Fix matthijskooijman#77: Enable long messages

README.md

@@ -56,6 +56,7 @@ requires C99 mode to be enabled by default.
 		- [Disabling Class B MAC commands](#disabling-class-b-mac-commands)
 		- [Disabling user events](#disabling-user-events)
 		- [Disabling external reference to `onEvent()`](#disabling-external-reference-to-onevent)
+		- [Enabling long messages](#enabling-long-messages)
 		- [Special purpose](#special-purpose)
 - [Supported hardware](#supported-hardware)
 - [Pre-Integrated Boards](#pre-integrated-boards)
@@ -319,6 +320,10 @@ Code to handle registered callbacks for tx, rx, and events can be suppressed by
 
 In some embedded systems, `onEvent()` may be defined for some other purpose; so the weak reference to the function `onEvent` will be satified, causing the LMIC to try to call that function. All reference to `onEvent()` can be suppressed by setting `LMIC_ENABLE_onEvent` to 0.   This C preprocessor macro is always defined as a post-condition of `#include "config.h"`; if non-zero, a weak reference to `onEvent()` will be used; if zero, the user `onEvent()` function is not supported, and the client must register an event handler explicitly.
 
+#### Enabling long messages
+
+To save RAM for simple devices, the LMIC allows message length to be limited to 64 bytes instead of the LoRaWAN standard of 255 bytes max. This saves about 2*192 bytes of RAM. Unfortunately, compliance tests require the full message size. Long messages are enabled by setting `LMIC_ENABLE_long_messages` to 1, or disabled by setting it to zero. This C preprocessor macro is always defined as a post-condition of `#include "config.h"`; if non-zero, the maximum frame size is 255 bytes, and if zero, the maximum frame size is 64 bytes.
+
 #### Special purpose
 
 `#define DISABLE_INVERT_IQ_ON_RX` disables the inverted Q-I polarity on RX. If this is defined, end-devices will be able

src/lmic/config.h

@@ -192,4 +192,10 @@
 # define LMIC_ENABLE_onEvent 1
 #endif
 
+// LMIC_ENABLE_long_messages
+// LMIC certification requires that this be enabled.
+#if !defined(LMIC_ENABLE_long_messages)
+# define LMIC_ENABLE_long_messages 1        /* PARAM */
+#endif
+
 #endif // _lmic_config_h_

src/lmic/lorabase.h

@@ -59,7 +59,7 @@ enum { ILLEGAL_RPS = 0xFF };
 
 // Global maximum frame length
 enum { STD_PREAMBLE_LEN  =  8 };
-enum { MAX_LEN_FRAME     = 64 };
+enum { MAX_LEN_FRAME     =  LMIC_ENABLE_long_messages ? 255 : 64 };
 enum { LEN_DEVNONCE      =  2 };
 enum { LEN_ARTNONCE      =  3 };
 enum { LEN_NETID         =  3 };

src/lmic/radio.c

@@ -634,7 +634,7 @@ static void rxlora (u1_t rxmode) {
     // set LNA gain
     writeReg(RegLna, LNA_RX_GAIN);
     // set max payload size
-    writeReg(LORARegPayloadMaxLength, 64);
+    writeReg(LORARegPayloadMaxLength, MAX_LEN_FRAME);
 #if !defined(DISABLE_INVERT_IQ_ON_RX)
     // use inverted I/Q signal (prevent mote-to-mote communication)