velometer/ds1302.c

#include "ds1302.h"

void _prepare_read(uint8_t address);
void _prepare_write(uint8_t address);
uint8_t _read_byte();
void _write_byte(uint8_t value);
void _make_clock_cycle();

void _end_transfer();

#define REG_SECONDS 0x80 // SEC
#define REG_MINUTES 0x82 // MIN
#define REG_HOUR 0x84    // HR
#define REG_DATE 0x86    // DATE
#define REG_MONTH 0x88   // MONTH
#define REG_DAY 0x8A     // DAY
#define REG_YEAR 0x8C    // YEAR
#define REG_WP 0x8E      // CONTROL
// TRICKLE CHARGER 1001000_ 0x90
#define REG_BURST 0xBE // CLOCK BURST

#define REG_RAM00 0xC0
#define REG_RAM_BURST 0xFE

void ds1302_init() {
  gpio_init(PIN_RTC_RESET);
  gpio_set_dir(PIN_RTC_RESET, GPIO_OUT);
  gpio_put(PIN_RTC_RESET, LOW);

  gpio_init(PIN_RTC_CLOCK);
  gpio_set_dir(PIN_RTC_CLOCK, GPIO_OUT);
  gpio_put(PIN_RTC_CLOCK, LOW);

  gpio_init(PIN_RTC_IO);
  gpio_set_dir(PIN_RTC_IO, GPIO_IN);
}

int ds1302_is_clock_halted() {
  _prepare_read(REG_SECONDS);
  uint8_t seconds = _read_byte();
  _end_transfer();
  return (seconds & 0b10000000);
}

void ds1302_get_datetime(DateTime *dt) {
  _prepare_read(REG_BURST);
  dt->second = ds1302_decode_bcd(_read_byte() & 0b01111111);
  dt->minute = ds1302_decode_bcd(_read_byte() & 0b01111111);
  dt->hour = ds1302_decode_bcd(_read_byte() & 0b00111111);
  dt->day = ds1302_decode_bcd(_read_byte() & 0b00111111);
  dt->month = ds1302_decode_bcd(_read_byte() & 0b00011111);
  dt->dow = ds1302_decode_bcd(_read_byte() & 0b00000111);
  dt->year = ds1302_decode_bcd(_read_byte() & 0b01111111);
  _end_transfer();
}

void ds1302_set_datetime(DateTime *dt) {
  // disable write protection
  _prepare_write(REG_WP);
  _write_byte(0b00000000); // 0, false
  _end_transfer();
  // OR call writeProtect(0)

  _prepare_write(REG_BURST);
  _write_byte(ds1302_encode_bcd(dt->second % 60));
  _write_byte(ds1302_encode_bcd(dt->minute % 60));
  _write_byte(ds1302_encode_bcd(dt->hour % 24));
  _write_byte(ds1302_encode_bcd(dt->day % 32));
  _write_byte(ds1302_encode_bcd(dt->month % 13));
  _write_byte(ds1302_encode_bcd(dt->dow % 8));
  _write_byte(ds1302_encode_bcd(dt->year % 100));
  _write_byte(0b10000000);
  _end_transfer();
}

void ds1302_halt() {
  _prepare_write(REG_SECONDS);
  _write_byte(0b10000000);
  _end_transfer();
}

void _prepare_read(uint8_t address) {
  gpio_set_dir(PIN_RTC_IO, GPIO_OUT);
  gpio_put(PIN_RTC_RESET, HIGH);
  uint8_t command = 0b10000001 | address;
  _write_byte(command);
  gpio_set_dir(PIN_RTC_IO, GPIO_IN);
}

void _prepare_write(uint8_t address) {
  gpio_set_dir(PIN_RTC_IO, GPIO_OUT);
  gpio_put(PIN_RTC_RESET, HIGH);
  uint8_t command = 0b10000000 | address;
  _write_byte(command);
}

void _end_transfer() { gpio_put(PIN_RTC_RESET, LOW); }

uint8_t _read_byte() {
  uint8_t byte = 0;
  for (uint8_t b = 0; b < 8; b++) {
    if (gpio_get(PIN_RTC_IO) == HIGH)
      byte |= 0x01 << b;
    _make_clock_cycle();
  }
  return byte;
}

void _write_byte(uint8_t value) {
  for (uint8_t b = 0; b < 8; b++) {
    gpio_put(PIN_RTC_IO, (value & 0x01) ? HIGH : LOW);
    _make_clock_cycle();
    value >>= 1;
  }
}

void _make_clock_cycle() {
  gpio_put(PIN_RTC_CLOCK, HIGH);
  sleep_us(1);
  gpio_put(PIN_RTC_CLOCK, LOW);
  sleep_us(1);
}

void ds1302_get_ram_byte(uint8_t addr, uint8_t *data) {
  _prepare_read(addr);
  *data = _read_byte();
  _end_transfer();
}

void ds1302_set_ram_byte(uint8_t addr, uint8_t *data) {
  _prepare_write(addr);
  _write_byte(*data);
  _end_transfer();
}

void ds1302_set_write_protection(int enable) {
  _prepare_write(REG_WP);
  _write_byte(enable);
  _end_transfer();
}

void ds1302_write_ram_bulk(const uint8_t *data, int len) {
  if (len <= 0 || len > 31) {
    return;
  }
  _prepare_write(REG_RAM_BURST);
  for (int i = 0; i < len; i++) {
    _write_byte(data[i]);
  }
  _end_transfer();
}

void ds1302_read_ram_bulk(uint8_t *data, int len) {
  if (len <= 0 || len > 31) {
    return;
  }
  _prepare_read(REG_RAM_BURST);
  for (int i = 0; i < len; i++) {
    data[i] = _read_byte();
  }
  _end_transfer();
}