sx127x 20dBm support (#153)

Author: dontsovcmc

API.md

@@ -249,7 +249,7 @@ LoRa.setTxPower(txPower, outputPin);
  * `txPower` - TX power in dB, defaults to `17`
  * `outputPin` - (optional) PA output pin, supported values are `PA_OUTPUT_RFO_PIN` and `PA_OUTPUT_PA_BOOST_PIN`, defaults to `PA_OUTPUT_PA_BOOST_PIN`.
 
-Supported values are between `2` and `17` for `PA_OUTPUT_PA_BOOST_PIN`, `0` and `14` for `PA_OUTPUT_RFO_PIN`.
+Supported values are `2` to `20` for `PA_OUTPUT_PA_BOOST_PIN`, and `0` to `14` for `PA_OUTPUT_RFO_PIN`.
 
 Most modules have the PA output pin connected to PA BOOST,
 

src/LoRa.cpp

@@ -10,6 +10,7 @@
 #define REG_FRF_MID              0x07
 #define REG_FRF_LSB              0x08
 #define REG_PA_CONFIG            0x09
+#define REG_OCP                  0x0b
 #define REG_LNA                  0x0c
 #define REG_FIFO_ADDR_PTR        0x0d
 #define REG_FIFO_TX_BASE_ADDR    0x0e
@@ -34,6 +35,7 @@
 #define REG_SYNC_WORD            0x39
 #define REG_DIO_MAPPING_1        0x40
 #define REG_VERSION              0x42
+#define REG_PA_DAC               0x4d
 
 // modes
 #define MODE_LONG_RANGE_MODE     0x80
@@ -372,10 +374,24 @@ void LoRaClass::setTxPower(int level, int outputPin)
     writeRegister(REG_PA_CONFIG, 0x70 | level);
   } else {
     // PA BOOST
-    if (level < 2) {
-      level = 2;
-    } else if (level > 17) {
-      level = 17;
+    if (level > 17) {
+      if (level > 20) {
+        level = 20;
+      }
+
+      // subtract 3 from level, so 18 - 20 maps to 15 - 17
+      level -= 3;
+
+      // High Power +20 dBm Operation (Semtech SX1276/77/78/79 5.4.3.)
+      writeRegister(REG_PA_DAC, 0x87);
+      setOCP(140);
+    } else {
+      if (level < 2) {
+        level = 2;
+      }
+      //Default value PA_HF/LF or +17dBm
+      writeRegister(REG_PA_DAC, 0x84); 
+      setOCP(100);
     }
 
     writeRegister(REG_PA_CONFIG, PA_BOOST | (level - 2));
@@ -512,6 +528,19 @@ void LoRaClass::disableCrc()
   writeRegister(REG_MODEM_CONFIG_2, readRegister(REG_MODEM_CONFIG_2) & 0xfb);
 }
 
+void LoRaClass::setOCP(uint8_t mA)
+{
+  uint8_t ocpTrim = 27;
+
+  if (mA <= 120) {
+    ocpTrim = (mA - 45) / 5;
+  } else if (mA <=240) {
+    ocpTrim = (mA + 30) / 10;
+  }
+
+  writeRegister(REG_OCP, 0x20 | (0x1F & ocpTrim));        
+}
+
 byte LoRaClass::random()
 {
   return readRegister(REG_RSSI_WIDEBAND);

src/LoRa.h

@@ -66,6 +66,7 @@ class LoRaClass : public Stream {
   void setSyncWord(int sw);
   void enableCrc();
   void disableCrc();
+  void setOCP(uint8_t mA); // Over Current Protection control
 
   // deprecated
   void crc() { enableCrc(); }