Fix SysTick timer lockup when waking from sleep (#17)

sslupsky · facchinm · commit 892594adbccf · 2019-05-14T09:56:55.000+02:00
* fix SysTick timer lockup when waking from sleep
diff --git a/src/samd/ArduinoLowPower.cpp b/src/samd/ArduinoLowPower.cpp
@@ -23,9 +23,13 @@ void ArduinoLowPowerClass::sleep() {
 		USBDevice.detach();
 		restoreUSBDevice = true;
 	}
+	// Disable systick interrupt:  See https://www.avrfreaks.net/forum/samd21-samd21e16b-sporadically-locks-and-does-not-wake-standby-sleep-mode
+	SysTick->CTRL &= ~SysTick_CTRL_TICKINT_Msk;	
 	SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk;
 	__DSB();
 	__WFI();
+	// Enable systick interrupt
+	SysTick->CTRL |= SysTick_CTRL_TICKINT_Msk;	
 	if (restoreUSBDevice) {
 		USBDevice.attach();
 	}

Original file line number	Diff line number	Diff line change
`@@ -23,9 +23,13 @@ void ArduinoLowPowerClass::sleep() {`
`23`	`23`	`USBDevice.detach();`
`24`	`24`	`restoreUSBDevice = true;`
`25`	`25`	`}`
	`26`	`+ // Disable systick interrupt: See https://www.avrfreaks.net/forum/samd21-samd21e16b-sporadically-locks-and-does-not-wake-standby-sleep-mode`
	`27`	`+ SysTick->CTRL &= ~SysTick_CTRL_TICKINT_Msk;`
`26`	`28`	`SCB->SCR \|= SCB_SCR_SLEEPDEEP_Msk;`
`27`	`29`	`__DSB();`
`28`	`30`	`__WFI();`
	`31`	`+ // Enable systick interrupt`
	`32`	`+ SysTick->CTRL \|= SysTick_CTRL_TICKINT_Msk;`
`29`	`33`	`if (restoreUSBDevice) {`
`30`	`34`	`USBDevice.attach();`
`31`	`35`	`}`