UNTESTED ADR back-off according to spec. Details about EU DR6

Author: clavisound

SlimLoRa.cpp

@@ -322,7 +322,7 @@ void SlimLoRa::printMAC(){
 	Serial.print(F("Rx1 DR offset\t: "));Serial.println(GetRx1DataRateOffset());
 	Serial.print(F("Rx2 DR RAM\t: "));Serial.println(rx2_data_rate_);
 	Serial.print(F("Rx2 DR EEPROM\t: "));Serial.println(GetRx2DataRate());
-	Serial.print(F("ADR_ACK_cnt\t: "));Serial.println(adr_ack_counter_);
+	Serial.print(F("ADR_ACK_cnt\t: "));Serial.println(adr_ack_limit_counter_);
 }
 #endif // DEBUG_SLIM
 
@@ -758,7 +758,10 @@ void SlimLoRa::RfmSendPacket(uint8_t *packet, uint8_t packet_length, uint8_t cha
 	// semi TODO fCnt don't increase if we havee UNCONFIRMED_DATA_UP and NbTrans to do.
 	if ( NbTrans_counter == 0 ) {
 		tx_frame_counter_++;
-		adr_ack_counter_++;
+		adr_ack_limit_counter_++;
+		if ( adr_ack_limit_counter_ >= LORAWAN_ADR_ACK_LIMIT ) {
+			adr_ack_delay_counter_++;
+		}
 		NbTrans_counter = NbTrans;
 	}
 
@@ -1274,7 +1277,9 @@ int8_t SlimLoRa::ProcessJoinAccept(uint8_t window) {
 	rx_frame_counter_ = 0;
 	SetRxFrameCounter();
 
-	adr_ack_counter_ = 0;
+	// reset counters. EVAL: I use this twice. Maybe better a function?
+	adr_ack_limit_counter_ = 0;
+	adr_ack_delay_counter_ = 0;
 	NbTrans_counter = NbTrans;
 
 	has_joined_ = true;
@@ -1379,7 +1384,11 @@ void SlimLoRa::ProcessFrameOptions(uint8_t *options, uint8_t f_options_length) {
 				new_rx2_dr = options[i + 1] >> 4; 
 				tx_power   = options[i + 1] & 0xF;
 
+				#if defined(EU_DR6)
 				if (new_rx2_dr == 0xF || (new_rx2_dr >= SF12BW125 && new_rx2_dr <= SF7BW250)) { // Reversed table index
+				#else
+				if (new_rx2_dr == 0xF || (new_rx2_dr >= SF12BW125 && new_rx2_dr <= SF7BW125)) { // Reversed table index
+				#endif
 					status |= 0x2;	// DR ACK
 				}
 				// tx_power = 15 or less than 7
@@ -1433,7 +1442,11 @@ void SlimLoRa::ProcessFrameOptions(uint8_t *options, uint8_t f_options_length) {
 				if (new_rx1_dr_offset <= LORAWAN_EU868_RX1_DR_OFFSET_MAX) {
 					status |= 0x4;
 				}
+				#if defined(EU_DR6)
 				if (new_rx2_dr >= SF12BW125 && new_rx2_dr <= SF7BW250) { // Reversed table index
+				#else
+				if (new_rx2_dr >= SF12BW125 && new_rx2_dr <= SF7BW125) { // Reversed table index
+				#endif
 					status |= 0x2;
 				}
 
@@ -1597,8 +1610,13 @@ int8_t SlimLoRa::ProcessDownlink(uint8_t window) {
 
 	if (window == 1) {
 		rx1_offset_dr = data_rate_ + rx1_data_rate_offset_; // Reversed table index
+		#if defined(EU_DR6)
 		if (rx1_offset_dr > SF7BW250) {
 			rx1_offset_dr = SF7BW250;
+		#else
+		if (rx1_offset_dr > SF7BW125) {
+			rx1_offset_dr = SF7BW125;
+		#endif
 		}
 		rx_delay = CalculateRxDelay(rx1_offset_dr, rx1_delay_micros_);
 		packet_length = RfmReceivePacket(packet, sizeof(packet), channel_, rx1_offset_dr, tx_done_micros_ + rx_delay);
@@ -1670,7 +1688,8 @@ int8_t SlimLoRa::ProcessDownlink(uint8_t window) {
 
 	// We received downlink. Reset some values.
 	// Reset ADR acknowledge counter
-	adr_ack_counter_ = 0; 
+	adr_ack_limit_counter_ = 0; 
+	adr_ack_delay_counter_ = 0; 
 	// Reset NbTrans
 	NbTrans_counter = NbTrans;
 
@@ -1837,14 +1856,29 @@ void SlimLoRa::Transmit(uint8_t fport, uint8_t *payload, uint8_t payload_length)
 	EncryptPayload(payload, payload_length, tx_frame_counter_, LORAWAN_DIRECTION_UP);
 
 	// ADR back-off
-	if (adr_enabled_ && adr_ack_counter_ >= LORAWAN_ADR_ACK_LIMIT + LORAWAN_ADR_ACK_DELAY) {
+	// TODO p. 17, after first increase if DR, increase every LORAWAN_ADR_ACK_DELAY overflow
+	if (adr_enabled_ && adr_ack_limit_counter_ >= LORAWAN_ADR_ACK_LIMIT && adr_ack_delay_counter_ == 0 ) {
+		adr_ack_delay_counter_++; // this way, this if statement will be executed only once
+		if ( data_rate_ > SF12BW125 ) {
+			data_rate_--;
+		}
+	// EVAL: I think the order is important for the HOPE
+	SetPower(16);
+#if DEBUG_SLIM >= 1
+	Serial.print(F("\nADR backoff 1st stage, DR: "));Serial.print(data_rate_);
+#endif
+	}
+
+	// Increase DR every overflow of LORAWAN_ADR_ACK_DELAY
+	if (adr_enabled_ && adr_ack_delay_counter_ >= LORAWAN_ADR_ACK_DELAY ) {
+		adr_ack_delay_counter_ = 0; // reset overflow
 		if ( data_rate_ > SF12BW125 ) {
-			data_rate_++;
+			data_rate_--;
 		}
 	// EVAL: I think the order is important for the HOPE
 	SetPower(16);
 #if DEBUG_SLIM >= 1
-	Serial.print(F("\nADR backoff, DR: "));Serial.print(data_rate_);
+	Serial.print(F("\nADR backoff 2nd stage, DR: "));Serial.print(data_rate_);
 #endif
 	}
 
@@ -1870,9 +1904,9 @@ void SlimLoRa::Transmit(uint8_t fport, uint8_t *payload, uint8_t payload_length)
 	if (adr_enabled_) {
 		packet[packet_length] |= LORAWAN_FCTRL_ADR;
 
-		// Request ADR if adr_ack_counter_ is over the limit of LORAWAN_ADR_ACK_LIMIT
+		// Request ADR if adr_ack_limit_counter_ is over the limit of LORAWAN_ADR_ACK_LIMIT
 		// p. 17
-		if (adr_ack_counter_ >= LORAWAN_ADR_ACK_LIMIT ) {
+		if (adr_ack_limit_counter_ >= LORAWAN_ADR_ACK_LIMIT ) {
 			packet[packet_length] |= LORAWAN_FCTRL_ADR_ACK_REQ;
 		}
 	}

SlimLoRa.h

@@ -266,7 +266,7 @@
 // LoRaWAN spreading factors
 // TODO for other regions. Example: DR0 for US902 is SF10BW125 and DR8 is SF12BW500
 // check https://www.thethingsnetwork.org/docs/lorawan/regional-parameters/
-#define FSK	    7 // TODO only 868.8 Mhz
+//#define FSK	    7 // TODO only 868.8 Mhz
 #define SF7BW250    6 // only 868.3 Mhz
 #define SF7BW125    5
 #define SF8BW125    4
@@ -299,11 +299,15 @@ class SlimLoRa {
     void SetPower(uint8_t power);
     bool GetHasJoined();
     void GetDevAddr(uint8_t *dev_addr);
-    bool adr_enabled_	= true;
-    uint8_t data_rate_ = SF7BW125;
-    uint16_t tx_frame_counter_ = 0;
-    uint16_t rx_frame_counter_ = 0;
-    uint8_t adr_ack_counter_ = 0;
+
+    // ADR variables
+    bool 	adr_enabled_;
+    uint8_t	adr_ack_limit_counter_;
+    uint8_t	adr_ack_delay_counter_;
+
+    uint8_t data_rate_;
+    uint16_t tx_frame_counter_;
+    uint16_t rx_frame_counter_;
     uint8_t NbTrans = NBTRANS;	// changed by the LNS or by DEFINE
     uint8_t NbTrans_counter;	// if NbTrans_counter is the same with NbTrans, send new message
     uint8_t pseudo_byte_;
@@ -342,8 +346,8 @@ class SlimLoRa {
   private:
 #endif
     uint8_t pin_nss_;	// TODO TinyLoRa irg_, rst_ bat_; bat=battery level pin
-    uint8_t channel_ = 0;
-    uint8_t rx1_data_rate_offset_ = 0;
+    uint8_t channel_;
+    uint8_t rx1_data_rate_offset_;
     uint8_t rx2_data_rate_ = RX_SECOND_WINDOW;
     uint32_t rx1_delay_micros_;
     bool has_joined_	= false;

library.json

@@ -1,6 +1,6 @@
 {
   "name": "SlimLoRa",
-  "version": "0.6.11",
+  "version": "0.6.12",
   "description": "LoRaWAN library with OTAA join, ADR support and most important MAC commands for EU868 suitable for AVR's with 32Kbytes. It uses 14kBytes of program flash instead of 52kBytes of RadioLib or 32kBytes of LMIC. Tested avr32u4 / ATmega32u4 and HopeRF 95w (SX1276) on Adafruit Feather. ABP untested. Session is stored to EEPROM. Testers wanted and PR's for other regions. It supports downlinks.",
   "keywords": "LoRaWAN, rfm95w, hoperf, SX1276, radio, communication",
   "repository":

library.properties

@@ -1,5 +1,5 @@
 name=SlimLoRa
-version=0.6.11
+version=0.6.12
 author=clavisound
 maintainer=clavisound
 sentence=SlimLoRa Library