[LoRaWAN] Add methods to allow user-provided sleep function

keywords.txt

@@ -377,6 +377,7 @@ getLastToA	KEYWORD2
 dutyCycleInterval	KEYWORD2
 timeUntilUplink	KEYWORD2
 getMaxPayloadLen	KEYWORD2
+setSleepFunction	KEYWORD2
 
 #######################################
 # Constants (LITERAL1)

src/protocols/LoRaWAN/LoRaWAN.cpp

@@ -1377,7 +1377,7 @@ int16_t LoRaWANNode::receiveCommon(uint8_t dir, const LoRaWANChannel_t* dlChanne
     if(waitLen > this->scanGuard) {
       waitLen -= this->scanGuard;
     }
-    mod->hal->delay(waitLen);
+    this->sleepDelay(waitLen);
 
     // open Rx window by starting receive with specified timeout
     // TODO remove default arguments
@@ -1387,7 +1387,7 @@ int16_t LoRaWANNode::receiveCommon(uint8_t dir, const LoRaWANChannel_t* dlChanne
     RADIOLIB_DEBUG_PROTOCOL_PRINTLN("Opening Rx%d window (%d ms timeout)... <-- Rx Delay end ", window, (int)(timeoutHost / 1000 + scanGuard / 2));
     
     // wait for the timeout to complete (and a small additional delay)
-    mod->hal->delay(timeoutHost / 1000 + this->scanGuard / 2);
+    this->sleepDelay(timeoutHost / 1000 + this->scanGuard / 2);
     RADIOLIB_DEBUG_PROTOCOL_PRINTLN("Closing Rx%d window", window);
 
     // if the IRQ bit for Rx Timeout is not set, something is received, so stop the windows
@@ -3310,6 +3310,10 @@ uint8_t LoRaWANNode::getMaxPayloadLen() {
   return(curLen - 13 - this->fOptsUpLen);
 }
 
+void LoRaWANNode::setSleepFunction(SleepCb_t cb) {
+  this->sleepCb = cb;
+}
+
 int16_t LoRaWANNode::findDataRate(uint8_t dr, DataRate_t* dataRate) {
   int16_t state = this->phyLayer->standby();
   if(state != RADIOLIB_ERR_NONE) {
@@ -3434,6 +3438,18 @@ void LoRaWANNode::processAES(const uint8_t* in, size_t len, uint8_t* key, uint8_
   }
 }
 
+void LoRaWANNode::sleepDelay(RadioLibTime_t ms) {
+  // if the user did not provide sleep callback, or the duration is short, just call delay
+  if((this->sleepCb == nullptr) || (ms <= RADIOLIB_LORAWAN_DELAY_SLEEP_THRESHOLD)) {
+    Module* mod = this->phyLayer->getMod();
+    mod->hal->delay(ms);
+    return;
+  }
+
+  // otherwise, call the user-provided callback
+  this->sleepCb(ms);
+}
+
 int16_t LoRaWANNode::checkBufferCommon(const uint8_t *buffer, uint16_t size) {
   // check if there are actually values in the buffer
   size_t i = 0;

src/protocols/LoRaWAN/LoRaWAN.h

@@ -210,6 +210,9 @@
 
 #define RADIOLIB_LORAWAN_MAX_DOWNLINK_SIZE                      (250)
 
+// threshold at which sleeping via user callback enabled, in ms
+#define RADIOLIB_LORAWAN_DELAY_SLEEP_THRESHOLD                  (50)
+
 /*!
   \struct LoRaWANMacCommand_t
   \brief MAC command specification structure.
@@ -832,6 +835,18 @@ class LoRaWANNode {
     */
     uint8_t getMaxPayloadLen();
 
+    /*! \brief Callback to a user-provided sleep function. */
+    typedef void (*SleepCb_t)(RadioLibTime_t ms);
+
+    /*! 
+      \brief Set custom delay/sleep function callback. If set, LoRaWAN node will call
+      this function to wait for periods of time longer than RADIOLIB_LORAWAN_DELAY_SLEEP_THRESHOLD.
+      This can be used to lower the power consumption by putting the host microcontroller to sleep.
+      NOTE: Since this method will call a user-provided function, it is up to the user to ensure
+      that the time duration spent in that sleep function is accurate to at least 1 ms!
+    */
+    void setSleepFunction(SleepCb_t cb); 
+
     /*! 
       \brief TS009 Protocol Specification Verification switch
       (allows FPort 224 and cuts off uplink payload instead of rejecting if maximum length exceeded).
@@ -973,6 +988,8 @@ class LoRaWANNode {
     // allow port 226 for devices implementing TS011
     bool TS011 = false;
 
+    SleepCb_t sleepCb = nullptr;
+
     // this will reset the device credentials, so the device starts completely new
     void clearNonces();
 
@@ -1102,6 +1119,9 @@ class LoRaWANNode {
     // function to encrypt and decrypt payloads (regular uplink/downlink)
     void processAES(const uint8_t* in, size_t len, uint8_t* key, uint8_t* out, uint32_t fCnt, uint8_t dir, uint8_t ctrId, bool counter);
 
+    // function that allows sleeping via user-provided callback
+    void sleepDelay(RadioLibTime_t ms);
+
     // 16-bit checksum method that takes a uint8_t array of even length and calculates the checksum
     static uint16_t checkSum16(const uint8_t *key, uint16_t keyLen);