Matrix - RTC

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1 Introduction

• The Matrix RTC module is a real time clock module. It uses the low power consumption chip DS1307 with valid up to 2100 56 byte nonvolatile RAM for data storage and 2-wire IIC serial interface
• It counts seconds, minutes, hours, date of the month, month, day of the week, and year with leap year compensation.

2 Features

• I2C serial interface
• 56-byte nonvolatile RAM
• 8-Pin DIP and 8-Pin SO
• Working temperature: -40 degree Celsius to 85 degree Celsius
• PCB dimension(mm): 24 x 32

• Pin Description:

Pin	Description
SDA	I2C SDA
SCL	I2C SCL
5V	Supply Voltage 5V
GND	Ground

4 Applications

4.1 Connect to NanoPi M1

Refer to the following connection diagram to connect the module to the NanoPi M1:

Connection Details:

Matrix-RTC	NanoPi M1
SDA	Pin3
SCL	Pin5
5V	Pin4
GND	Pin6

4.2 Connect to NanoPi 2

Refer to the following connection diagram to connect the module to the NanoPi 2:

Connection Details:

Matrix-RTC	NanoPi 2
SDA	Pin3
SCL	Pin5
5V	Pin4
GND	Pin6

4.3 Connect to NanoPi M2 / NanoPi 2 Fire

Refer to the following connection diagram to connect the module to the NanoPi M2/ NanoPi 2 Fire:

Connection Details:

	NanoPi M2
SDA	Pin3
SCL	Pin5
5V	Pin4
GND	Pin6

4.4 Connect to NanoPC-T2

Refer to the following connection diagram to connect the module to the NanoPC-T2:
Matrix-RTC_NanoPC-T2

Connection Details:

Matrix-RTC	NanoPC-T2
SDA	Pin6
SCL	Pin5
5V	Pin29
GND	Pin30

5 Compile & Run Test Program

Boot your ARM board with Debian and copy the matrix code:

$ apt-get update && apt-get install git
$ git clone https://github.com/friendlyarm/matrix.git

If your cloning is done successfully a "matrix" directory will be generated.

Compile and install Matrix:

$ cd matrix
$ make && make install

Run test program:

$ matrix-rtc

Note: this module is not plug and play therefore before running the module please make sure it is connected to an ARM board.
Here is what you should observe:

RTC Driver Test Example.
Set RTC date/time is 9-15-2015, 01:01:01.
Read RTC date/time is 9-15-2015, 01:01:01.
Test complete

This program reads date/time from and writes date/time to the RTC module. If you want to set the date/time and save it in the RTC module under Debian you can try the following commands. For example if you want to set the date to "2016-11-17 17:26:01" and save it in the RTC module you can do it this way:

$ modprobe rtc-ds1307
$ date -s "2016-11-17 17:26:01"
$ hwclock -w -f /dev/rtc-ds1307

Open the /etc/modprobe.d/matrix-blacklist.conf file and add a "#" in front of "blacklist rtc_ds1307" to comment this line. After you reboot your board the changed date/time will be effective

$ hwclock -r -f /dev/rtc-ds1307
2016 11 18 Friday 08:29:48  -0.492649 seconds

6 Code Sample

This Matrix code sample can work with all the ARM boards mentioned in this module's wiki. The name of this code sample is "matrix-rtc". Here is its source code:

int main(int argc, char **argv)
{
    int fd, retval, board;
    struct rtc_time rtc_tm;
    const char *rtc = default_rtc;
    const char *date_time = default_date_time;
 
    if ((board = boardInit()) < 0) {
        printf("Fail to init board\n");
        return -1;
    }
 
    switch (argc) {
    case 3:
        rtc = argv[1];
        date_time = argv[2];
        break;
    case 1:
        break;
    default:
        fprintf(stderr, "usage:  rtctest [rtcdev] [year mon day hour min sec]\n");
        return 1;
    }
    system("modprobe "DRIVER_MODULE);
    fd = open(rtc, O_RDONLY);
    if (fd ==  -1) {
        perror(rtc);
        goto err;
    }
    fprintf(stderr, "RTC Driver Test Example.\n");
 
    sscanf(date_time, "%d %d %d %d %d %d",
            &rtc_tm.tm_year,
            &rtc_tm.tm_mon,
            &rtc_tm.tm_mday,
            &rtc_tm.tm_hour,
            &rtc_tm.tm_min,
            &rtc_tm.tm_sec); 
    rtc_tm.tm_year -= 1900;
    rtc_tm.tm_mon -= 1;
    retval = ioctl(fd, RTC_SET_TIME, &rtc_tm);
    if (retval == -1) {
        perror("RTC_SET_TIME ioctl");
        goto err;
    }
 
    fprintf(stderr, "Set RTC date/time is %d-%d-%d, %02d:%02d:%02d.\n",
            rtc_tm.tm_mon + 1, rtc_tm.tm_mday, rtc_tm.tm_year + 1900,
            rtc_tm.tm_hour, rtc_tm.tm_min, rtc_tm.tm_sec);
 
    /* Read the RTC time/date */
    retval = ioctl(fd, RTC_RD_TIME, &rtc_tm);
    if (retval == -1) {
        perror("RTC_RD_TIME ioctl");
        goto err;
    }
 
    fprintf(stderr, "Read RTC date/time is %d-%d-%d, %02d:%02d:%02d.\n",
            rtc_tm.tm_mon + 1, rtc_tm.tm_mday, rtc_tm.tm_year + 1900,
            rtc_tm.tm_hour, rtc_tm.tm_min, rtc_tm.tm_sec);
 
    fprintf(stderr, "Test complete\n");
    close(fd);
err:
    system("rmmod "DRIVER_MODULE);
    return 0;
}

For more details about this APIs called in this code sample refer to Matrix API reference manual

7 Resources

DS1307.pdf

8 Update Log

8.1 June-24-2016

• Created English wiki