wayne roberts / SX127x

Driver library for SX1272/SX1276 transceivers

Dependents:   LORA_RX LORA_TX WindConcentrator hid_test ... more

Driver library for SX1272 and SX1276 radio transceivers.

This device uses CSS modulation to provide much improved link budget. The RF hardware is same as in FSK devices, just with added LoRa spread-spectrum modem.

This library provides functions to configure radio chip and transmit & receive packets.

Using This Library

Library function service_radio() must be called continuously from main loop, to service interrupts from radio.

Board Specific implementation

FunctionPointer for rf_switch callback allows the program to implement control of RF switch unique to their board. Example options are:

• SKY13373 for external power amplifier implementation. Requires two DigitalOut pins.
• SKY13350 using PA_BOOST. requires two DigitalOut pins.
• PE4259-63: controlled directly by radio chip, no software function needed. However, in the case of SX1276MB1xAS, the RXTX pin on IO2 should be driven by this callback function when R16 is installed (without R15) on this shield board.

Some configurations may need to force the use of RFO or PA_BOOST, or a board could offer both options. The rf_switch function pointer callback should support the implementation choice on the board.

further reading

• LoRa modulation basics (dropbox PDF)
• OpenLoRa forum

--- a/sx127x_lora.cpp	Tue Jun 03 20:44:30 2014 +0000
+++ b/sx127x_lora.cpp	Mon Jun 30 17:05:12 2014 +0000
@@ -312,10 +312,7 @@
     // write PayloadLength bytes to fifo
     write_fifo(len);
 
-    if (m_xcvr.HF)
-        m_xcvr.femctx = 1;
-    else
-        m_xcvr.femcps = 0;
+
         
     // radio doesnt provide FhssChangeChannel with channel=0 for TX    
     if (RegHopPeriod > 0)
@@ -329,10 +326,7 @@
     if (!m_xcvr.RegOpMode.bits.LongRangeMode)
         return;
 
-    if (m_xcvr.HF)
-        m_xcvr.femctx = 0;
-    else
-        m_xcvr.femcps = 1;
+
         
     if (m_xcvr.RegDioMapping1.bits.Dio0Mapping != 0) {
         m_xcvr.RegDioMapping1.bits.Dio0Mapping = 0;    // DIO0 to RxDone
@@ -408,11 +402,6 @@
             read_fifo(RegRxNbBytes);
             return SERVICE_READ_FIFO;
         case 1: // TxDone
-            if (m_xcvr.HF)
-                m_xcvr.femctx = 0;
-            else
-                m_xcvr.femcps = 1;
-
             RegIrqFlags.octet = 0;
             RegIrqFlags.bits.TxDone = 1;
             m_xcvr.write_reg(REG_LR_IRQFLAGS, RegIrqFlags.octet);