simtrace: Boot into DFU when BOOTLOADER button is pressed

This recovers the old functionality of the SAM7 based OpenPCD firmware.

firmware/libboard/simtrace/include/board.h

@@ -61,6 +61,7 @@
 #define PINS_USIM1		PIN_PHONE_IO, PIN_PHONE_CLK, PIN_PHONE_CLK_INPUT, PIN_USIM1_VCC, PIN_PHONE_IO_INPUT, PIN_USIM1_nRST
 //, VCC_PHONE
 
+#define PIN_BOOTLOADER_SW	{PIO_PA31, PIOA, ID_PIOA, PIO_INPUT,  PIO_PULLUP}
 
 //**     SPI interface   **/
 /// SPI MISO pin definition (PA12).

firmware/libboard/simtrace/source/board_simtrace.c

@@ -35,3 +35,17 @@ void board_main_top(void)
 	//card_present_init();
 #endif
 }
+
+int board_override_enter_dfu(void)
+{
+	const Pin bl_sw_pin = PIN_BOOTLOADER_SW;
+
+	PIO_Configure(&bl_sw_pin, 1);
+
+	/* Enter DFU bootloader in case the respective button is pressed */
+	if (PIO_Get(&bl_sw_pin) == 0) {
+		//printf("BOOTLOADER switch presssed -> Force DFU\n\r");
+		return 1;
+	} else
+		return 0;
+}