Diff: Arduino-mbed-APIs/arduino-mbed.cpp

Revision:

71:7067e67902a8

Parent:

70:1d496aae2819

Child:

75:7330dd86cdea

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Arduino-mbed-APIs/arduino-mbed.cpp	Sun Jul 23 16:09:55 2017 +0200
@@ -0,0 +1,667 @@
+/*
+ * The file is Licensed under the Apache License, Version 2.0
+ * (c) 2017 Helmut Tschemernjak
+ * 30826 Garbsen (Hannover) Germany
+ */
+
+#ifdef ARDUINO
+
+using namespace std;
+
+#include "arduino-mbed.h"
+
+
+static void pinInt00(void);
+static void pinInt01(void);
+static void pinInt02(void);
+static void pinInt03(void);
+static void pinInt04(void);
+static void pinInt05(void);
+static void pinInt06(void);
+static void pinInt07(void);
+static void pinInt08(void);
+static void pinInt09(void);
+static void pinInt10(void);
+static void pinInt11(void);
+static void pinInt12(void);
+static void pinInt13(void);
+static void pinInt14(void);
+static void pinInt15(void);
+static void pinInt16(void);
+static void pinInt17(void);
+static void pinInt18(void);
+static void pinInt19(void);
+static void pinInt20(void);
+static void pinInt21(void);
+static void pinInt22(void);
+static void pinInt23(void);
+static void pinInt24(void);
+static void pinInt25(void);
+static void pinInt26(void);
+static void pinInt27(void);
+static void pinInt28(void);
+static void pinInt29(void);
+static void pinInt30(void);
+static void pinInt31(void);
+static void pinInt32(void);
+static void pinInt33(void);
+static void pinInt34(void);
+static void pinInt35(void);
+static void pinInt36(void);
+static void pinInt37(void);
+static void pinInt38(void);
+static void pinInt39(void);
+static void pinInt40(void);
+static void pinInt41(void);
+static void pinInt42(void);
+static void pinInt43(void);
+static void pinInt44(void);
+static void pinInt45(void);
+static void pinInt46(void);
+static void pinInt47(void);
+
+
+
+#define MAX_MCU_PINS	48
+class InterruptIn;
+struct intPtrTable {
+    void (*func)(void);
+    InterruptIn	*context;
+} intPtrTable[MAX_MCU_PINS]  = {
+    { pinInt00, NULL },
+    { pinInt01, NULL },
+    { pinInt02, NULL },
+    { pinInt03, NULL },
+    { pinInt04, NULL },
+    { pinInt05, NULL },
+    { pinInt06, NULL },
+    { pinInt07, NULL },
+    { pinInt08, NULL },
+    { pinInt09, NULL },
+    { pinInt10, NULL },
+    { pinInt11, NULL },
+    { pinInt12, NULL },
+    { pinInt13, NULL },
+    { pinInt14, NULL },
+    { pinInt15, NULL },
+    { pinInt16, NULL },
+    { pinInt17, NULL },
+    { pinInt18, NULL },
+    { pinInt19, NULL },
+    { pinInt20, NULL },
+    { pinInt21, NULL },
+    { pinInt22, NULL },
+    { pinInt23, NULL },
+    { pinInt24, NULL },
+    { pinInt25, NULL },
+    { pinInt26, NULL },
+    { pinInt27, NULL },
+    { pinInt28, NULL },
+    { pinInt29, NULL },
+    { pinInt30, NULL },
+    { pinInt31, NULL },
+    { pinInt32, NULL },
+    { pinInt33, NULL },
+    { pinInt34, NULL },
+    { pinInt35, NULL },
+    { pinInt36, NULL },
+    { pinInt37, NULL },
+    { pinInt38, NULL },
+    { pinInt39, NULL },
+    { pinInt40, NULL },
+    { pinInt41, NULL },
+    { pinInt42, NULL },
+    { pinInt43, NULL },
+    { pinInt44, NULL },
+    { pinInt45, NULL },
+    { pinInt46, NULL },
+    { pinInt47, NULL }
+}; // our max MCUs pins
+
+
+
+static void pinInt00(void) { InterruptIn::_irq_handler(intPtrTable[0].context); }
+static void pinInt01(void) { InterruptIn::_irq_handler(intPtrTable[1].context); }
+static void pinInt02(void) { InterruptIn::_irq_handler(intPtrTable[2].context); }
+static void pinInt03(void) { InterruptIn::_irq_handler(intPtrTable[3].context); }
+static void pinInt04(void) { InterruptIn::_irq_handler(intPtrTable[4].context); }
+static void pinInt05(void) { InterruptIn::_irq_handler(intPtrTable[5].context); }
+static void pinInt06(void) { InterruptIn::_irq_handler(intPtrTable[6].context); }
+static void pinInt07(void) { InterruptIn::_irq_handler(intPtrTable[7].context); }
+static void pinInt08(void) { InterruptIn::_irq_handler(intPtrTable[8].context); }
+static void pinInt09(void) { InterruptIn::_irq_handler(intPtrTable[9].context); }
+static void pinInt10(void) { InterruptIn::_irq_handler(intPtrTable[10].context); }
+static void pinInt11(void) { InterruptIn::_irq_handler(intPtrTable[11].context); }
+static void pinInt12(void) { InterruptIn::_irq_handler(intPtrTable[12].context); }
+static void pinInt13(void) { InterruptIn::_irq_handler(intPtrTable[13].context); }
+static void pinInt14(void) { InterruptIn::_irq_handler(intPtrTable[14].context); }
+static void pinInt15(void) { InterruptIn::_irq_handler(intPtrTable[15].context); }
+static void pinInt16(void) { InterruptIn::_irq_handler(intPtrTable[16].context); }
+static void pinInt17(void) { InterruptIn::_irq_handler(intPtrTable[17].context); }
+static void pinInt18(void) { InterruptIn::_irq_handler(intPtrTable[18].context); }
+static void pinInt19(void) { InterruptIn::_irq_handler(intPtrTable[19].context); }
+static void pinInt20(void) { InterruptIn::_irq_handler(intPtrTable[20].context); }
+static void pinInt21(void) { InterruptIn::_irq_handler(intPtrTable[21].context); }
+static void pinInt22(void) { InterruptIn::_irq_handler(intPtrTable[22].context); }
+static void pinInt23(void) { InterruptIn::_irq_handler(intPtrTable[23].context); }
+static void pinInt24(void) { InterruptIn::_irq_handler(intPtrTable[24].context); }
+static void pinInt25(void) { InterruptIn::_irq_handler(intPtrTable[25].context); }
+static void pinInt26(void) { InterruptIn::_irq_handler(intPtrTable[26].context); }
+static void pinInt27(void) { InterruptIn::_irq_handler(intPtrTable[27].context); }
+static void pinInt28(void) { InterruptIn::_irq_handler(intPtrTable[28].context); }
+static void pinInt29(void) { InterruptIn::_irq_handler(intPtrTable[29].context); }
+static void pinInt30(void) { InterruptIn::_irq_handler(intPtrTable[30].context); }
+static void pinInt31(void) { InterruptIn::_irq_handler(intPtrTable[31].context); }
+static void pinInt32(void) { InterruptIn::_irq_handler(intPtrTable[32].context); }
+static void pinInt33(void) { InterruptIn::_irq_handler(intPtrTable[33].context); }
+static void pinInt34(void) { InterruptIn::_irq_handler(intPtrTable[34].context); }
+static void pinInt35(void) { InterruptIn::_irq_handler(intPtrTable[35].context); }
+static void pinInt36(void) { InterruptIn::_irq_handler(intPtrTable[36].context); }
+static void pinInt37(void) { InterruptIn::_irq_handler(intPtrTable[37].context); }
+static void pinInt38(void) { InterruptIn::_irq_handler(intPtrTable[38].context); }
+static void pinInt39(void) { InterruptIn::_irq_handler(intPtrTable[39].context); }
+static void pinInt40(void) { InterruptIn::_irq_handler(intPtrTable[40].context); }
+static void pinInt41(void) { InterruptIn::_irq_handler(intPtrTable[41].context); }
+static void pinInt42(void) { InterruptIn::_irq_handler(intPtrTable[42].context); }
+static void pinInt43(void) { InterruptIn::_irq_handler(intPtrTable[43].context); }
+static void pinInt44(void) { InterruptIn::_irq_handler(intPtrTable[44].context); }
+static void pinInt45(void) { InterruptIn::_irq_handler(intPtrTable[45].context); }
+static void pinInt46(void) { InterruptIn::_irq_handler(intPtrTable[46].context); }
+static void pinInt47(void) { InterruptIn::_irq_handler(intPtrTable[47].context); }
+
+
+
+
+void
+InterruptIn::rise(Callback<void()> func) {
+    if (_gpioPin >= MAX_MCU_PINS-1)
+        return;
+    if (func) {
+        _func = func;
+        intPtrTable[_gpioPin].context = this;
+        attachInterrupt(MYdigitalPinToInterrupt(_gpioPin), intPtrTable[_gpioPin].func, RISING);
+    } else {
+        _func = InterruptIn::donothing;
+        intPtrTable[_gpioPin].context = NULL;
+        detachInterrupt(_gpioPin);
+    }
+};
+
+void
+InterruptIn::fall(Callback<void()> func) {
+    if (func) {
+        _func = func;
+        intPtrTable[_gpioPin].context = this;
+        attachInterrupt(MYdigitalPinToInterrupt(_gpioPin), intPtrTable[_gpioPin].func, FALLING);
+    } else {
+        _func = InterruptIn::donothing;
+        intPtrTable[_gpioPin].context = NULL;
+        detachInterrupt(_gpioPin);
+    }
+}
+
+
+#define MAX_TIMEOUTS	10
+class Timeout;
+struct TimeoutVector {
+    Timeout *timer;
+} TimeOuts[MAX_TIMEOUTS];
+
+
+#if defined(__SAMD21G18A__) || defined(__SAMD21J18A__)
+/*
+ * __SAMD21J18A__ is the SamD21 Explained Board
+ * __SAMD21G18A__ is Genuino Zero-Board (compatible with the LoRa board)
+ */
+
+/*
+ * see tcc.h is automatically included from:
+ * Arduino15/packages/arduino/tools/CMSIS-Atmel/1.1.0/CMSIS/
+ * Device/ATMEL/samd21/include/component/tcc.h
+ * See also tcc.c (ASF/mbed, e.g. Tcc_get_count_value)
+ */
+static void initTimer(Tcc *t);
+static uint32_t getTimerCount(Tcc *t);
+
+/*
+ * The Atmel D21 has three TCC timer, other models have more.
+ */
+static const struct TCC_config {
+    Tcc *tcc_ptr;
+    IRQn_Type tcc_irq;
+    uint8_t nbits;
+} TCC_data[] {
+    { TCC0, TCC0_IRQn, 24 },
+    { TCC1, TCC1_IRQn, 24 },
+    { TCC2, TCC2_IRQn, 16 },
+    { NULL, (IRQn_Type)NULL, 0 }
+};
+
+/*
+ * We preferably use the TCC timers because it supports 24-bit counters
+ * versus TC Timer which supports only 8 or 16 bit counters
+ * TCC0/1/2 timer work on the D21 using Arduino.
+ */
+#define USE_TCC_TIMEOUT	0 // 0=TCC0, 1=TTC1, 2=TTC2 (see TCC_data)
+#define USE_TCC_TICKER	1
+
+
+/*
+ * every 21333 ns equals one tick (1/(48000000/1024)) // prescaler 1024, 48 MHz
+ * every 61035 ns equals one tick (1/(32768/2))		  // prescaler 2, 32 kHz
+ * COUNT*DIVIDER*SECS until interrupt
+ * CPU 48 MHz = (65536*1024)/1.398636s
+ * RTC 32 kHz = (65536*2)/4.0s
+ */
+#define NS_PER_CLOCK_CPU	21333 // ns secs per clock
+#define NS_PER_CLOCK_RTC	61035 // ns secs per clock
+
+#define NS_PER_CLOCK	NS_PER_CLOCK_RTC
+
+/* ----------------- TICKER TIMER CODE ----------------------*/
+
+/*
+ * The global ns_counter contains the time in ns from the last time
+ * the counter has been wrapped. It cannot be used directly because the
+ * current counter has to be added fore using it. Use instead
+ * ns_getTicker(), us_ ns_getTicker(), ms_getTicker()
+ */
+
+uint64_t ticker_ns;
+static bool initTickerDone = false;
+
+uint32_t s_getTicker(void)
+{
+    long long ns = ns_getTicker();
+    ns /= (long long)1000000000; // to secs
+    
+    int secs = ns;
+    return secs;
+}
+
+
+uint32_t ms_getTicker(void)
+{
+    uint32_t us = us_getTicker();
+    
+    us /= 1000; // to ms
+    return us;
+}
+
+uint32_t us_getTicker(void)
+{
+    long long ns = ns_getTicker();
+
+    ns /= (long long)1000; // to us
+    uint32_t us = ns & 0xffffffff;
+    
+    return us;
+}
+
+
+uint64_t ns_getTicker(void)
+{
+    Tcc *t = TCC_data[USE_TCC_TICKER].tcc_ptr;
+    if (!initTickerDone) {
+        initTimer(t);
+        initTickerDone = true;
+
+        // set counter top to max 16 bit for testing
+        // t->PER.bit.PER = 0xffff;
+        // while (t->SYNCBUSY.bit.PER == 1); // wait for sync
+
+        t->CTRLA.reg |= TCC_CTRLA_ENABLE ;		// Enable TC
+        while (t->SYNCBUSY.bit.ENABLE == 1);	// wait for sync
+    }
+    
+    /*
+     * if we are called from the interrupt level, the counter contains
+     * somehow wrong data, therfore we needs to read it twice.
+     * Another option was to add a little wait (loop 500x) 
+     * in the TCC_TIMEOUT interrupt handler.
+     */
+    if (SCB->ICSR & SCB_ICSR_VECTACTIVE_Msk) // check if we are in the interrupt
+        getTimerCount(t);
+
+    uint64_t counter_us = (uint64_t)NS_PER_CLOCK * (uint64_t)getTimerCount(t);
+    uint64_t ns = ticker_ns + counter_us;
+
+    return ns;
+}
+
+#if USE_TCC_TICKER == 0
+void TCC0_Handler()
+#elif USE_TCC_TICKER == 1
+void TCC1_Handler()
+#elif USE_TCC_TICKER == 2
+void TCC2_Handler()
+#endif
+{
+    Tcc *t = TCC_data[USE_TCC_TICKER].tcc_ptr;
+    /*
+     * Overflow means the timer top exeeded
+     */
+    if (t->INTFLAG.bit.OVF == 1) {  // A overflow caused the interrupt
+        t->INTFLAG.bit.OVF = 1;    // writing a one clears the flag ovf flag
+        // Serial.println("T_OVF");
+
+        /*
+         * reading the count once is needed, otherwise
+         * it will not wrap correct.
+         */
+        getTimerCount(t);
+        
+        int bits = TCC_data[USE_TCC_TICKER].nbits;
+        int maxCounts = (uint32_t)(1<<bits);
+		
+        ticker_ns += (uint64_t)NS_PER_CLOCK * (uint64_t)maxCounts;
+    }
+    if (t->INTFLAG.bit.MC0 == 1) {  // A compare to cc0 caused the interrupt
+        t->INTFLAG.bit.MC0 = 1;    // writing a one clears the MCO (match capture) flag
+        // Serial.println("T_MC0");
+    }
+}
+
+/* ----------------- SUPPORT CODE FOR TCC TIMERS----------------------*/
+
+static bool initTimerDone = false;
+
+static void initTimer(Tcc *t)
+{
+    
+    /*
+     * enable clock for TCC, see gclk.h
+     * GCLK_CLKCTRL_GEN_GCLK0 for 48 Mhz CPU
+     * GCLK_CLKCTRL_GEN_GCLK1 for 32k extern crystal XOSC32K (ifdef CRYSTALLESS)
+     * GCLK_CLKCTRL_GEN_GCLK1 for 32k internal OSC32K
+     * see Arduino: arduino/hardware/samd/1.6.15/cores/arduino/startup.c
+     * Use TCC_CTRLA_PRESCALER_DIV1024 for for 48 Mhz clock
+     * Use TCC_CTRLA_PRESCALER_DIV2 for 32k clock
+     */
+    if (t == TCC0 || t == TCC1) {
+        REG_GCLK_CLKCTRL = (uint16_t) (GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK1 | GCLK_CLKCTRL_ID_TCC0_TCC1);
+    } else if (t == TCC2) {
+        REG_GCLK_CLKCTRL = (uint16_t) (GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK1 | GCLK_CLKCTRL_ID_TCC2_TC3_Val);
+    }
+    while (GCLK->STATUS.bit.SYNCBUSY == 1); // wait for sync
+    
+    t->CTRLA.reg &= ~TCC_CTRLA_ENABLE;   // Disable TCC
+    while (t->SYNCBUSY.bit.ENABLE == 1); // wait for sync
+    
+    t->CTRLA.reg |= (TCC_CTRLA_PRESCALER_DIV2 | TCC_CTRLA_RUNSTDBY); // Set perscaler
+    
+    t->WAVE.reg |= TCC_WAVE_WAVEGEN_NFRQ; // Set wave form configuration
+    while (t->SYNCBUSY.bit.WAVE == 1);	   // wait for sync
+    
+    t->PER.bit.PER = 0xffffff; // set counter top to max 24 bit
+    while (t->SYNCBUSY.bit.PER == 1); // wait for sync
+    
+    // the compare counter TC->CC[0].reg will be set in the startTimer
+    // after the timeout calculation is known.
+    
+    // Interrupts
+    t->INTENSET.reg = 0;              // disable all interrupts
+    t->INTENSET.bit.OVF = 1;          // enable overfollow
+    t->INTENSET.bit.MC0 = 1;          // enable compare match to CC0
+    
+    const struct TCC_config *cp = &TCC_data[0];
+    while (cp->tcc_ptr) {
+        if (cp->tcc_ptr == t) {
+            NVIC_EnableIRQ(cp->tcc_irq); // Enable InterruptVector
+            break;
+        }
+        cp++;
+    }
+}
+
+#if 0
+// Atmel ASF Code
+static uint32_t getTimerCount(Tcc *t)
+{
+    uint32_t last_cmd;
+    /* Wait last command done */
+    do {
+        while (t->SYNCBUSY.bit.CTRLB); /* Wait for sync */
+        
+        last_cmd = t->CTRLBSET.reg & TCC_CTRLBSET_CMD_Msk;
+        if (TCC_CTRLBSET_CMD_NONE == last_cmd) {
+            /* Issue read command and break */
+            t->CTRLBSET.bit.CMD = TCC_CTRLBSET_CMD_READSYNC_Val;
+            break;
+        } else if (TCC_CTRLBSET_CMD_READSYNC == last_cmd) {
+            /* Command have been issued */
+            break;
+        }
+    } while (1);
+    
+    while (t->SYNCBUSY.bit.COUNT); /* Wait for sync */
+
+    return t->COUNT.reg;
+}
+#endif
+
+
+static uint32_t getTimerCount(Tcc *t)
+{
+    
+    noInterrupts();
+
+    while (t->SYNCBUSY.bit.CTRLB); /* Wait for sync */
+
+    t->CTRLBSET.bit.CMD = TCC_CTRLBSET_CMD_READSYNC_Val; /* Issue read command and break */
+
+    while (t->SYNCBUSY.bit.COUNT); /* Wait for sync */
+    
+    uint32_t count = t->COUNT.reg;
+
+    interrupts();
+    
+    return count;
+}
+
+
+static void stopTimer(Tcc *t)
+{
+    t->CTRLA.reg &= ~TCC_CTRLA_ENABLE;   // Disable TC
+    while (t->SYNCBUSY.bit.ENABLE == 1); // wait for sync
+}
+
+
+/* ----------------- TIMEOUT TIMER CODE ----------------------*/
+
+static void startTimer(Tcc *t, uint64_t delay_ns)
+{
+    if (!initTimerDone) {
+        initTimer(t);	// initial setup with stopped timer
+        initTimerDone = true;
+    }
+    
+    stopTimer(t);		// avoid timer interrupts while calculating
+    
+    /*
+     * every 21333 ns equals one tick (1/(48000000/1024))
+     * COUNT*DIVIDER*SECS until interrupt
+     * 48 Mhz = (65536*1024)/1.398636s
+     */
+    uint64_t nclocks = (uint64_t)delay_ns;
+    nclocks /= (uint64_t)NS_PER_CLOCK;
+    int nCounts = nclocks;
+   
+    int bits = TCC_data[USE_TCC_TIMEOUT].nbits;
+    int maxCounts = (uint32_t)(1<<bits)-1;
+
+    if (nCounts > maxCounts) 	// if count exceeds timer capacity
+        nCounts =  maxCounts;	// set the largest posible count.
+    if (nCounts <= 0)
+        nCounts = 1;
+    t->CC[0].bit.CC = nCounts;
+    while (t->SYNCBUSY.bit.CC0 == 1); // wait for sync
+
+    t->CTRLA.reg |= TCC_CTRLA_ENABLE ; // Enable TC
+    while (t->SYNCBUSY.bit.ENABLE == 1); // wait for sync
+#if 0
+    Serial.print(ms_getTicker(), DEC);
+    Serial.print(" startTimer: nCounts=");
+    Serial.println(nCounts, DEC);
+#endif
+}
+
+
+#if USE_TCC_TIMEOUT == 0
+void TCC0_Handler()
+#elif USE_TCC_TIMEOUT == 1
+void TCC1_Handler()
+#elif USE_TCC_TIMEOUT == 2
+void TCC2_Handler()
+#endif
+{
+    Tcc *t = TCC_data[USE_TCC_TIMEOUT].tcc_ptr;
+    uint64_t nsecs = ns_getTicker();
+    
+    /*
+     * Overflow means the max timer exeeded, we need restart the timer
+     * Interrupts and
+     */
+    if (t->INTFLAG.bit.OVF == 1) {  // A overflow caused the interrupt
+        t->INTFLAG.bit.OVF = 1;    // writing a one clears the flag ovf flag
+    }
+    
+    if (t->INTFLAG.bit.MC0 == 1) {  // A compare to cc0 caused the interrupt
+        //Serial.print("MC0\r\n");
+        t->INTFLAG.bit.MC0 = 1;    // writing a one clears the MCO (match capture) flag
+    }
+
+    t->CTRLA.reg &= ~TCC_CTRLA_ENABLE;   // Disable TC
+    while (t->SYNCBUSY.bit.ENABLE == 1); // wait for sync
+    
+    for (int i = 0; i < MAX_TIMEOUTS-1; i++) {
+        struct TimeoutVector *tvp = &TimeOuts[i];
+        if (tvp->timer && nsecs >= tvp->timer->_timeout) {
+            Timeout *saveTimer = tvp->timer;
+            tvp->timer = NULL;
+            Timeout::_irq_handler(saveTimer);
+        }
+    }
+    /*
+     * we need to restart the timer for remaining interrupts
+     * Another reason is that we stopped this counter, in case there are
+     * remaining counts, we need to re-schedule the counter.
+     */
+	Timeout::restart();
+}
+
+
+#endif // D21 TCC Timer
+
+void
+Timeout::insert(void)
+{
+    noInterrupts();
+    for (int i = 0; i < MAX_TIMEOUTS-1; i++) {
+        struct TimeoutVector *tvp = &TimeOuts[i];
+        if (tvp->timer == NULL) {
+            tvp->timer = this;
+            break;
+        }
+    }
+    interrupts();
+}
+
+void
+Timeout::remove(void)
+{
+    noInterrupts();
+    for (int i = 0; i < MAX_TIMEOUTS-1; i++) {
+        struct TimeoutVector *tvp = &TimeOuts[i];
+        if (tvp->timer == this) {
+            tvp->timer = NULL;
+            break;
+        }
+    }
+    interrupts();
+}
+
+
+void
+Timeout::restart()
+{
+    Tcc *t = TCC_data[USE_TCC_TIMEOUT].tcc_ptr;
+    uint64_t timeout = ~0;
+    
+    /*
+     * find the lowest timeout value which is our the next timeout
+     * zero means stop the timer.
+     */
+    noInterrupts();
+    for (int i = 0; i < MAX_TIMEOUTS-1; i++) {
+        struct TimeoutVector *tvp = &TimeOuts[i];
+        if (tvp->timer) {
+            if (tvp->timer->_timeout < timeout) {
+                timeout = tvp->timer->_timeout;
+            }
+        }
+    }
+    interrupts();
+    
+    if (timeout == (uint64_t)~0) {
+        stopTimer(t);
+        return;
+    }
+    
+    uint64_t nsecs = ns_getTicker();
+    
+    if (timeout > nsecs) {
+        startTimer(t, (uint64_t)timeout - (uint64_t)nsecs);
+        return;
+    } else {
+        startTimer(t, (uint64_t)1); // just one nsec to trigger interrrupt
+    }
+}
+
+/* ----------------- D21 sleep() and deepsleep() code ----------------------*/
+
+void sleep(void)
+{
+#if  1 // (SAMD20 || SAMD21)
+    /* Errata: Make sure that the Flash does not power all the way down
+     * when in sleep mode. */
+    NVMCTRL->CTRLB.bit.SLEEPPRM = NVMCTRL_CTRLB_SLEEPPRM_DISABLED_Val;
+#endif
+    uint32_t saved_ms = ms_getTicker();
+    SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk; // disbale SysTick
+    
+    SCB->SCR &= ~SCB_SCR_SLEEPDEEP_Msk;	// clear deep sleep
+    PM->SLEEP.reg = 2; // SYSTEM_SLEEPMODE_IDLE_2 IDLE 2 sleep mode.
+
+    __DSB(); // ensures the completion of memory accesses
+    __WFI(); // wait for interrupt
+    
+    int count = ms_getTicker() - saved_ms;
+    if (count > 0) { // update the Arduino Systicks
+        for (int i = 0; i < count; i++) {
+            SysTick_Handler();
+        }
+    }
+    SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk; // enable SysTick
+}
+
+void deepsleep(void)
+{
+#if  1 // (SAMD20 || SAMD21)
+    /* Errata: Make sure that the Flash does not power all the way down
+     * when in sleep mode. */
+    NVMCTRL->CTRLB.bit.SLEEPPRM = NVMCTRL_CTRLB_SLEEPPRM_DISABLED_Val;
+#endif
+
+    SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk; // disbale SysTick
+    
+    SCB->SCR |=  SCB_SCR_SLEEPDEEP_Msk; // standby mode
+    
+    __DSB(); // ensures the completion of memory accesses
+    __WFI(); // wait for interrupt
+
+    SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk; // enable SysTick
+}
+
+
+#endif // ARDUINO