Added readCPUTemperature()

Author: ajs123

cores/nRF5/wiring.c

@@ -143,3 +143,44 @@ void systemOff(uint32_t pin, uint8_t wake_logic)
     NRF_POWER->SYSTEMOFF = 1;
   }
 }
+
+
+float readCPUTemperature()
+{
+  // These are defined simply to make the ensuing code easier to read. Ready and triggers are 0x01, and not ready is 0x00. 
+  // Many other library functions use a literal 0x00 to reset flags and a literal 0x01 for triggers, and test "done"
+  // flags for nonzero.  In this function, we used the defined constants. Using 0x00 and 0x01 would probably be fine
+  // because they're unlikely to ever change.
+  const uint32_t temp_ready = ( (TEMP_EVENTS_DATARDY_EVENTS_DATARDY_Generated << TEMP_EVENTS_DATARDY_EVENTS_DATARDY_Pos)
+                                && TEMP_EVENTS_DATARDY_EVENTS_DATARDY_Msk );
+
+  const uint32_t temp_not_ready = ( (TEMP_EVENTS_DATARDY_EVENTS_DATARDY_NotGenerated << TEMP_EVENTS_DATARDY_EVENTS_DATARDY_Pos)
+                                    && TEMP_EVENTS_DATARDY_EVENTS_DATARDY_Msk );
+
+  const uint32_t temp_trigger = ( (TEMP_TASKS_START_TASKS_START_Trigger << TEMP_TASKS_STOP_TASKS_STOP_Pos)
+                                  && TEMP_TASKS_START_TASKS_START_Msk );
+
+  const uint32_t temp_stop = ( (TEMP_TASKS_STOP_TASKS_STOP_Trigger << TEMP_TASKS_STOP_TASKS_STOP_Pos)
+                                  && TEMP_TASKS_STOP_TASKS_STOP_Msk );
+
+  uint8_t en;
+  int32_t temp;
+  (void) sd_softdevice_is_enabled(&en);
+  if (en) 
+  {
+    sd_temp_get(&temp);
+  }
+  else
+  {
+    NRF_TEMP->EVENTS_DATARDY = temp_not_ready; // Only needed in case another function is also looking at this event flag
+    NRF_TEMP->TASKS_START = temp_trigger; 
+  
+    bool done = false;
+    while (NRF_TEMP->EVENTS_DATARDY != temp_ready);
+    temp = NRF_TEMP->TEMP;                      // Per anomaly 29 (unclear whether still applicable), TASKS_STOP will clear the TEMP register.
+
+    NRF_TEMP->TASKS_STOP = temp_stop;           // Per anomaly 30 (unclear whether still applicable), the temp peripheral needs to be shut down
+    NRF_TEMP->EVENTS_DATARDY = temp_not_ready;
+  }
+  return temp / 4.0F;
+}

cores/nRF5/wiring.h

@@ -42,6 +42,12 @@ static inline bool isInISR(void)
   return (SCB->ICSR & SCB_ICSR_VECTACTIVE_Msk) != 0 ;
 }
 
+/*
+ * \brief Reads the on-chip temperature sensor, returning the temperature in degrees C
+ * with a resolution of 0.25 degrees.
+*/
+float readCPUTemperature();
+
 #ifdef __cplusplus
 }
 #endif