Add workaround for F429 hardfault

Marcelo Salazar · Arto Kinnunen · commit 1aa999ed0a93 · 2020-03-31T09:38:25.000+03:00
diff --git a/targets/TARGET_STM/TARGET_STM32F4/device/stm32f4xx_hal_pwr.c b/targets/TARGET_STM/TARGET_STM32F4/device/stm32f4xx_hal_pwr.c
@@ -392,6 +392,9 @@ void HAL_PWR_EnterSLEEPMode(uint32_t Regulator, uint8_t SLEEPEntry)
   {   
     /* Request Wait For Interrupt */
     __WFI();
+    __NOP(); // Workaround for STM32F4 errata
+    __NOP(); // see chapter 2.1.3 - Debugging Sleep/Stop mode with WFE/WFI entry
+    __NOP(); // https://www.st.com/resource/en/errata_sheet/dm00037591-stm32f405-407xx-and-stm32f415-417xx-device-limitations-stmicroelectronics.pdf
   }
   else
   {

Original file line number	Diff line number	Diff line change
`@@ -392,6 +392,9 @@ void HAL_PWR_EnterSLEEPMode(uint32_t Regulator, uint8_t SLEEPEntry)`
`392`	`392`	`{`
`393`	`393`	`/* Request Wait For Interrupt */`
`394`	`394`	`__WFI();`
	`395`	`+ __NOP(); // Workaround for STM32F4 errata`
	`396`	`+ __NOP(); // see chapter 2.1.3 - Debugging Sleep/Stop mode with WFE/WFI entry`
	`397`	`+ __NOP(); // https://www.st.com/resource/en/errata_sheet/dm00037591-stm32f405-407xx-and-stm32f415-417xx-device-limitations-stmicroelectronics.pdf`
`395`	`398`	`}`
`396`	`399`	`else`
`397`	`400`	`{`