To implement power saving for NRF52 using System-Idle On

Author: IoTThinks

src/helpers/NRF52Board.cpp

@@ -3,9 +3,6 @@
 #include "nrf_sdm.h"
 #include <bluefruit.h>
 
-// For PowerSaving
-static SoftwareTimer wakeupTimer;
-
 static BLEDfu bledfu;
 
 static void connect_callback(uint16_t conn_handle) {
@@ -105,26 +102,18 @@ bool NRF52BoardOTA::startOTAUpdate(const char *id, char reply[]) {
   return true;
 }
 
-static void wakeUpCallback(TimerHandle_t xTimer) {
-  // To wake up based on timer
-  resumeLoop();
-  wakeupTimer.stop();
-}
-
 void NRF52Board::enterLightSleep(uint32_t secs) {
 #if defined(P_LORA_DIO_1)
-  // To prevent to enter suspendLoop when the loop has not processed the pending RX
-  if(digitalRead(P_LORA_DIO_1) == HIGH) {
-    return;
+  // To mark the start of the sleep
+  uint32_t startTime = millis();
+
+  // To wake up when a LoRa packet comes or sleep timeout. Safe to 49-day overflow
+  while (digitalRead(P_LORA_DIO_1) == LOW && (millis() - startTime < secs*1000)) {
+    // To enter System-on idle
+    __SEV(); // To clear any stale event flag
+    __WFE(); // To consume that event
+    __WFE(); // To actually puts CPU to sleep
   }
-
-  // To wake up periodically to do scheduled jobs
-  wakeupTimer.stop();
-  wakeupTimer.begin(secs * 1000, wakeUpCallback, nullptr, false);
-  wakeupTimer.start();
-
-  // To pause MCU to sleep
-  suspendLoop();
 #endif
 }
 

src/helpers/radiolib/RadioLibWrappers.cpp

@@ -29,11 +29,6 @@ void setFlag(void) {
 #elif defined(ESP32) && defined(P_LORA_DIO_1) // SX1262
   gpio_set_intr_type((gpio_num_t)P_LORA_DIO_1, GPIO_INTR_POSEDGE);
 #endif
-
-// To wakeup when there is a LoRa message
-#if defined(NRF52_PLATFORM)
-  resumeLoop();
-#endif
 }
 
 void RadioLibWrapper::begin() {