[CC1101] 3 New CC1101 Functions (#1038)

* getFrequency implementation

* getFrequency Method

* Get bitrate method

* getBitRate

* CalcRxBandwidth() method

* CalcRxBandwidth();

* Fix Notes

* Changes for pull

* Changes for pull 2

* Update keywords.txt

* Revert to hopefully bring in current

* Fix ()

* Re add

keywords.txt

@@ -134,6 +134,7 @@ getSNR	KEYWORD2
 getDataRate	KEYWORD2
 setBitRate	KEYWORD2
 setRxBandwidth	KEYWORD2
+autoSetRxBandwidth	KEYWORD2
 setAFCBandwidth	KEYWORD2
 setAFC		KEYWORD2
 setAFCAGCTrigger	KEYWORD2

src/modules/CC1101/CC1101.cpp

@@ -489,6 +489,24 @@ int16_t CC1101::setRxBandwidth(float rxBw) {
   return(RADIOLIB_ERR_INVALID_RX_BANDWIDTH);
 }
 
+int16_t CC1101::autoSetRxBandwidth() {
+    // Uncertainty ~ +/- 40ppm for a cheap CC1101
+    // Uncertainty * 2 for both transmitter and receiver
+    float uncertainty = ((this->frequency) * 40 * 2);
+    uncertainty = (uncertainty/1000); //Since bitrate is in kBit
+    float minbw = ((this->bitRate) + uncertainty);
+    
+    int possibles[16] = {58, 68, 81, 102, 116, 135, 162, 203, 232, 270, 325, 406, 464, 541, 650, 812};
+    
+    for (int i = 0; i < 16; i++) {
+      if (possibles[i] > minbw) {
+        int16_t state = setRxBandwidth(possibles[i]);
+        return(state);
+      }
+    }
+    return(RADIOLIB_ERR_UNKNOWN);
+  }
+
 int16_t CC1101::setFrequencyDeviation(float freqDev) {
   // set frequency deviation to lowest available setting (required for digimodes)
   float newFreqDev = freqDev;

src/modules/CC1101/CC1101.h

@@ -745,6 +745,14 @@ class CC1101: public PhysicalLayer {
     */
     int16_t setRxBandwidth(float rxBw);
 
+     /*!
+      \brief calculates and sets Rx bandwidth based on the freq, baud and freq uncertainty.
+      Reimplement of atlas0fd00m's (RfCat) CalculatePktChanBw function. 
+      Modified for worse ppm with the CC1101, and adjusted for the supportted CC1101 bw.
+      \returns \ref status_codes
+    */
+    int16_t autoSetRxBandwidth();
+
     /*!
       \brief Sets frequency deviation. Allowed values range from 1.587 to 380.8 kHz.
       \param freqDev Frequency deviation to be set in kHz.