Driver library for SX1272/SX1276 transceivers

Dependents:   LORA_RX LORA_TX WindConcentrator hid_test ... more

/media/uploads/dudmuck/lora.png

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.

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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

Revision:
3:3bf2515b1eed
Parent:
2:fdae76e1215e
Child:
4:d987ac2836bf
diff -r fdae76e1215e -r 3bf2515b1eed sx127x_fsk.cpp
--- a/sx127x_fsk.cpp	Wed Apr 30 22:49:43 2014 +0000
+++ b/sx127x_fsk.cpp	Fri May 02 01:18:59 2014 +0000
@@ -15,9 +15,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
- 
-//SX127x_fsk::SX127x_fsk(PinName mosi, PinName miso, PinName sclk, PinName cs, PinName rst, PinName dio_0, PinName dio_1, PinName fem_ctx, PinName fem_cps) : SX127x(mosi, miso, sclk, cs, rst, dio_0, dio_1, fem_ctx, fem_cps)
-SX127x_fsk::SX127x_fsk(SX127x r) : m_xcvr(r)
+
+SX127x_fsk::SX127x_fsk(SX127x& r) : m_xcvr(r)
 {
 }
 
@@ -32,8 +31,9 @@
     m_xcvr.m_cs = 0;
     m_xcvr.m_spi.write(REG_FIFO | 0x80); // bit7 is high for writing to radio
     
-    if (!m_xcvr.RegOpMode.bits.LongRangeMode && RegPktConfig1.bits.PacketFormatVariable)
+    if (!m_xcvr.RegOpMode.bits.LongRangeMode && RegPktConfig1.bits.PacketFormatVariable) {
         m_xcvr.m_spi.write(len);
+    }
     
     for (i = 0; i < len; i++) {
         m_xcvr.m_spi.write(m_xcvr.tx_buf[i]);
@@ -49,13 +49,28 @@
     m_xcvr.write_reg(REG_OPMODE, m_xcvr.RegOpMode.octet);
     wait(0.01);
     
-    /*RegOpMode.octet = read_reg(REG_OPMODE);
-    printf("setloraoff:%02x\r\n", RegOpMode.octet);*/
-    
-    // todo: read FSK regsiters
-    //SX1272ReadBuffer( REG_OPMODE, SX1272Regs + 1, 0x70 - 1 );
     RegPktConfig1.octet = m_xcvr.read_reg(REG_FSK_PACKETCONFIG1);
     RegPktConfig2.word = m_xcvr.read_u16(REG_FSK_PACKETCONFIG2);
+    RegRxConfig.octet = m_xcvr.read_u16(REG_FSK_RXCONFIG);
+    RegPreambleDetect.octet = m_xcvr.read_reg(REG_FSK_PREAMBLEDETECT);
+    RegSyncConfig.octet = m_xcvr.read_reg(REG_FSK_SYNCCONFIG);
+    RegFifoThreshold.octet = m_xcvr.read_reg(REG_FSK_FIFOTHRESH);
+    RegAfcFei.octet = m_xcvr.read_reg(REG_FSK_AFCFEI);
+    
+    if (!RegFifoThreshold.bits.TxStartCondition) {
+        RegFifoThreshold.bits.TxStartCondition = 1; // start TX on fifoEmpty==0
+        m_xcvr.write_reg(REG_FSK_FIFOTHRESH, RegFifoThreshold.octet);
+    }
+    
+    if (RegSyncConfig.bits.AutoRestartRxMode != 1) {
+        RegSyncConfig.bits.AutoRestartRxMode = 1;
+        m_xcvr.write_reg(REG_FSK_SYNCCONFIG, RegSyncConfig.octet);
+    }
+    
+    if (RegPreambleDetect.bits.PreambleDetectorTol != 10) {
+        RegPreambleDetect.bits.PreambleDetectorTol = 10;
+        m_xcvr.write_reg(REG_FSK_PREAMBLEDETECT, RegPreambleDetect.octet);
+    }
     
     m_xcvr.set_opmode(RF_OPMODE_STANDBY);     
 }
@@ -91,7 +106,7 @@
 
 uint32_t SX127x_fsk::get_rx_bw_hz(uint8_t addr)
 {
-    FSKRegRxBw_t reg_bw;
+    RegRxBw_t reg_bw;
     uint8_t mantissa;
     
     if (m_xcvr.RegOpMode.bits.LongRangeMode)
@@ -151,7 +166,7 @@
 void SX127x_fsk::start_tx(uint16_t arg_len)
 {
     uint16_t pkt_buf_len;
-    FSKRegIrqFlags2_t RegIrqFlags2;
+    RegIrqFlags2_t RegIrqFlags2;
     int maxlen = FSK_FIFO_SIZE-1;
     
     if (m_xcvr.RegOpMode.bits.Mode == RF_OPMODE_RECEIVER) {
@@ -164,7 +179,6 @@
     }
 
     if (RegPktConfig1.bits.PacketFormatVariable) {
-        printf("variable-fmt %d\r\n", arg_len);
         pkt_buf_len = arg_len;
     } else {
         pkt_buf_len = RegPktConfig2.bits.PayloadLength;
@@ -183,7 +197,6 @@
                 printf("var-oversized %d\r\n", pkt_buf_len);
             } else {
                 //setup_FifoLevel(NO_EDGE); // disable
-                printf("var-write-fifo %d\r\n", pkt_buf_len);
                 write_fifo(pkt_buf_len);
                 //remaining_ = 0; // all was sent
             }
@@ -207,6 +220,20 @@
     
 }
 
+void SX127x_fsk::config_dio0_for_pktmode_rx()
+{
+    if (RegPktConfig1.bits.CrcOn) {
+        if (m_xcvr.RegDioMapping1.bits.Dio0Mapping != 1) {
+            m_xcvr.RegDioMapping1.bits.Dio0Mapping = 1; // to CrcOk
+            m_xcvr.write_reg(REG_DIOMAPPING1, m_xcvr.RegDioMapping1.octet);
+        }
+    } else { // Crc Off, use PayloadReady
+        if (m_xcvr.RegDioMapping1.bits.Dio0Mapping != 0) {
+            m_xcvr.RegDioMapping1.bits.Dio0Mapping = 0; // to PayloadReady
+            m_xcvr.write_reg(REG_DIOMAPPING1, m_xcvr.RegDioMapping1.octet);
+        }
+    }
+}
 
 void SX127x_fsk::start_rx()
 {
@@ -218,6 +245,9 @@
         m_xcvr.set_opmode(RF_OPMODE_STANDBY);
         wait(0.01);
     }
+    
+    config_dio0_for_pktmode_rx();
+    
     m_xcvr.set_opmode(RF_OPMODE_RECEIVER);        
 }
 
@@ -230,17 +260,19 @@
             m_xcvr.set_opmode(RF_OPMODE_STANDBY);
             return SERVICE_TX_DONE;
         }
-    } else if (m_xcvr.RegOpMode.bits.Mode == RF_OPMODE_RECEIVER) {
-        uint8_t len;
+    } else if (m_xcvr.RegOpMode.bits.Mode == RF_OPMODE_RECEIVER && m_xcvr.dio0) {
+        if (RegRxConfig.bits.AfcAutoOn)
+            RegAfcValue = m_xcvr.read_s16(REG_FSK_AFCMSB);
+            
         if (RegPktConfig1.bits.PacketFormatVariable) {
-            len = m_xcvr.read_reg(REG_FIFO);
+            rx_buf_length = m_xcvr.read_reg(REG_FIFO);
         } else {
-            len = RegPktConfig2.bits.PayloadLength;
+            rx_buf_length = RegPktConfig2.bits.PayloadLength;
         }
         
         m_xcvr.m_cs = 0;
         m_xcvr.m_spi.write(REG_FIFO); // bit7 is low for reading from radio
-        for (i = 0; i < len; i++) {
+        for (i = 0; i < rx_buf_length; i++) {
             m_xcvr.rx_buf[i] = m_xcvr.m_spi.write(0);
         }
         m_xcvr.m_cs = 1;