Published April 15, 2020 © GPL3+

push Soil Humidity / Moisture to the Apple Homekit

To decide whether watering the garden. Using 433 MHz, battery powered, measuring temperature, air pressure, soil humidity.

IntermediateFull instructions provided10 hours1,544

push Soil Humidity / Moisture to the Apple Homekit

Things used in this project

Hardware components

adafruit RFM69 breakout

Adafruit Feather M0 RFM69

SHT31

DFRobot Gravity: I2C BME280 Environmental Sensor

2N2222 Transistor

Software apps and online services

PlatformIO IDE

RFM69 RadioHead

Microsoft Visual Studio 2017

Story

To watering the garden, when away, could be difficult. And, to know, whether the plants needs water too. I use a cistern and immersion pump. To control the need of watering, this sensor measure soil moisture, temperature etc., send the data via 433 MHz to a bridge. The bridge in turn, send the data to the apple HomeKit. At this way, i can decide to start the immersion pump and watering the garden.

data transmission

After messing around with Wifi and BLE, I decided to use 433 MHz connections for better coverage. The sensor itself stands on the ground between plants (many obstacles and signal reflections). Without obstacles, ISM band communication works up to 500 meters - that's nice.

powering

I want this units battery-powered and rechargeable. In my case, it's enough to get fresh values each 30 minutes. Between that, the unit should "deep sleep". The SAMD21 based boards have an internal and an external oscillator. Using the external, more precise oscillator, i have seen spontaneous RTC freeze. So i modified the RTCZero lib to use the less precise, but more stable internal oscillator OSCULP32K. Along this, the sensor unit goes into deep sleep between the measurements. At least, without charging the unit works around 6 months.

sensor selection

Using the sensor outside, it's a good idea to select a capacitive sensor for measuring soil humidity like the "DFRobot Soil Moisture" or the SHT31 sensor with more accurate values, working via I2C. Other types, especially simple resistor bases sensors are rotten in some weeks.The environment values (temperature, air humidity) measured in this example by AM3202/DHT22 sensor. Later, i replace this sensor by the more accurate BME280 sensor( I2C interface too).

Additionally, to have the sensor unit outside, at all weather conditions, in minimum a IP67 case is needed to prevent water/humidity inside the electronic case.

bridge side

My bridge based on a Raspberry Pi Zero W and the RFM69 breakout board. (meanwhile I have 3 different sensor units with vis versa communication threads. I changed from Pi Zero W to Pi 3B+, because of using python threading/multiprocessing on the bridge for faster communication. The single core Pi Zero did not support that.)

On the Pi the RFM69 breadboard using the following Pins:

Vin to Raspberry Pi 3.3V
GND to Raspberry Pi Ground
RFM G0 to Raspberry Pi GPIO #24
RFM RST to Raspberry Pi GPIO #25
RFM CLK to Raspberry Pi SCLK = GPIO #11
RFM MISO to Raspberry Pi MISO = GPIO #9
RFM MOSI to Raspberry Pi MOSI = GPIO #10
RFM CS to Raspberry Pi CS1 = GPIO #7

It's a good idea to use a external antenna for better signal coverage here too.

At least, with a distance of 10 meters - through thick walls, plants and obstacles i got a RSSI of 65. (RFM69 transceiver power: 17, can be increased up to 20)

Against the default CPython RFM69 adafruit driver, I use DIO 0 interrupt to detect incoming data. See my project page on GitHub, how the bridge work. For the 433 MHz communication i use:

http://www.airspayce.com/mikem/arduino/RF69/

At least, the bridge log:

supplement:

Additionally, i transcode the javascript based FakegatoHistory into Python to get a history view in the fantastic eve-app:

Code

#include <Arduino.h>
#include <RH_RF69.h>
#include <RHDatagram.h>
#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>
#include <Adafruit_SHT31.h>
#include <RTCZero.h>


//use these Pins to switch a 2N222 Transistor
// the sensors might need more current the Pins itself can deliver
// the spec describe the max current per pin with 10 mA
// connect the Pins to the Transistor base,
// collector to ground,
// emitter to EN Pin
//this will turn off the voltage regulator and the 3V pin
#define BMEPOWER A1
#define SHTPOWER A3
// the VBATPIN to measure the battery voltage
#define VBATPIN A7
// Feather M0 w/Radio
#define RF69_FREQ 433.0
#define RFM69_CS      8
#define RFM69_INT     3
#define RFM69_RST     4
#define CLIENT_ADDRESS 12 // RHDatagram
#define SERVER_ADDRESS 1 // RHDatagram
 
Adafruit_SHT31 sht31 = Adafruit_SHT31();
Adafruit_BME280 bme;
// Singleton instance of the radio driver
RH_RF69 rf69(RFM69_CS, RFM69_INT);
RHDatagram manager(rf69, CLIENT_ADDRESS);

/* Create an rtc object */
RTCZero rtc;
const bool resetTime = true;
const uint8_t wait = 30;
const byte seconds = 00;
const byte minutes = 00;
const byte hours = 10;    
const byte day = 1;
const byte month = 1;
const byte year = 20;

int Voltage;
int AirHumidity;
int AirTemperature;
int AirPressure;
int SoilHumidity;

int ReadBattery() {
  digitalWrite(VBATPIN, HIGH);delay(50);
  float measuredvbat = analogRead(VBATPIN);
  digitalWrite(VBATPIN, LOW);
  measuredvbat *=2; // we divided by 2, so multiply back
  measuredvbat *=3.3; // Multiply by 3.3V, our reference voltage
  measuredvbat /= 1024; // convert to voltage
  if (measuredvbat>4.25f){measuredvbat=4.25f;}
  int result = roundf(100*measuredvbat/4.25f);
  return result; // value back in percent
 };

 void Values() { 
  digitalWrite(BMEPOWER,HIGH);
  digitalWrite(SHTPOWER,HIGH);delay(100);
  bme.begin(0x76); 
  AirTemperature = roundf(bme.readTemperature());
  AirHumidity = roundf(bme.readHumidity());
  AirPressure = roundf(bme.readPressure() / 100.0F); // hPa
  sht31.begin(0x44);
  sht31.heater(false);
  SoilHumidity = roundf(sht31.readHumidity());
  digitalWrite(SHTPOWER, LOW);
  digitalWrite(BMEPOWER, LOW);
 };

void setup() {
  pinMode(LED_BUILTIN, OUTPUT); digitalWrite(LED_BUILTIN, LOW); // LED off
  pinMode(BMEPOWER, OUTPUT);pinMode(SHTPOWER, OUTPUT);pinMode(RFM69_RST, OUTPUT);
  //Serial.begin(9600);
  //while (!Serial)  delay(10); 
  digitalWrite(RFM69_RST, HIGH); delay(10);
  digitalWrite(RFM69_RST, LOW); delay(10);
  if (!manager.init()) {
    //Serial.println("init failed"); 
    while (1);}
  // Defaults after init are 434.0MHz, modulation GFSK_Rb250Fd250,
  //  +13dbM (for low power module) and No encryption
  if (!rf69.setFrequency(RF69_FREQ)) { 
    //Serial.println("setFrequency failed"); 
    while (1);}
  // If you are using a high power RF69 eg RFM69HW, you *must* set a Tx power with the
  // ishighpowermodule flag set like this:
  rf69.setTxPower(18, true);  // range from 14-20 for power, 2nd arg must be true for 69HCW
  // The encryption key has to be the same as the one in the server
  uint8_t key[] = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
                    0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08};
  rf69.setEncryptionKey(key);
  rtc.begin(resetTime);
  rtc.setTime(hours, minutes, seconds);
  rtc.setDate(day, month, year);
};

void alarmMatch() {
  rtc.setTime(hours, minutes, seconds);
  rtc.setDate(day, month, year);
};

void loop()
{
Voltage = ReadBattery();
Values();
char rpacket[60]; // max packet length RFM69 60 Byte
// create JSON Form to easier produce on Server side
int n = sprintf(rpacket, "{'%d':{'B':%d,'AT':%d,'AH':%d,'AP':%d,'SH':%d}}", 
CLIENT_ADDRESS, Voltage, AirTemperature, AirHumidity, AirPressure, SoilHumidity);
//Serial.printf("[%s] is a string %d chars long\n",rpacket,n);
uint8_t radiopacket[n]; // reduce to the needed packet size 'n'
memcpy(radiopacket, (const char*)rpacket, sizeof(rpacket));
manager.sendto(radiopacket, sizeof(radiopacket), SERVER_ADDRESS);
delay(50);
rf69.sleep(); 
rtc.setAlarmMinutes(wait);
rtc.setAlarmSeconds(0);
rtc.enableAlarm(rtc.MATCH_MMSS);
rtc.attachInterrupt(alarmMatch);
rtc.standbyMode();
};

/*
  RTC library for Arduino Zero.
  Copyright (c) 2015 Arduino LLC. All right reserved.
  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.
  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.
  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/

#ifndef RTC_ZERO_H
#define RTC_ZERO_H

#include "Arduino.h"

typedef void(*voidFuncPtr)(void);

class RTCZero {
public:

  enum Alarm_Match: uint8_t // Should we have this enum or just use the identifiers from /component/rtc.h ?
  {
    MATCH_OFF          = RTC_MODE2_MASK_SEL_OFF_Val,          // Never
    MATCH_SS           = RTC_MODE2_MASK_SEL_SS_Val,           // Every Minute
    MATCH_MMSS         = RTC_MODE2_MASK_SEL_MMSS_Val,         // Every Hour
    MATCH_HHMMSS       = RTC_MODE2_MASK_SEL_HHMMSS_Val,       // Every Day
    MATCH_DHHMMSS      = RTC_MODE2_MASK_SEL_DDHHMMSS_Val,     // Every Month
    MATCH_MMDDHHMMSS   = RTC_MODE2_MASK_SEL_MMDDHHMMSS_Val,   // Every Year
    MATCH_YYMMDDHHMMSS = RTC_MODE2_MASK_SEL_YYMMDDHHMMSS_Val  // Once, on a specific date and a specific time
  };

  RTCZero();
  void begin(bool resetTime = false);

  void enableAlarm(Alarm_Match match);
  void disableAlarm();

  void attachInterrupt(voidFuncPtr callback);
  void detachInterrupt();
  
  void standbyMode();
  
  /* Get Functions */

  uint8_t getSeconds();
  uint8_t getMinutes();
  uint8_t getHours();
  
  uint8_t getDay();
  uint8_t getMonth();
  uint8_t getYear();
  
  uint8_t getAlarmSeconds();
  uint8_t getAlarmMinutes();
  uint8_t getAlarmHours();

  uint8_t getAlarmDay();
  uint8_t getAlarmMonth();
  uint8_t getAlarmYear();

  /* Set Functions */

  void setSeconds(uint8_t seconds);
  void setMinutes(uint8_t minutes);
  void setHours(uint8_t hours);
  void setTime(uint8_t hours, uint8_t minutes, uint8_t seconds);

  void setDay(uint8_t day);
  void setMonth(uint8_t month);
  void setYear(uint8_t year);
  void setDate(uint8_t day, uint8_t month, uint8_t year);

  void setAlarmSeconds(uint8_t seconds);
  void setAlarmMinutes(uint8_t minutes);
  void setAlarmHours(uint8_t hours);
  void setAlarmTime(uint8_t hours, uint8_t minutes, uint8_t seconds);

  void setAlarmDay(uint8_t day);
  void setAlarmMonth(uint8_t month);
  void setAlarmYear(uint8_t year);
  void setAlarmDate(uint8_t day, uint8_t month, uint8_t year);

  /* Epoch Functions */

  uint32_t getEpoch();
  uint32_t getY2kEpoch();
  void setEpoch(uint32_t ts);
  void setY2kEpoch(uint32_t ts);
  void setAlarmEpoch(uint32_t ts);

  bool isConfigured() {
    return _configured;
  }

private:
  bool _configured;

  //void config32kOSC(void);
  void configureClock(void);
  void RTCreadRequest();
  bool RTCisSyncing(void);
  void RTCdisable();
  void RTCenable();
  void RTCreset();
  void RTCresetRemove();
};
#endif // RTC_ZERO_H

/*
  RTC library for Arduino Zero.
  Copyright (c) 2015 Arduino LLC. All right reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/

#include <time.h>

#include "RTCZero.h"

#define EPOCH_TIME_OFF      946684800  // This is 1st January 2000, 00:00:00 in epoch time
#define EPOCH_TIME_YEAR_OFF 100        // years since 1900

// Default date & time after reset
#define DEFAULT_YEAR    2000    // 2000..2063
#define DEFAULT_MONTH   1       // 1..12
#define DEFAULT_DAY     1       // 1..31
#define DEFAULT_HOUR    0       // 1..23
#define DEFAULT_MINUTE  0       // 0..59
#define DEFAULT_SECOND  0       // 0..59

voidFuncPtr RTC_callBack = NULL;

RTCZero::RTCZero()
{
  _configured = false;
}

void RTCZero::begin(bool resetTime)
{
  uint16_t tmp_reg = 0;
  
  PM->APBAMASK.reg |= PM_APBAMASK_RTC; // turn on digital interface clock
  //config32kOSC();

  // If the RTC is in clock mode and the reset was
  // not due to POR or BOD, preserve the clock time
  // POR causes a reset anyway, BOD behaviour is?
  bool validTime = false;
  RTC_MODE2_CLOCK_Type oldTime;

  if ((!resetTime) && (PM->RCAUSE.reg & (PM_RCAUSE_SYST | PM_RCAUSE_WDT | PM_RCAUSE_EXT))) {
    if (RTC->MODE2.CTRL.reg & RTC_MODE2_CTRL_MODE_CLOCK) {
      validTime = true;
      oldTime.reg = RTC->MODE2.CLOCK.reg;
    }
  }

  // Setup clock GCLK2 with OSC32K divided by 32
  configureClock();

  RTCdisable();

  RTCreset();

  tmp_reg |= RTC_MODE2_CTRL_MODE_CLOCK; // set clock operating mode
  tmp_reg |= RTC_MODE2_CTRL_PRESCALER_DIV1024; // set prescaler to 1024 for MODE2
  tmp_reg &= ~RTC_MODE2_CTRL_MATCHCLR; // disable clear on match
  
  //According to the datasheet RTC_MODE2_CTRL_CLKREP = 0 for 24h
  tmp_reg &= ~RTC_MODE2_CTRL_CLKREP; // 24h time representation

  RTC->MODE2.READREQ.reg &= ~RTC_READREQ_RCONT; // disable continuously mode

  RTC->MODE2.CTRL.reg = tmp_reg;
  while (RTCisSyncing())
    ;

  NVIC_EnableIRQ(RTC_IRQn); // enable RTC interrupt 
  NVIC_SetPriority(RTC_IRQn, 0x00);

  RTC->MODE2.INTENSET.reg |= RTC_MODE2_INTENSET_ALARM0; // enable alarm interrupt
  RTC->MODE2.Mode2Alarm[0].MASK.bit.SEL = MATCH_OFF; // default alarm match is off (disabled)
  
  while (RTCisSyncing())
    ;

  RTCenable();
  RTCresetRemove();

  // If desired and valid, restore the time value, else use first valid time value
  if ((!resetTime) && (validTime) && (oldTime.reg != 0L)) {
    RTC->MODE2.CLOCK.reg = oldTime.reg;
  }
  else {
    RTC->MODE2.CLOCK.reg = RTC_MODE2_CLOCK_YEAR(DEFAULT_YEAR - 2000) | RTC_MODE2_CLOCK_MONTH(DEFAULT_MONTH) 
        | RTC_MODE2_CLOCK_DAY(DEFAULT_DAY) | RTC_MODE2_CLOCK_HOUR(DEFAULT_HOUR) 
        | RTC_MODE2_CLOCK_MINUTE(DEFAULT_MINUTE) | RTC_MODE2_CLOCK_SECOND(DEFAULT_SECOND);
  }
  while (RTCisSyncing())
    ;

  _configured = true;
}

void RTC_Handler(void)
{
  if (RTC_callBack != NULL) {
    RTC_callBack();
  }

  RTC->MODE2.INTFLAG.reg = RTC_MODE2_INTFLAG_ALARM0; // must clear flag at end
}

void RTCZero::enableAlarm(Alarm_Match match)
{
  if (_configured) {
    RTC->MODE2.Mode2Alarm[0].MASK.bit.SEL = match;
    while (RTCisSyncing())
      ;
  }
}

void RTCZero::disableAlarm()
{
  if (_configured) {
    RTC->MODE2.Mode2Alarm[0].MASK.bit.SEL = 0x00;
    while (RTCisSyncing())
      ;
  }
}

void RTCZero::attachInterrupt(voidFuncPtr callback)
{
  RTC_callBack = callback;
}

void RTCZero::detachInterrupt()
{
  RTC_callBack = NULL;
}

void RTCZero::standbyMode()
{
  // Entering standby mode when connected
  // via the native USB port causes issues.
  SysTick->CTRL &= ~SysTick_CTRL_TICKINT_Msk;
  SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk;
  __DSB();
  __WFI();
  SysTick->CTRL |= SysTick_CTRL_TICKINT_Msk;
}

/*
 * Get Functions
 */

uint8_t RTCZero::getSeconds()
{
  RTCreadRequest();
  return RTC->MODE2.CLOCK.bit.SECOND;
}

uint8_t RTCZero::getMinutes()
{
  RTCreadRequest();
  return RTC->MODE2.CLOCK.bit.MINUTE;
}

uint8_t RTCZero::getHours()
{
  RTCreadRequest();
  return RTC->MODE2.CLOCK.bit.HOUR;
}

uint8_t RTCZero::getDay()
{
  RTCreadRequest();
  return RTC->MODE2.CLOCK.bit.DAY;
}

uint8_t RTCZero::getMonth()
{
  RTCreadRequest();
  return RTC->MODE2.CLOCK.bit.MONTH;
}

uint8_t RTCZero::getYear()
{
  RTCreadRequest();
  return RTC->MODE2.CLOCK.bit.YEAR;
}

uint8_t RTCZero::getAlarmSeconds()
{
  return RTC->MODE2.Mode2Alarm[0].ALARM.bit.SECOND;
}

uint8_t RTCZero::getAlarmMinutes()
{
  return RTC->MODE2.Mode2Alarm[0].ALARM.bit.MINUTE;
}

uint8_t RTCZero::getAlarmHours()
{
  return RTC->MODE2.Mode2Alarm[0].ALARM.bit.HOUR;
}

uint8_t RTCZero::getAlarmDay()
{
  return RTC->MODE2.Mode2Alarm[0].ALARM.bit.DAY;
}

uint8_t RTCZero::getAlarmMonth()
{
  return RTC->MODE2.Mode2Alarm[0].ALARM.bit.MONTH;
}

uint8_t RTCZero::getAlarmYear()
{
  return RTC->MODE2.Mode2Alarm[0].ALARM.bit.YEAR;
}

/*
 * Set Functions
 */

void RTCZero::setSeconds(uint8_t seconds)
{
  if (_configured) {
    RTC->MODE2.CLOCK.bit.SECOND = seconds;
    while (RTCisSyncing())
      ;
  }
}

void RTCZero::setMinutes(uint8_t minutes)
{
  if (_configured) {
    RTC->MODE2.CLOCK.bit.MINUTE = minutes;
    while (RTCisSyncing())
      ;
  }
}

void RTCZero::setHours(uint8_t hours)
{
  if (_configured) {
    RTC->MODE2.CLOCK.bit.HOUR = hours;
    while (RTCisSyncing())
      ;
  }
}

void RTCZero::setTime(uint8_t hours, uint8_t minutes, uint8_t seconds)
{
  if (_configured) {
    setSeconds(seconds);
    setMinutes(minutes);
    setHours(hours);
  }
}

void RTCZero::setDay(uint8_t day)
{
  if (_configured) {
    RTC->MODE2.CLOCK.bit.DAY = day;
    while (RTCisSyncing())
      ;
  }
}

void RTCZero::setMonth(uint8_t month)
{
  if (_configured) {
    RTC->MODE2.CLOCK.bit.MONTH = month;
    while (RTCisSyncing())
      ;
  }
}

void RTCZero::setYear(uint8_t year)
{
  if (_configured) {
    RTC->MODE2.CLOCK.bit.YEAR = year;
    while (RTCisSyncing())
      ;
  }
}

void RTCZero::setDate(uint8_t day, uint8_t month, uint8_t year)
{
  if (_configured) {
    setDay(day);
    setMonth(month);
    setYear(year);
  }
}

void RTCZero::setAlarmSeconds(uint8_t seconds)
{
  if (_configured) {
    RTC->MODE2.Mode2Alarm[0].ALARM.bit.SECOND = seconds;
    while (RTCisSyncing())
      ;
  }
}

void RTCZero::setAlarmMinutes(uint8_t minutes)
{
  if (_configured) {
    RTC->MODE2.Mode2Alarm[0].ALARM.bit.MINUTE = minutes;
    while (RTCisSyncing())
      ;
  }
}

void RTCZero::setAlarmHours(uint8_t hours)
{
  if (_configured) {
    RTC->MODE2.Mode2Alarm[0].ALARM.bit.HOUR = hours;
    while (RTCisSyncing())
      ;
  }
}

void RTCZero::setAlarmTime(uint8_t hours, uint8_t minutes, uint8_t seconds)
{
  if (_configured) {
    setAlarmSeconds(seconds);
    setAlarmMinutes(minutes);
    setAlarmHours(hours);
  }
}

void RTCZero::setAlarmDay(uint8_t day)
{
  if (_configured) {
    RTC->MODE2.Mode2Alarm[0].ALARM.bit.DAY = day;
    while (RTCisSyncing())
      ;
  }
}

void RTCZero::setAlarmMonth(uint8_t month)
{
  if (_configured) {
    RTC->MODE2.Mode2Alarm[0].ALARM.bit.MONTH = month;
    while (RTCisSyncing())
      ;
  }
}

void RTCZero::setAlarmYear(uint8_t year)
{
  if (_configured) {
    RTC->MODE2.Mode2Alarm[0].ALARM.bit.YEAR = year;
    while (RTCisSyncing())
      ;
  }
}

void RTCZero::setAlarmDate(uint8_t day, uint8_t month, uint8_t year)
{
  if (_configured) {
    setAlarmDay(day);
    setAlarmMonth(month);
    setAlarmYear(year);
  }
}

uint32_t RTCZero::getEpoch()
{
  RTCreadRequest();
  RTC_MODE2_CLOCK_Type clockTime;
  clockTime.reg = RTC->MODE2.CLOCK.reg;

  struct tm tm;

  tm.tm_isdst = -1;
  tm.tm_yday = 0;
  tm.tm_wday = 0;
  tm.tm_year = clockTime.bit.YEAR + EPOCH_TIME_YEAR_OFF;
  tm.tm_mon = clockTime.bit.MONTH - 1;
  tm.tm_mday = clockTime.bit.DAY;
  tm.tm_hour = clockTime.bit.HOUR;
  tm.tm_min = clockTime.bit.MINUTE;
  tm.tm_sec = clockTime.bit.SECOND;

  return mktime(&tm);
}

uint32_t RTCZero::getY2kEpoch()
{
  return (getEpoch() - EPOCH_TIME_OFF);
}

void RTCZero::setAlarmEpoch(uint32_t ts)
{
  if (_configured) {
    if (ts < EPOCH_TIME_OFF) {
      ts = EPOCH_TIME_OFF;
    }

    time_t t = ts;
    struct tm* tmp = gmtime(&t);

    setAlarmDate(tmp->tm_mday, tmp->tm_mon + 1, tmp->tm_year - EPOCH_TIME_YEAR_OFF);
    setAlarmTime(tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
  }
}

void RTCZero::setEpoch(uint32_t ts)
{
  if (_configured) {
    if (ts < EPOCH_TIME_OFF) {
      ts = EPOCH_TIME_OFF;
    }

    time_t t = ts;
    struct tm* tmp = gmtime(&t);

    RTC_MODE2_CLOCK_Type clockTime;

    clockTime.bit.YEAR = tmp->tm_year - EPOCH_TIME_YEAR_OFF;
    clockTime.bit.MONTH = tmp->tm_mon + 1;
    clockTime.bit.DAY = tmp->tm_mday;
    clockTime.bit.HOUR = tmp->tm_hour;
    clockTime.bit.MINUTE = tmp->tm_min;
    clockTime.bit.SECOND = tmp->tm_sec;

    RTC->MODE2.CLOCK.reg = clockTime.reg;

    while (RTCisSyncing())
      ;
  }
}

void RTCZero::setY2kEpoch(uint32_t ts)
{
  if (_configured) {
    setEpoch(ts + EPOCH_TIME_OFF);
  }
}

/* Attach peripheral clock to 32k oscillator */
void RTCZero::configureClock() {
  GCLK->GENDIV.reg = GCLK_GENDIV_ID(2)|GCLK_GENDIV_DIV(4);
  while (GCLK->STATUS.reg & GCLK_STATUS_SYNCBUSY);
//#ifdef CRYSTALLESS 
  GCLK->GENCTRL.reg = (GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_OSCULP32K | GCLK_GENCTRL_ID(2) | GCLK_GENCTRL_DIVSEL );
//#else 
 // GCLK->GENCTRL.reg = (GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_XOSC32K | GCLK_GENCTRL_ID(2) | GCLK_GENCTRL_DIVSEL );
//#endif
  while (GCLK->STATUS.reg & GCLK_STATUS_SYNCBUSY);
  GCLK->CLKCTRL.reg = (uint32_t)((GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK2 | (RTC_GCLK_ID << GCLK_CLKCTRL_ID_Pos)));
  while (GCLK->STATUS.bit.SYNCBUSY)
    ;
}

/*
 * Private Utility Functions
 */

/* Configure the 32768Hz Oscillator */
void RTCZero::config32kOSC() 
{
  // GCLK_GENCTRL_SRC_OSCULP32K is always on!
  
  SYSCTRL->XOSC32K.reg = SYSCTRL_XOSC32K_ONDEMAND |
                          SYSCTRL_XOSC32K_RUNSTDBY |
                          SYSCTRL_XOSC32K_EN32K |
                          SYSCTRL_XOSC32K_XTALEN |
                          SYSCTRL_XOSC32K_STARTUP(6) |
                          SYSCTRL_XOSC32K_ENABLE;
};

/* Synchronise the CLOCK register for reading*/
inline void RTCZero::RTCreadRequest() {
  if (_configured) {
    RTC->MODE2.READREQ.reg = RTC_READREQ_RREQ;
    while (RTCisSyncing())
      ;
  }
}

/* Wait for sync in write operations */
inline bool RTCZero::RTCisSyncing()
{
  return (RTC->MODE2.STATUS.bit.SYNCBUSY);
}

void RTCZero::RTCdisable()
{
  RTC->MODE2.CTRL.reg &= ~RTC_MODE2_CTRL_ENABLE; // disable RTC
  while (RTCisSyncing())
    ;
}

void RTCZero::RTCenable()
{
  RTC->MODE2.CTRL.reg |= RTC_MODE2_CTRL_ENABLE; // enable RTC
  while (RTCisSyncing())
    ;
}

void RTCZero::RTCreset()
{
  RTC->MODE2.CTRL.reg |= RTC_MODE2_CTRL_SWRST; // software reset
  while (RTCisSyncing())
    ;
}

void RTCZero::RTCresetRemove()
{
  RTC->MODE2.CTRL.reg &= ~RTC_MODE2_CTRL_SWRST; // software reset remove
  while (RTCisSyncing())
    ;
}