
        //delay(1000);
    }
    return 0;
}

树莓派3更多模块请点击链接：

从入门到放弃的学习RASPBERRYPI