File content as of revision 7:4793c4817590:

/*
 * mbed library program
 *  Control RX-8025NB Real Time Clock Module
 *  EPSON
 *
 * Copyright (c) 2015,'16,'17,'19,'20 Kenji Arai / JH1PJL
 *  http://www7b.biglobe.ne.jp/~kenjia/
 *  https://os.mbed.com/users/kenjiArai/
 *      Created: June        3rd, 2015
 *      Revised: August      7th, 2020
 */

#include "mbed.h"
#include "RX8025NB.h"

#define RTC_Wk_Sunday          ((uint8_t)0x00)

RX8025::RX8025 (PinName p_sda, PinName p_scl) :
    _i2c_p(new I2C(p_sda, p_scl)), _i2c(*_i2c_p)
{
    RX8025_addr = RX8025ADDR;
    init();
}

RX8025::RX8025 (I2C& p_i2c) : _i2c(p_i2c)
{
    RX8025_addr = RX8025ADDR;
    init();
}

/////////////// Initialize /////////////////////////////////////////////////////
void RX8025::init()
{
    tm t;
    int8_t dt;

    _i2c.frequency(400000);
    dt = read_reg_byte(RX8025_REG_CONTL2);
    if (dt &  0x10) {  // Power on reset
        dt = write_reg_byte(RX8025_REG_CONTL2, 0);   // all clear
        // Set 24H
        dt = read_reg_byte(RX8025_REG_CONTL1);
        dt |= 0x20;
        dt = write_reg_byte(RX8025_REG_CONTL1, dt);
        // set January 1st,2019 1am as a default
        t.tm_sec  = 0;
        t.tm_min  = 0;
        t.tm_hour = 1;
        t.tm_mday = 1;
        t.tm_wday = 0;
        t.tm_mon  = 0;
        t.tm_year = 119;
        write_rtc_std(&t);
    } else {
        // Set 24H
        dt = read_reg_byte(RX8025_REG_CONTL1);
        if (dt & 0x20) { // set already
            ;
        } else {
            dt |= 0x20;
            dt = write_reg_byte(RX8025_REG_CONTL1, dt);
        }
    }
}

/////////////// Read RTC data //////////////////////////////////////////////////
void RX8025::get_time_rtc (tm *t)
{
    read_rtc_std(t);
}

void RX8025::read_rtc_std (tm *t)
{
    rtc_time time;

    read_rtc_direct(&time);
    t->tm_sec  = time.rtc_seconds;
    t->tm_min  = time.rtc_minutes;
    t->tm_hour = time.rtc_hours;
    t->tm_mday = time.rtc_date;
    if (time.rtc_weekday == RTC_Wk_Sunday) {
        t->tm_wday = 0; // Sun is not 7 but 0
    } else {
        t->tm_wday = time.rtc_weekday;
    }
    t->tm_mon  = time.rtc_month - 1;
    t->tm_year = time.rtc_year_raw + 100;
    t->tm_isdst= 0;
}

/////////////// Write data to RTC //////////////////////////////////////////////
void RX8025::set_time_rtc (tm *t)
{
    write_rtc_std(t);
}

void RX8025::write_rtc_std (tm *t)
{
    rtc_time time;

    time.rtc_seconds  = t->tm_sec;
    time.rtc_minutes  = t->tm_min;
    time.rtc_hours    = t->tm_hour;
    time.rtc_date     = t->tm_mday;
    if ( t->tm_wday == 0) {
        time.rtc_weekday = RTC_Wk_Sunday;
    } else {
        time.rtc_weekday = t->tm_wday;
    }
    time.rtc_month    = t->tm_mon + 1;
    time.rtc_year_raw = t->tm_year - 100;
    write_rtc_direct(&time);
}

/////////////// Set Alarm-D / INTA /////////////////////////////////////////////
void RX8025::set_alarmD_reg (uint16_t time)
{
    tm t;
    int8_t dt;
    uint8_t m, h;
    uint16_t set;

    dt = read_reg_byte(RX8025_REG_CONTL1);
    dt &= ~0x40;        // DALE = 0
    dt = write_reg_byte(RX8025_REG_CONTL1, dt);
    read_rtc_std(&t);   // read current time
    set = time + t.tm_hour * 60 + t.tm_min;
    m = t.tm_min + (uint8_t)(time % 60);
    h = t.tm_hour;
    if (m >= 60) {
        m -= 60;
        h += 1;
    }
    h += (uint8_t)(time / 60);
    if (h >= 24) {
        h -= 24;
    }
    rtc_buf[2] = bin2bcd(h);
    rtc_buf[1] = bin2bcd(m);
    rtc_buf[0] = RX8025_REG_ALARMD_MIN << 4;
    _i2c.write((int)RX8025_addr, (char *)rtc_buf, 3, false);
    dt = read_reg_byte(RX8025_REG_CONTL1);
    dt |= 0x60;         // DALE = 1
    dt = write_reg_byte(RX8025_REG_CONTL1, dt);
}

void RX8025::set_next_IRQ (uint16_t time)
{
    set_next_alarmD_INTA(time);
}

void RX8025::set_next_alarmD_INTA (uint16_t time)
{
    uint16_t t;

    if (time < 2) {
        // Alarm does not check seconds digit.
        // If 59 to 0 is occured during setting here,
        // 1 minute will have a trouble.
        t = 2;
    } else if (time > 1440) {  // set less than 24 hours
        t = 1440;
    } else {
        t = time;
    }
    set_alarmD_reg(t);
}

/////////////// Clear Alarm-D / INTA interrupt /////////////////////////////////
void RX8025::clear_IRQ()
{
    clear_alarmD_INTA();
}

void RX8025::clear_alarmD_INTA ()
{
    int8_t dt, reg;

    for (uint32_t i = 0; i < 40; i++) {
        reg = read_reg_byte(RX8025_REG_CONTL2);
        if ((reg & 0x01) == 0) {
            break;
        }
        dt = reg & 0xfe;
        write_reg_byte(RX8025_REG_CONTL1, dt);
    }
}

/////////////// Read/Write specific register ///////////////////////////////////
uint8_t RX8025::read_reg_byte(uint8_t reg)
{
    rtc_buf[0] = reg << 4;
    _i2c.write((int)RX8025_addr, (char *)rtc_buf, 1, true);
    _i2c.read((int)RX8025_addr, (char *)rtc_buf, 1, false);
    return rtc_buf[0];
}

uint8_t RX8025::write_reg_byte(uint8_t reg, uint8_t data)
{
    rtc_buf[0] = reg << 4;
    rtc_buf[1] = data;
    _i2c.write((int)RX8025_addr, (char *)rtc_buf, 2, false);
    return read_reg_byte(reg);
}

/////////////// I2C Freq. //////////////////////////////////////////////////////
void RX8025::frequency(int hz)
{
    _i2c.frequency(hz);
}

/////////////// Read/Write RTC another format //////////////////////////////////
void RX8025::read_rtc_direct (rtc_time *tm)
{
    rtc_buf[0] = RX8025_REG_SEC << 4;
    _i2c.write((int)RX8025_addr, (char *)rtc_buf, 1, true);
    _i2c.read((int)RX8025_addr, (char *)rtc_buf, 10, false);
    tm->rtc_seconds = bcd2bin(rtc_buf[RX8025_REG_SEC]  & 0x7f);
    tm->rtc_minutes = bcd2bin(rtc_buf[RX8025_REG_MIN]  & 0x7f);
    tm->rtc_hours   = bcd2bin(rtc_buf[RX8025_REG_HOUR] & 0x3f);
    tm->rtc_date    = bcd2bin(rtc_buf[RX8025_REG_DAY]  & 0x3f);
    tm->rtc_weekday = rtc_buf[RX8025_REG_WDAY] & 0x07;
    tm->rtc_month   = bcd2bin(rtc_buf[RX8025_REG_MON]  & 0x1f);
    tm->rtc_year_raw= bcd2bin(rtc_buf[RX8025_REG_YEAR]);
    tm->rtc_year = tm->rtc_year_raw + 100 + 1900;
}

void RX8025::write_rtc_direct (rtc_time *tm)
{
    rtc_buf[RX8025_REG_YEAR + 1] = bin2bcd(tm->rtc_year_raw);
    rtc_buf[RX8025_REG_MON  + 1] = bin2bcd(tm->rtc_month);
    rtc_buf[RX8025_REG_WDAY + 1] = (tm->rtc_weekday & 0x07);
    rtc_buf[RX8025_REG_DAY  + 1] = bin2bcd(tm->rtc_date);
    rtc_buf[RX8025_REG_HOUR + 1] = bin2bcd(tm->rtc_hours);
    rtc_buf[RX8025_REG_MIN  + 1] = bin2bcd(tm->rtc_minutes);
    rtc_buf[RX8025_REG_SEC  + 1] = bin2bcd(tm->rtc_seconds);
    rtc_buf[0] = RX8025_REG_SEC << 4;
    _i2c.write((int)RX8025_addr, (char *)rtc_buf, 8, false);
}

/////////////// Square wave output /////////////////////////////////////////////
void RX8025::set_sq_wave (sq_wave_t sqw_dt)
{
    rtc_buf[0] = RX8025_REG_CONTL1 << 4;
    _i2c.write((int)RX8025_addr, (char *)rtc_buf, 1, true);
    _i2c.read((int)RX8025_addr, (char *)rtc_buf, 2, false);
    if (sqw_dt == RTC_SQW_NONE) {           // FOUT is disable
        rtc_buf[2] = rtc_buf[1] | 0x08;         // CLEN1 = 1
        rtc_buf[1] = rtc_buf[0] | 0x10;         // CLEN2 = 1
        rtc_buf[0] = RX8025_REG_CONTL1 << 4;
        _i2c.write((int)RX8025_addr, (char *)rtc_buf, 3, false);
    } else {   // FOUT is enable
        rtc_buf[2] = rtc_buf[1] & 0xf7;         // CLEN1 = 0
        rtc_buf[1] = rtc_buf[0] & 0xef;         // CLEN2 = 0
        rtc_buf[0] = RX8025_REG_CONTL1 << 4;
        _i2c.write((int)RX8025_addr, (char *)rtc_buf, 3, false);
    }
}

/////////////// conversion BCD & BIN ///////////////////////////////////////////
uint8_t RX8025::bin2bcd (uint8_t dt)
{
    uint8_t bcdhigh = 0;

    while (dt >= 10) {
        bcdhigh++;
        dt -= 10;
    }
    return  ((uint8_t)(bcdhigh << 4) | dt);
}

uint8_t RX8025::bcd2bin (uint8_t dt)
{
    uint8_t tmp = 0;

    tmp = ((uint8_t)(dt & (uint8_t)0xf0) >> (uint8_t)0x4) * 10;
    return (tmp + (dt & (uint8_t)0x0f));
}