SX126x: Try next Interface when chip not found (#2363)

* If chip was not found, return false for init()

* SX1268: Only overwrite frequency when out of bounds
Happens when region is still UNSET

src/mesh/SX1268Interface.cpp

@@ -6,4 +6,13 @@ SX1268Interface::SX1268Interface(RADIOLIB_PIN_TYPE cs, RADIOLIB_PIN_TYPE irq, RA
                                  SPIClass &spi)
     : SX126xInterface(cs, irq, rst, busy, spi)
 {
+}
+
+float SX1268Interface::getFreq()
+{
+    // Set frequency to default of EU_433 if outside of allowed range (e.g. when region is UNSET)
+    if (savedFreq < 410 || savedFreq > 810)
+        return 433.125f;
+    else
+        return savedFreq;
 }

src/mesh/SX1268Interface.h

@@ -8,8 +8,7 @@
 class SX1268Interface : public SX126xInterface<SX1268>
 {
   public:
-    /// override frequency of the SX1268 module regardless of the region (use EU433 value)
-    virtual float getFreq() override { return 433.175f; }
+    virtual float getFreq() override;
 
     SX1268Interface(RADIOLIB_PIN_TYPE cs, RADIOLIB_PIN_TYPE irq, RADIOLIB_PIN_TYPE rst, RADIOLIB_PIN_TYPE busy, SPIClass &spi);
 };

src/mesh/SX126xInterface.cpp

@@ -47,6 +47,8 @@ template <typename T> bool SX126xInterface<T>::init()
     int res = lora.begin(getFreq(), bw, sf, cr, syncWord, power, preambleLength, tcxoVoltage, useRegulatorLDO);
     // \todo Display actual typename of the adapter, not just `SX126x`
     LOG_INFO("SX126x init result %d\n", res);
+    if (res == RADIOLIB_ERR_CHIP_NOT_FOUND)
+        return false;
 
     LOG_INFO("Frequency set to %f\n", getFreq());
     LOG_INFO("Bandwidth set to %f\n", bw);