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Merge pull request #25 from Lincoln-Agritech/master
Add support for ADC wakeup interrupt on SAMD21
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3 files changed

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Diff for: ‎examples/AdcWakeup/AdcWakeup.ino

+61
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,61 @@
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/*
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AdcWakeup
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This sketch demonstrates the usage of the ADC to wakeup a chip in sleep mode.
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Sleep modes allow a significant drop in the power usage of a board while it does nothing waiting for an event to happen. Battery powered application can take advantage of these modes to enhance battery life significantly.
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In this sketch, changing the voltage on pin A0 will wake up the board. You can test this by connecting a potentiometer between VCC, A0, and GND.
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Please note that, if the processor is sleeping, a new sketch can't be uploaded. To overcome this, manually reset the board (usually with a single or double tap to the RESET button)
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This example code is in the public domain.
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*/
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#include "ArduinoLowPower.h"
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// Blink sequence number
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// Declare it volatile since it's incremented inside an interrupt
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volatile int repetitions = 1;
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// Pin used to trigger a wakeup
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const int pin = A0;
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// How sensitive to be to changes in voltage
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const int margin = 10;
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void setup() {
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pinMode(LED_BUILTIN, OUTPUT);
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pinMode(pin, INPUT);
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}
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void loop() {
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for (int i = 0; i < repetitions; i++) {
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digitalWrite(LED_BUILTIN, HIGH);
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delay(500);
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digitalWrite(LED_BUILTIN, LOW);
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delay(500);
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}
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// Read the voltage at the ADC pin
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int value = analogRead(pin);
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// Define a window around that value
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uint16_t lo = max(value - margin, 0);
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uint16_t hi = min(value + margin, UINT16_MAX);
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// Attach an ADC interrupt on pin A0, calling repetitionsIncrease when the voltage is outside the given range.
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// This should be called immediately before LowPower.sleep() because it reconfigures the ADC internally.
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LowPower.attachAdcInterrupt(pin, repetitionsIncrease, ADC_INT_OUTSIDE, lo, hi);
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// Triggers an infinite sleep (the device will be woken up only by the registered wakeup sources)
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// The power consumption of the chip will drop consistently
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LowPower.sleep();
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// Detach the ADC interrupt. This should be called immediately after LowPower.sleep() because it restores the ADC configuration after waking up.
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LowPower.detachAdcInterrupt();
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}
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void repetitionsIncrease() {
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// This function will be called once on device wakeup
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// You can do some little operations here (like changing variables which will be used in the loop)
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// Remember to avoid calling delay() and long running functions since this functions executes in interrupt context
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repetitions ++;
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}

Diff for: ‎src/ArduinoLowPower.h

+17
Original file line numberDiff line numberDiff line change
@@ -28,6 +28,16 @@ typedef enum{
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ANALOG_COMPARATOR_WAKEUP = 3
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} wakeup_reason;
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#ifdef ARDUINO_ARCH_SAMD
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enum adc_interrupt
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{
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ADC_INT_BETWEEN,
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ADC_INT_OUTSIDE,
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ADC_INT_ABOVE_MIN,
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ADC_INT_BELOW_MAX,
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};
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#endif
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class ArduinoLowPowerClass {
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public:
@@ -68,10 +78,17 @@ class ArduinoLowPowerClass {
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wakeup_reason wakeupReason();
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#endif
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#ifdef ARDUINO_ARCH_SAMD
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void attachAdcInterrupt(uint32_t pin, voidFuncPtr callback, adc_interrupt mode, uint16_t lo, uint16_t hi);
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void detachAdcInterrupt();
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#endif
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private:
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void setAlarmIn(uint32_t millis);
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#ifdef ARDUINO_ARCH_SAMD
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RTCZero rtc;
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voidFuncPtr adc_cb;
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friend void ADC_Handler();
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#endif
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#ifdef BOARD_HAS_COMPANION_CHIP
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void (*companionSleepCB)(bool);

Diff for: ‎src/samd/ArduinoLowPower.cpp

+126-14
Original file line numberDiff line numberDiff line change
@@ -3,6 +3,27 @@
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#include "ArduinoLowPower.h"
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#include "WInterrupts.h"
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static void configGCLK6()
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{
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// enable EIC clock
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GCLK->CLKCTRL.bit.CLKEN = 0; //disable GCLK module
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while (GCLK->STATUS.bit.SYNCBUSY);
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GCLK->CLKCTRL.reg = (uint16_t) (GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK6 | GCLK_CLKCTRL_ID( GCM_EIC )) ; //EIC clock switched on GCLK6
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while (GCLK->STATUS.bit.SYNCBUSY);
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GCLK->GENCTRL.reg = (GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_OSCULP32K | GCLK_GENCTRL_ID(6)); //source for GCLK6 is OSCULP32K
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while (GCLK->STATUS.reg & GCLK_STATUS_SYNCBUSY);
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GCLK->GENCTRL.bit.RUNSTDBY = 1; //GCLK6 run standby
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while (GCLK->STATUS.reg & GCLK_STATUS_SYNCBUSY);
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/* Errata: Make sure that the Flash does not power all the way down
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* when in sleep mode. */
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NVMCTRL->CTRLB.bit.SLEEPPRM = NVMCTRL_CTRLB_SLEEPPRM_DISABLED_Val;
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}
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void ArduinoLowPowerClass::idle() {
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SCB->SCR &= ~SCB_SCR_SLEEPDEEP_Msk;
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PM->SLEEP.reg = 2;
@@ -80,26 +101,117 @@ void ArduinoLowPowerClass::attachInterruptWakeup(uint32_t pin, voidFuncPtr callb
80101
//pinMode(pin, INPUT_PULLUP);
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attachInterrupt(pin, callback, mode);
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// enable EIC clock
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GCLK->CLKCTRL.bit.CLKEN = 0; //disable GCLK module
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while (GCLK->STATUS.bit.SYNCBUSY);
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configGCLK6();
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GCLK->CLKCTRL.reg = (uint16_t) (GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK6 | GCLK_CLKCTRL_ID( GCM_EIC )) ; //EIC clock switched on GCLK6
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while (GCLK->STATUS.bit.SYNCBUSY);
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// Enable wakeup capability on pin in case being used during sleep
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EIC->WAKEUP.reg |= (1 << in);
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}
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GCLK->GENCTRL.reg = (GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_OSCULP32K | GCLK_GENCTRL_ID(6)); //source for GCLK6 is OSCULP32K
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while (GCLK->STATUS.reg & GCLK_STATUS_SYNCBUSY);
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void ArduinoLowPowerClass::attachAdcInterrupt(uint32_t pin, voidFuncPtr callback, adc_interrupt mode, uint16_t lo, uint16_t hi)
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{
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uint8_t winmode = 0;
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93-
GCLK->GENCTRL.bit.RUNSTDBY = 1; //GCLK6 run standby
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while (GCLK->STATUS.reg & GCLK_STATUS_SYNCBUSY);
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switch (mode) {
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case ADC_INT_BETWEEN: winmode = ADC_WINCTRL_WINMODE_MODE3; break;
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case ADC_INT_OUTSIDE: winmode = ADC_WINCTRL_WINMODE_MODE4; break;
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case ADC_INT_ABOVE_MIN: winmode = ADC_WINCTRL_WINMODE_MODE1; break;
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case ADC_INT_BELOW_MAX: winmode = ADC_WINCTRL_WINMODE_MODE2; break;
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default: return;
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}
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// Enable wakeup capability on pin in case being used during sleep
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EIC->WAKEUP.reg |= (1 << in);
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adc_cb = callback;
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/* Errata: Make sure that the Flash does not power all the way down
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* when in sleep mode. */
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configGCLK6();
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102-
NVMCTRL->CTRLB.bit.SLEEPPRM = NVMCTRL_CTRLB_SLEEPPRM_DISABLED_Val;
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// Configure ADC to use GCLK6 (OSCULP32K)
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while (GCLK->STATUS.bit.SYNCBUSY) {}
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GCLK->CLKCTRL.reg = GCLK_CLKCTRL_ID_ADC
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| GCLK_CLKCTRL_GEN_GCLK6
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| GCLK_CLKCTRL_CLKEN;
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while (GCLK->STATUS.bit.SYNCBUSY) {}
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// Set ADC prescaler as low as possible
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ADC->CTRLB.bit.PRESCALER = ADC_CTRLB_PRESCALER_DIV4;
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while (ADC->STATUS.bit.SYNCBUSY) {}
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// Configure window mode
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ADC->WINLT.reg = lo;
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ADC->WINUT.reg = hi;
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ADC->WINCTRL.reg = winmode;
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while (ADC->STATUS.bit.SYNCBUSY) {}
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// Enable window interrupt
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ADC->INTENSET.bit.WINMON = 1;
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while (ADC->STATUS.bit.SYNCBUSY) {}
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// Enable ADC in standby mode
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ADC->CTRLA.bit.RUNSTDBY = 1;
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while (ADC->STATUS.bit.SYNCBUSY) {}
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// Enable continuous conversions
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ADC->CTRLB.bit.FREERUN = 1;
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while (ADC->STATUS.bit.SYNCBUSY) {}
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// Configure input mux
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ADC->INPUTCTRL.bit.MUXPOS = g_APinDescription[pin].ulADCChannelNumber;
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while (ADC->STATUS.bit.SYNCBUSY) {}
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// Enable the ADC
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ADC->CTRLA.bit.ENABLE = 1;
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while (ADC->STATUS.bit.SYNCBUSY) {}
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// Start continuous conversions
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ADC->SWTRIG.bit.START = 1;
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while (ADC->STATUS.bit.SYNCBUSY) {}
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// Enable the ADC interrupt
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NVIC_EnableIRQ(ADC_IRQn);
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}
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void ArduinoLowPowerClass::detachAdcInterrupt()
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{
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// Disable the ADC interrupt
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NVIC_DisableIRQ(ADC_IRQn);
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// Disable the ADC
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ADC->CTRLA.bit.ENABLE = 0;
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while (ADC->STATUS.bit.SYNCBUSY) {}
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// Disable continuous conversions
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ADC->CTRLB.bit.FREERUN = 0;
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while (ADC->STATUS.bit.SYNCBUSY) {}
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// Disable ADC in standby mode
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ADC->CTRLA.bit.RUNSTDBY = 1;
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while (ADC->STATUS.bit.SYNCBUSY) {}
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// Disable window interrupt
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ADC->INTENCLR.bit.WINMON = 1;
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while (ADC->STATUS.bit.SYNCBUSY) {}
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// Disable window mode
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ADC->WINCTRL.reg = ADC_WINCTRL_WINMODE_DISABLE;
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while (ADC->STATUS.bit.SYNCBUSY) {}
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// Restore ADC prescaler
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ADC->CTRLB.bit.PRESCALER = ADC_CTRLB_PRESCALER_DIV512_Val;
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while (ADC->STATUS.bit.SYNCBUSY) {}
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// Restore ADC clock
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while (GCLK->STATUS.bit.SYNCBUSY) {}
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GCLK->CLKCTRL.reg = GCLK_CLKCTRL_ID_ADC
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| GCLK_CLKCTRL_GEN_GCLK0
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| GCLK_CLKCTRL_CLKEN;
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while (GCLK->STATUS.bit.SYNCBUSY) {}
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adc_cb = nullptr;
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}
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void ADC_Handler()
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{
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// Clear the interrupt flag
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ADC->INTFLAG.bit.WINMON = 1;
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LowPower.adc_cb();
103215
}
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ArduinoLowPowerClass LowPower;

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