Fix #418: add strict LMIC_send apis

Author: terrillmoore

examples/compliance-otaa-halconfig/compliance-otaa-halconfig.ino

@@ -541,7 +541,7 @@ void do_send(osjob_t* j){
         Serial.println(F("test mode, not sending"));
     } else {
         // Prepare upstream data transmission at the next possible time.
-        if (LMIC_sendWithCallback(1, mydata, sizeof(mydata)-1, 0, sendComplete, j) == 0) {
+        if (LMIC_sendWithCallback_strict(1, mydata, sizeof(mydata)-1, 0, sendComplete, j) == 0) {
             Serial.println(F("Packet queued"));
         } else {
             Serial.println(F("Packet queue failure; sleeping"));

src/lmic/lmic.c

@@ -2723,9 +2723,49 @@ void LMIC_clrTxData (void) {
     engineUpdate();
 }
 
+dr_t LMIC_feasibleDataRateForFrame(dr_t dr, u1_t payloadSize) {
+    if (payloadSize > MAX_LEN_PAYLOAD) {
+        return dr;
+    }
+
+    const u1_t frameSize = payloadSize + OFF_DAT_OPTS + 5;
+    dr_t trialDr, nextDr;
+
+    for (trialDr = dr; ;) {
+        if (! LMICbandplan_isDataRateFeasible(trialDr))
+            break;
+        u1_t maxSizeThisDr = LMICbandplan_maxFrameLen(trialDr);
+        if (maxSizeThisDr == 0) {
+            break;
+        } else if (frameSize <= maxSizeThisDr) {
+            // we found one that is feasible!
+            return trialDr;
+        }
+        // try the next DR
+        nextDr = incDR(trialDr);
+        if (nextDr == trialDr)
+            break;
+        trialDr = nextDr;
+    }
+
+    // if we get here, we didn't find a working dr.
+    return dr;
+}
+
+static void adjustDrForFrame(u1_t len) {
+    dr_t newDr = LMIC_feasibleDataRateForFrame(LMIC.datarate, len);
+    if (newDr != LMIC.datarate) {
+        setDrTxpow(DRCHG_FRAMESIZE, newDr, KEEP_TXPOW);
+    }
+}
 
 void LMIC_setTxData (void) {
-    LMICOS_logEventUint32("LMIC_setTxData", (LMIC.pendTxPort << 24u) | (LMIC.pendTxConf << 16u) | (LMIC.pendTxLen << 0u));
+    adjustDrForFrame(LMIC.pendTxLen);
+    LMIC_setTxData_strict();
+}
+
+void LMIC_setTxData_strict (void) {
+    LMICOS_logEventUint32(__func__, (LMIC.pendTxPort << 24u) | (LMIC.pendTxConf << 16u) | (LMIC.pendTxLen << 0u));
     LMIC.opmode |= OP_TXDATA;
     if( (LMIC.opmode & OP_JOINING) == 0 ) {
         LMIC.txCnt = 0;             // reset the confirmed uplink FSM
@@ -2735,8 +2775,14 @@ void LMIC_setTxData (void) {
 }
 
 
-// send a message w/o callback
+// send a message, attempting to adjust TX data rate
 lmic_tx_error_t LMIC_setTxData2 (u1_t port, xref2u1_t data, u1_t dlen, u1_t confirmed) {
+    adjustDrForFrame(dlen);
+    return LMIC_setTxData2_strict(port, data, dlen, confirmed);
+}
+
+// send a message w/o callback; do not adjust data rate
+lmic_tx_error_t LMIC_setTxData2_strict (u1_t port, xref2u1_t data, u1_t dlen, u1_t confirmed) {
     if ( LMIC.opmode & OP_TXDATA ) {
         // already have a message queued
         return LMIC_ERROR_TX_BUSY;
@@ -2748,7 +2794,7 @@ lmic_tx_error_t LMIC_setTxData2 (u1_t port, xref2u1_t data, u1_t dlen, u1_t conf
     LMIC.pendTxConf = confirmed;
     LMIC.pendTxPort = port;
     LMIC.pendTxLen  = dlen;
-    LMIC_setTxData();
+    LMIC_setTxData_strict();
     if ( (LMIC.opmode & OP_TXDATA) == 0 ) {
         if (LMIC.txrxFlags & TXRX_LENERR) {
             return LMIC_ERROR_TX_NOT_FEASIBLE;
@@ -2760,10 +2806,19 @@ lmic_tx_error_t LMIC_setTxData2 (u1_t port, xref2u1_t data, u1_t dlen, u1_t conf
     return 0;
 }
 
-// send a message with callback
+// send a message with callback; try to adjust data rate
 lmic_tx_error_t LMIC_sendWithCallback (
     u1_t port, xref2u1_t data, u1_t dlen, u1_t confirmed,
     lmic_txmessage_cb_t *pCb, void *pUserData
+) {
+    adjustDrForFrame(dlen);
+    return LMIC_sendWithCallback_strict(port, data, dlen, confirmed, pCb, pUserData);
+}
+
+// send a message with callback; do not adjust datarate
+lmic_tx_error_t LMIC_sendWithCallback_strict (
+    u1_t port, xref2u1_t data, u1_t dlen, u1_t confirmed,
+    lmic_txmessage_cb_t *pCb, void *pUserData
 ) {
     lmic_tx_error_t const result = LMIC_setTxData2(port, data, dlen, confirmed);
     if (result == 0) {

src/lmic/lmic.h

@@ -178,7 +178,7 @@ struct lmic_saved_adr_state_s {
 typedef struct lmic_saved_adr_state_s   lmic_saved_adr_state_t;
 
 // Keep in sync with evdefs.hpp::drChange
-enum { DRCHG_SET, DRCHG_NOJACC, DRCHG_NOACK, DRCHG_NOADRACK, DRCHG_NWKCMD };
+enum { DRCHG_SET, DRCHG_NOJACC, DRCHG_NOACK, DRCHG_NOADRACK, DRCHG_NWKCMD, DRCHG_FRAMESIZE };
 enum { KEEP_TXPOW = -128 };
 
 
@@ -614,8 +614,11 @@ void  LMIC_init         (void);
 void  LMIC_reset        (void);
 void  LMIC_clrTxData    (void);
 void  LMIC_setTxData    (void);
+void  LMIC_setTxData_strict(void);
 lmic_tx_error_t LMIC_setTxData2(u1_t port, xref2u1_t data, u1_t dlen, u1_t confirmed);
+lmic_tx_error_t LMIC_setTxData2_strict(u1_t port, xref2u1_t data, u1_t dlen, u1_t confirmed);
 lmic_tx_error_t LMIC_sendWithCallback(u1_t port, xref2u1_t data, u1_t dlen, u1_t confirmed, lmic_txmessage_cb_t *pCb, void *pUserData);
+lmic_tx_error_t LMIC_sendWithCallback_strict(u1_t port, xref2u1_t data, u1_t dlen, u1_t confirmed, lmic_txmessage_cb_t *pCb, void *pUserData);
 void  LMIC_sendAlive    (void);
 
 #if !defined(DISABLE_BEACONS)

src/lmic/lmic_compliance.c

@@ -686,7 +686,7 @@ static void acSendUplink(void) {
 
     // don't try to send if busy; might be sending echo message.
     lmic_tx_error_t const eSend =
-        LMIC_sendWithCallback(
+        LMIC_sendWithCallback_strict(
             LORAWAN_PORT_COMPLIANCE,
             payload, sizeof(payload),
             /* confirmed? */
@@ -725,7 +725,7 @@ static void sendUplinkCompleteCb(void *pUserData, int fSuccess) {
 static void acSendUplinkBuffer(void) {
     // send uplink data.
     lmic_tx_error_t const eSend =
-        LMIC_sendWithCallback(
+        LMIC_sendWithCallback_strict(
             LORAWAN_PORT_COMPLIANCE,
             LMIC_Compliance.uplinkMessage, LMIC_Compliance.uplinkSize,
             /* confirmed? */ (LMIC_Compliance.fsmFlags & LMIC_COMPLIANCE_FSM_CONFIRM) != 0,