Fix watchdog sleep calculation (#814)

Round requested sleep time up to next multiple of 16ms, to sleep at
least requested time.
Sleep time of 0 will return immediately.
Fixed watchdog sleep time calculation. AVR libc watchdog time
implementation is inconsistent, and requires larger flash/ram usage.

core/MyHwAVR.cpp

@@ -27,7 +27,7 @@ bool hwInit(void)
 	return true;
 }
 
-
+#define WDTO_SLEEP_FOREVER      (0xFFu)
 #define INVALID_INTERRUPT_NUM	(0xFFu)
 
 volatile uint8_t _wokeUpByInterrupt =
@@ -72,14 +72,19 @@ ISR (WDT_vect)
 {
 }
 
-void hwPowerDown(period_t period)
+void hwPowerDown(const uint8_t wdto)
 {
+	// Let serial prints finish (debug, log etc)
+#ifndef MY_DISABLED_SERIAL
+	MY_SERIALDEVICE.flush();
+#endif
+
 	// disable ADC for power saving
 	ADCSRA &= ~(1 << ADEN);
 	// save WDT settings
 	uint8_t WDTsave = WDTCSR;
-	if (period != SLEEP_FOREVER) {
+	if (wdto != WDTO_SLEEP_FOREVER) {
-		wdt_enable(period);
+		wdt_enable(wdto);
 		// enable WDT interrupt before system reset
 		WDTCSR |= (1 << WDCE) | (1 << WDIE);
 	} else {
@@ -112,33 +117,19 @@ void hwPowerDown(period_t period)
 
 void hwInternalSleep(unsigned long ms)
 {
-	// Let serial prints finish (debug, log etc)
+	// Sleeping with watchdog only supports multiples of 16ms.
-#ifndef MY_DISABLED_SERIAL
+	// Round up to next multiple of 16ms, to assure we sleep at least the
-	MY_SERIALDEVICE.flush();
+	// requested amount of time. Sleep of 0ms will not sleep at all!
-#endif
+	ms += 15u;
 
-    static const struct {
+	while (!interruptWakeUp() && ms >= 16) {
-        uint16_t ms;
+		for (uint8_t period = 9u; ;--period) {
-        period_t period;
+			const uint16_t comparatorMS = 1 << (period + 4);
-    } wdtTimes[] = {
+			if ( ms >= comparatorMS) {
-        { 8000u, SLEEP_8S    },
+				hwPowerDown(period); // 8192ms => 9, 16ms => 0
-        { 4000u, SLEEP_4S    },
+				ms -= comparatorMS;
-        { 2000u, SLEEP_2S    },
+				break;
-        { 1000u, SLEEP_1S    },
+			}
-        {  500u, SLEEP_500MS },
-        {  250u, SLEEP_250MS },
-        {  120u, SLEEP_120MS },
-        {   60u, SLEEP_60MS  },
-        {   30u, SLEEP_30MS  },
-        {   15u, SLEEP_15MS  },
-    };
-
-    for (size_t i = 0; i < sizeof(wdtTimes)/sizeof(wdtTimes[0]); ++i)
-    {
-        while (ms >= wdtTimes[i].ms && !interruptWakeUp() )
-        {
-            hwPowerDown(wdtTimes[i].period);
-            ms -= wdtTimes[i].ms;
 		}
 	}
 }
@@ -180,12 +171,12 @@ int8_t hwSleep(uint8_t interrupt1, uint8_t mode1, uint8_t interrupt2, uint8_t mo
 		attachInterrupt(interrupt2, wakeUp2, mode2);
 	}
 
-	if (ms>0) {
+	if (ms > 0u) {
 		// sleep for defined time
 		hwInternalSleep(ms);
 	} else {
 		// sleep until ext interrupt triggered
-		hwPowerDown(SLEEP_FOREVER);
+		hwPowerDown(WDTO_SLEEP_FOREVER);
 	}
 
 	// Assure any interrupts attached, will get detached when they did not occur.
@@ -277,8 +268,8 @@ void hwDebugPrint(const char *fmt, ... )
 	char fmtBuffer[MY_SERIAL_OUTPUT_SIZE];
 #ifdef MY_GATEWAY_FEATURE
 	// prepend debug message to be handled correctly by controller (C_INTERNAL, I_LOG_MESSAGE)
-	snprintf_P(fmtBuffer, sizeof(fmtBuffer), PSTR("0;255;%d;0;%d;%lu "), C_INTERNAL, I_LOG_MESSAGE,
+	snprintf_P(fmtBuffer, sizeof(fmtBuffer), PSTR("0;255;%d;0;%d;%lu "),
-	           hwMillis());
+				C_INTERNAL, I_LOG_MESSAGE, hwMillis());
 	MY_SERIALDEVICE.print(fmtBuffer);
 #else
 	// prepend timestamp

core/MyHwAVR.h

@@ -54,20 +54,6 @@ bool hwInit(void);
 #define hwReadConfigBlock(__buf, __pos, __length) eeprom_read_block((void*)(__buf), (void*)(__pos), (__length))
 #define hwWriteConfigBlock(__buf, __pos, __length) eeprom_update_block((void*)(__buf), (void*)(__pos), (__length))
 
-enum period_t {
-	SLEEP_15MS,
-	SLEEP_30MS,
-	SLEEP_60MS,
-	SLEEP_120MS,
-	SLEEP_250MS,
-	SLEEP_500MS,
-	SLEEP_1S,
-	SLEEP_2S,
-	SLEEP_4S,
-	SLEEP_8S,
-	SLEEP_FOREVER
-};
-
 void hwInternalSleep(unsigned long ms);
 
 #ifndef DOXYGEN