Set some unspecified pins to -1

Author: matthias-bs

variants/thingpulse_epulse_feather/pins_arduino.h

@@ -3,12 +3,17 @@
 
 #include <stdint.h>
 
+static const uint8_t LED_BUILTIN = -1;
+#define BUILTIN_LED  LED_BUILTIN // backward compatibility
+#define LED_BUILTIN LED_BUILTIN  // allow testing #ifdef LED_BUILTIN
+
 static const uint8_t SDA = 23;
 static const uint8_t SCL = 22;
 
 static const uint8_t MOSI  = 18;
 static const uint8_t MISO  = 19;
 static const uint8_t SCK   = 5;
+static const uint8_t SS    = -1;
 
 // mapping to match other feathers and also in order
 static const uint8_t A0 = 26;