[Generic] Define a default USER_BTN

Allow to build some sketches during CI build.
It can be redefined if needed.

Signed-off-by: Frederic Pillon <frederic.pillon@st.com>

Author: fpistm

variants/Generic_F103Rx/variant.h

@@ -93,6 +93,11 @@ extern "C" {
 #endif
 #define LED_GREEN               LED_BUILTIN
 
+// On-board user button
+#ifndef USER_BTN
+#define USER_BTN                PC13
+#endif
+
 // Override default Arduino configuration
 // SPI Definitions
 #define PIN_SPI_SS              PA4

variants/Generic_F103Zx/variant.h

@@ -153,6 +153,11 @@ extern "C" {
 #define LED_BUILTIN             PC13
 #endif
 
+// On-board user button
+#ifndef USER_BTN
+#define USER_BTN                PB1
+#endif
+
 // SPI Definitions
 #ifdef ARDUINO_VCCGND_F103ZET6
 #define PIN_SPI_SS              PA15

variants/Generic_F411Cx/variant.h

@@ -74,17 +74,15 @@ extern "C" {
 // On-board LED pin number
 #ifdef ARDUINO_BLACKPILL_F411CE
 #define LED_BUILTIN             PC13
-#endif
-#ifndef LED_BUILTIN
+#elif !defined(LED_BUILTIN)
 #define LED_BUILTIN             PA5
 #endif
 #define LED_GREEN               LED_BUILTIN
 
 // On-board user button
 #ifdef ARDUINO_BLACKPILL_F411CE
 #define USER_BTN                PA0
-#endif
-#if !defined(USER_BTN)
+#elif !defined(USER_BTN)
 #define USER_BTN                PC13
 #endif