GPS support added (experimental)

src/hal/ttgobeam.h

@@ -3,11 +3,10 @@
 #define CFG_sx1276_radio 1 // HPD13A LoRa SoC
 
 #define HAS_LED 21 // on board green LED_G1
-#define HAS_BUTTON GPIO_NUM_39 // button on board next to battery indicator LED (other one is reset)
+#define HAS_BUTTON GPIO_NUM_0 // on board button "BOOT" (next to reset button)
 #define HAS_BATTERY_PROBE ADC1_GPIO35_CHANNEL // battery probe GPIO pin -> ADC1_CHANNEL_7
 #define BATT_FACTOR 2 // voltage divider 100k/100k on board
-// #define HAS_GPS // to be done
-// GSP serial (9600, SERIAL_8N1, 12, 15);   //17-TX 18-RX
+#define HAS_GPS 9600, SERIAL_8N1, 12, 15   //17-TX 18-RX
 
 // re-define pin definitions of pins_arduino.h
 #define PIN_SPI_SS    18 // ESP32 GPIO18 (Pin18) -- HPD13A NSS/SEL (Pin4) SPI Chip Select Input