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Disable SAMD21 SysTick interrupt during sleep #84

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Disable SAMD21 SysTick interrupt during sleep #84

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@robdmob robdmob commented Feb 16, 2022 •
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This addresses a problem I experienced using an Adafruit Feather M0 where the board would suddenly refuse to wake up after a random time (4 - 12 hours). I found the solution in a discussion on the Atmel community forum: https://community.atmel.com/comment/2625116#comment-2625116.

In summary, due to a hardware bug on the SAMD21 platform it is possible for the SysTick interrupt to fire during wakeup before the RAM has had time to reinitialise which results in a hard fault. This can be prevented by disabling the SysTick interrupt before sleep and then reenabling it immediately after wakeup.

SysTick->CTRL &= ~SysTick_CTRL_TICKINT_Msk;  // Disable SysTick interrupt
__DSB();   // Data sync to ensure outgoing memory accesses complete
__WFI();   // Wait for interrupt (places device in sleep mode)
SysTick->CTRL |= SysTick_CTRL_TICKINT_Msk;   // Enable SysTick interrupt

After making this change the board has now been running for over two weeks with no problems.

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Disable SAMD21 SysTick interrupt during sleep
42b760b 
Disabling the systick timer interrupt during sleep has previously been discussed on the Microchip/Atmel community forum: https://community.atmel.com/comment/2625116#comment-2625116.

In summary, due to a hardware bug on the SAMD21, the SysTick interrupts become active before the flash has powered up from sleep, causing a hard fault after a random time. To prevent this the SysTick interrupts are disabled before entering sleep mode and enabled oncemore after the processor has woken up:

SysTick->CTRL &= ~SysTick_CTRL_TICKINT_Msk;  // Disable SysTick interrupts
__DSB();   // Data sync to ensure outgoing memory accesses complete
__WFI();   // Wait for interrupt (places device in sleep mode)
SysTick->CTRL |= SysTick_CTRL_TICKINT_Msk;   // Enable SysTick interrupts
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CLAassistant commented Feb 16, 2022 •
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Memory usage change @ 42b760b

Board flash % RAM for global variables %
arduino:samd:arduino_zero_edbg 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkr1000 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrfox1200 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrgsm1400 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrnb1500 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrvidor4000 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrwan1300 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrwan1310 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrwifi1010 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrzero 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:nano_33_iot 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
Click for full report table
Board examples/Epoch
flash		 % examples/Epoch
RAM for global variables		 % examples/SimpleRTC
flash		 % examples/SimpleRTC
RAM for global variables		 % examples/SimpleRTCAlarm
flash		 % examples/SimpleRTCAlarm
RAM for global variables		 % examples/SleepRTCAlarm
flash		 % examples/SleepRTCAlarm
RAM for global variables		 %
arduino:samd:arduino_zero_edbg 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkr1000 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrfox1200 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrgsm1400 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrnb1500 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrvidor4000 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrwan1300 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrwan1310 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrwifi1010 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrzero 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:nano_33_iot 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
Click for full report CSV 
Board,examples/Epoch<br>flash,%,examples/Epoch<br>RAM for global variables,%,examples/SimpleRTC<br>flash,%,examples/SimpleRTC<br>RAM for global variables,%,examples/SimpleRTCAlarm<br>flash,%,examples/SimpleRTCAlarm<br>RAM for global variables,%,examples/SleepRTCAlarm<br>flash,%,examples/SleepRTCAlarm<br>RAM for global variables,%
arduino:samd:arduino_zero_edbg,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkr1000,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrfox1200,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrgsm1400,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrnb1500,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrvidor4000,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrwan1300,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrwan1310,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrwifi1010,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrzero,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:nano_33_iot,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0

@per1234 per1234 added topic: code Related to content of the project itself type: imperfection Perceived defect in any part of project labels Feb 17, 2022
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github-actions bot commented Jul 2, 2022

Memory usage change @ 89695db

Board flash % RAM for global variables %
arduino:samd:arduino_zero_edbg 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkr1000 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrfox1200 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrgsm1400 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrnb1500 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrvidor4000 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrwan1300 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrwan1310 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrwifi1010 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:mkrzero 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
arduino:samd:nano_33_iot 🔺 0 - +20 0.0 - +0.01 0 - 0 0.0 - 0.0
Click for full report table
Board examples/Epoch
flash		 % examples/Epoch
RAM for global variables		 % examples/SimpleRTC
flash		 % examples/SimpleRTC
RAM for global variables		 % examples/SimpleRTCAlarm
flash		 % examples/SimpleRTCAlarm
RAM for global variables		 % examples/SleepRTCAlarm
flash		 % examples/SleepRTCAlarm
RAM for global variables		 %
arduino:samd:arduino_zero_edbg 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkr1000 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrfox1200 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrgsm1400 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrnb1500 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrvidor4000 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrwan1300 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrwan1310 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrwifi1010 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:mkrzero 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
arduino:samd:nano_33_iot 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0 20 0.01 0 0.0
Click for full report CSV 
Board,examples/Epoch<br>flash,%,examples/Epoch<br>RAM for global variables,%,examples/SimpleRTC<br>flash,%,examples/SimpleRTC<br>RAM for global variables,%,examples/SimpleRTCAlarm<br>flash,%,examples/SimpleRTCAlarm<br>RAM for global variables,%,examples/SleepRTCAlarm<br>flash,%,examples/SleepRTCAlarm<br>RAM for global variables,%
arduino:samd:arduino_zero_edbg,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkr1000,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrfox1200,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrgsm1400,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrnb1500,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrvidor4000,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrwan1300,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrwan1310,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrwifi1010,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:mkrzero,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0
arduino:samd:nano_33_iot,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,20,0.01,0,0.0

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@robdmob @CLAassistant @per1234