wayne roberts
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
Diff: sx127x_lora.cpp
- Revision:
- 19:1ee6ef1ab73f
- Parent:
- 18:0ecb6adb7c0b
- Child:
- 23:1df3dddcb43e
--- a/sx127x_lora.cpp Tue Jun 02 01:25:47 2015 +0000
+++ b/sx127x_lora.cpp Tue Jun 02 17:09:19 2015 +0000
@@ -18,11 +18,19 @@
SX127x_lora::SX127x_lora(SX127x& r) : m_xcvr(r)
{
+ if (!m_xcvr.RegOpMode.bits.LongRangeMode)
+ enable();
+
RegModemConfig.octet = m_xcvr.read_reg(REG_LR_MODEMCONFIG);
RegModemConfig2.octet = m_xcvr.read_reg(REG_LR_MODEMCONFIG2);
RegTest31.octet = m_xcvr.read_reg(REG_LR_TEST31);
RegTest33.octet = m_xcvr.read_reg(REG_LR_TEST33); // invert_i_q
RegDriftInvert.octet = m_xcvr.read_reg(REG_LR_DRIFT_INVERT);
+ RegGainDrift.octet = m_xcvr.read_reg(REG_LR_GAIN_DRIFT);
+
+ if (m_xcvr.type == SX1276) {
+ RegAutoDrift.octet = m_xcvr.read_reg(REG_LR_SX1276_AUTO_DRIFT);
+ }
// CRC for TX is disabled by default
setRxPayloadCrcOn(true);
@@ -64,21 +72,9 @@
m_xcvr.RegOpMode.bits.LongRangeMode = 1;
m_xcvr.write_reg(REG_OPMODE, m_xcvr.RegOpMode.octet);
- /*RegOpMode.octet = read_reg(REG_OPMODE);
- printf("setloraon:%02x\r\n", RegOpMode.octet);*/
-
-
- /* // RxDone RxTimeout FhssChangeChannel CadDone
- SX1272LR->RegDioMapping1 = RFLR_DIOMAPPING1_DIO0_00 | RFLR_DIOMAPPING1_DIO1_00 | RFLR_DIOMAPPING1_DIO2_00 | RFLR_DIOMAPPING1_DIO3_00;
- // CadDetected ModeReady
- SX1272LR->RegDioMapping2 = RFLR_DIOMAPPING2_DIO4_00 | RFLR_DIOMAPPING2_DIO5_00;
- SX1272WriteBuffer( REG_LR_DIOMAPPING1, &SX1272LR->RegDioMapping1, 2 );*/
m_xcvr.RegDioMapping1.bits.Dio0Mapping = 0; // DIO0 to RxDone
m_xcvr.RegDioMapping1.bits.Dio1Mapping = 0;
m_xcvr.write_reg(REG_DIOMAPPING1, m_xcvr.RegDioMapping1.octet);
-
- // todo: read LoRa regsiters
- //SX1272ReadBuffer( REG_LR_OPMODE, SX1272Regs + 1, 0x70 - 1 );
m_xcvr.set_opmode(RF_OPMODE_STANDBY);
}
@@ -247,34 +243,13 @@
if (!m_xcvr.RegOpMode.bits.LongRangeMode)
return;
- if (m_xcvr.type == SX1276) {
- RegAutoDrift_t auto_drift;
-
+ if (m_xcvr.type == SX1276) {
RegModemConfig.sx1276bits.Bw = bw;
if (get_symbol_period() > 16)
RegModemConfig3.sx1276bits.LowDataRateOptimize = 1;
else
RegModemConfig3.sx1276bits.LowDataRateOptimize = 0;
- m_xcvr.write_reg(REG_LR_MODEMCONFIG3, RegModemConfig3.octet);
-
- auto_drift.octet = m_xcvr.read_reg(REG_LR_SX1276_AUTO_DRIFT);
- if (bw == 9) { // if 500KHz bw
- RegGainDrift_t gd;
- gd.octet = m_xcvr.read_reg(REG_LR_GAIN_DRIFT);
- auto_drift.bits.freq_to_time_drift_auto = 0;
- if (m_xcvr.HF) {
- // > 525MHz
- gd.bits.freq_to_time_drift = 0x24;
- } else {
- // < 525MHz
- gd.bits.freq_to_time_drift = 0x3f;
- }
- m_xcvr.write_reg(REG_LR_GAIN_DRIFT, gd.octet);
- } else {
- auto_drift.bits.freq_to_time_drift_auto = 1;
- }
- m_xcvr.write_reg(REG_LR_SX1276_AUTO_DRIFT, auto_drift.octet);
-
+ m_xcvr.write_reg(REG_LR_MODEMCONFIG3, RegModemConfig3.octet);
} else if (m_xcvr.type == SX1272) {
RegModemConfig.sx1272bits.Bw = bw;
if (get_symbol_period() > 16)
@@ -306,21 +281,8 @@
void SX127x_lora::setSf(uint8_t sf)
{
if (!m_xcvr.RegOpMode.bits.LongRangeMode)
- return;
-
- // false detections vs missed detections tradeoff
- switch (sf) {
- case 6:
- set_nb_trig_peaks(3);
- break;
- case 7:
- set_nb_trig_peaks(4);
- break;
- default:
- set_nb_trig_peaks(5);
- break;
- }
-
+ return;
+
// write register at 0x37 with value 0xc if at SF6
if (sf < 7)
m_xcvr.write_reg(REG_LR_DETECTION_THRESHOLD, 0x0c);
@@ -434,6 +396,47 @@
if (m_xcvr.RegOpMode.sx1276LORAbits.AccessSharedReg)
return; // fsk page
+ if (m_xcvr.type == SX1276) {
+ if (RegModemConfig.sx1276bits.Bw == 9) { // if 500KHz bw: improved tolerance of reference frequency error
+ if (RegAutoDrift.bits.freq_to_time_drift_auto) {
+ RegAutoDrift.bits.freq_to_time_drift_auto = 0;
+ m_xcvr.write_reg(REG_LR_SX1276_AUTO_DRIFT, RegAutoDrift.octet);
+ }
+ if (m_xcvr.HF) {
+ // > 525MHz
+ if (RegGainDrift.bits.freq_to_time_drift != 0x24) {
+ RegGainDrift.bits.freq_to_time_drift = 0x24;
+ m_xcvr.write_reg(REG_LR_GAIN_DRIFT, RegGainDrift.octet);
+ }
+ } else {
+ // < 525MHz
+ if (RegGainDrift.bits.freq_to_time_drift != 0x3f) {
+ RegGainDrift.bits.freq_to_time_drift = 0x3f;
+ m_xcvr.write_reg(REG_LR_GAIN_DRIFT, RegGainDrift.octet);
+ }
+ }
+
+ } else {
+ if (!RegAutoDrift.bits.freq_to_time_drift_auto) {
+ RegAutoDrift.bits.freq_to_time_drift_auto = 1;
+ m_xcvr.write_reg(REG_LR_SX1276_AUTO_DRIFT, RegAutoDrift.octet);
+ }
+ }
+ } // ... if (m_xcvr.type == SX1276)
+
+ // RX_CONTINUOUS: false detections vs missed detections tradeoff
+ switch (RegModemConfig2.sx1276bits.SpreadingFactor) {
+ case 6:
+ set_nb_trig_peaks(3);
+ break;
+ case 7:
+ set_nb_trig_peaks(4);
+ break;
+ default:
+ set_nb_trig_peaks(5);
+ break;
+ }
+
m_xcvr.set_opmode(RF_OPMODE_RECEIVER);
if (m_xcvr.RegDioMapping1.bits.Dio0Mapping != 0) {