stm32/powerctrl: Disable sys tick interrupt in stop mode on some STM32s.

pi-chm · dpgeorge · commit 0d8d91195070 · 2022-06-07T18:08:02.000+10:00
According to ST Errata ES0206 Rev 18, Section 2.2.1, on STM32F427x,
STM32F437x, STM32F429x and STM32F439x.

If the system tick interrupt is enabled during stop mode while certain
bits are set in the DBGMCU_CR, then the system will immediately wake
from stop mode.

Suggested workaround is to disable system tick timer interrupt when
entering stop mode.

According to ST Errate ES0394 Rev 11, Section 2.2.17, on STM32WB55Cx and
STM32WB35Cx.

If the system tick interrupt is enabled during stop 0, stop 1 or stop 2
while certain bits are set in DBGMCU_CR, then system will immediately
wake from stop mode but the system remains in low power state. The CPU
therefore fetches incorrect data from inactive Flash, which can cause a
hard fault.

Suggested workaround is to disable system tick timer interrupt when
entering stop mode.
diff --git a/ports/stm32/powerctrl.c b/ports/stm32/powerctrl.c
@@ -685,10 +685,17 @@ void powerctrl_enter_stop_mode(void) {
     // executed until after the clocks are reconfigured
     uint32_t irq_state = disable_irq();
 
-    #if defined(STM32H7)
+    #if defined(STM32H7) || \
+    defined(STM32F427xx) || defined(STM32F437xx) || \
+    defined(STM32F429xx) || defined(STM32F439xx) || \
+    defined(STM32WB55xx) || defined(STM32WB35xx)
     // Disable SysTick Interrupt
     // Note: This seems to be required at least on the H7 REV Y,
     // otherwise the MCU will leave stop mode immediately on entry.
+    // Note: According to ST Errata ES0206 Rev 18, Section 2.2.1 this is needed
+    // for STM32F427xx, STM32F437xx, STM32F429xx and STM32F439xx
+    // Note: According to ST Errata ES0394 Rev 11, Section 2.2.17 this is needed
+    // for STM32WB55xx and STM32WB35xx
     SysTick->CTRL &= ~SysTick_CTRL_TICKINT_Msk;
     #endif
 
@@ -849,7 +856,10 @@ void powerctrl_enter_stop_mode(void) {
     MICROPY_BOARD_LEAVE_STOP
     #endif
 
-    #if defined(STM32H7)
+    #if defined(STM32H7) || \
+    defined(STM32F427xx) || defined(STM32F437xx) || \
+    defined(STM32F429xx) || defined(STM32F439xx) || \
+    defined(STM32WB55xx) || defined(STM32WB35xx)
     // Enable SysTick Interrupt
     SysTick->CTRL |= SysTick_CTRL_TICKINT_Msk;
     #endif
