nrf52840: add workaround for RTC errata 20

include thered main stack for cmsis rtos

Author: nvlsianpu

rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h

@@ -354,7 +354,7 @@ __attribute__((used)) void _mutex_release (OS_ID *mutex) {
 /* Main Thread definition */
 extern void pre_main (void);
 
-#if defined(TARGET_MCU_NRF52832) ||\
+#if defined(TARGET_MCU_NRF52840) ||\
     defined(TARGET_MCU_NRF51822) || defined(TARGET_MCU_NRF52832) || defined (TARGET_STM32F334R8) ||\
     defined(TARGET_STM32F070RB) || defined(TARGET_STM32F072RB) || \
     defined(TARGET_STM32F302R8) || defined(TARGET_STM32F303K8) || defined (TARGET_STM32F334C8) ||\

targets/TARGET_NORDIC/TARGET_NRF5_SDK13/us_ticker.c

@@ -76,6 +76,20 @@ void COMMON_RTC_IRQ_HANDLER(void)
     }
 }
 
+// Function for fix errata 20: RTC Register values are invalid
+__STATIC_INLINE void errata_20(void)
+{
+#if defined(NRF52_ERRATA_20)
+    if (!softdevice_handler_is_enabled())
+    {
+    	NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
+        NRF_CLOCK->TASKS_LFCLKSTART = 1;
+        while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0) {}
+    }
+	NRF_RTC1->TASKS_STOP = 0;
+#endif    
+}
+
 #if (defined (__ICCARM__)) && defined(TARGET_MCU_NRF51822)//IAR
 __stackless __task 
 #endif
@@ -87,6 +101,8 @@ void common_rtc_init(void)
         return;
     }
 
+    errata_20();
+    
     NVIC_SetVector(RTC1_IRQn, (uint32_t)RTC1_IRQHandler);
 
     // RTC is driven by the low frequency (32.768 kHz) clock, a proper request

targets/targets.json

@@ -2560,7 +2560,7 @@
     "MCU_NRF52840": {
         "inherits": ["Target"],
         "core": "Cortex-M4F",
-        "macros": ["TARGET_NRF52840", "BLE_STACK_SUPPORT_REQD", "SOFTDEVICE_PRESENT", "S140", "NRF_SD_BLE_API_VERSION=5", "NRF52840_XXAA", "NRF_DFU_SETTINGS_VERSION=1"],
+        "macros": ["TARGET_NRF52840", "BLE_STACK_SUPPORT_REQD", "SOFTDEVICE_PRESENT", "S140", "NRF_SD_BLE_API_VERSION=5", "NRF52840_XXAA", "NRF_DFU_SETTINGS_VERSION=1", "NRF_SD_BLE_API_VERSION=5"],
         "extra_labels": ["NORDIC", "MCU_NRF52840", "NRF5_SDK13"],
         "OUTPUT_EXT": "hex",
         "is_disk_virtual": true,
@@ -2598,7 +2598,7 @@
     "NRF52840_DK": {
         "supported_form_factors": ["ARDUINO"],
         "inherits": ["MCU_NRF52840"],
-        "macros_add": ["BOARD_PCA10056", "CONFIG_GPIO_AS_PINRESET", "SWI_DISABLE0"],
+        "macros_add": ["BOARD_PCA10056", "CONFIG_GPIO_AS_PINRESET", "SWI_DISABLE0", "NRF52_ERRATA_20"],
         "device_has": ["ANALOGIN", "ERROR_PATTERN", "I2C", "I2C_ASYNCH", "INTERRUPTIN", "LOWPOWERTIMER", "PORTIN", "PORTINOUT", "PORTOUT", "PWMOUT", "RTC", "SERIAL", "SERIAL_ASYNCH", "SERIAL_FC", "SLEEP", "SPI", "SPI_ASYNCH", "SPISLAVE"],
         "release_versions": ["2", "5"],
         "device_name": "nRF52840_xxAA"