add vbat for metro, clean up

Author: hathach

libraries/Bluefruit52Lib/examples/Hardware/adc_vbat/adc_vbat.ino

@@ -1,12 +1,13 @@
+#include <Arduino.h>
+
+uint32_t vbat_pin = PIN_VBAT;             // A7 for feather nRF52832, A6 for nRF52840
 
 #define VBAT_MV_PER_LSB   (0.73242188F)   // 3.0V ADC range and 12-bit ADC resolution = 3000mV/4096
 
 #ifdef NRF52840_XXAA    // if this is for nrf52840
-#define VBAT_PIN (A6)
-#define VBAT_DIVIDER (0.5F)               // 150K + 150K voltage divider on VBAT
+#define VBAT_DIVIDER      (0.5F)               // 150K + 150K voltage divider on VBAT
 #define VBAT_DIVIDER_COMP (2.0F)          // Compensation factor for the VBAT divider
 #else
-#define VBAT_PIN          (A7)
 #define VBAT_DIVIDER      (0.71275837F)   // 2M + 0.806M voltage divider on VBAT = (2M / (0.806M + 2M))
 #define VBAT_DIVIDER_COMP (1.403F)        // Compensation factor for the VBAT divider
 #endif
@@ -27,7 +28,7 @@ float readVBAT(void) {
   delay(1);
 
   // Get the raw 12-bit, 0..3000mV ADC value
-  raw = analogRead(VBAT_PIN);
+  raw = analogRead(vbat_pin);
 
   // Set the ADC back to the default settings
   analogReference(AR_DEFAULT);

variants/feather_nrf52840_express/variant.h

@@ -86,7 +86,7 @@ static const uint8_t A7  = PIN_A7 ;
 #define ADC_RESOLUTION    14
 
 // Other pins
-#define PIN_AREF           (PIN_A7)
+#define PIN_AREF           PIN_A7
 #define PIN_VBAT           PIN_A6
 #define PIN_NFC1           (33)
 #define PIN_NFC2           (2)

variants/metro_nrf52840_express/variant.h

@@ -86,7 +86,8 @@ static const uint8_t A7  = PIN_A7 ;
 #define ADC_RESOLUTION    14
 
 // Other pins
-#define PIN_AREF           (PIN_A7)
+#define PIN_AREF           PIN_A7
+#define PIN_VBAT           PIN_A6
 #define PIN_NFC1           (2)
 #define PIN_NFC2           (51)