Allow for single-tap reset when requested

Author: mmoskal

src/main.c

@@ -61,6 +61,7 @@
 #include "nrf_error.h"
 
 #include "boards.h"
+#include "uf2/uf2.h"
 
 #include "pstorage_platform.h"
 #include "nrf_mbr.h"
@@ -112,6 +113,8 @@ void usb_teardown(void);
 #define BOOTLOADER_VERSION_REGISTER     NRF_TIMER2->CC[0]
 #define DFU_SERIAL_STARTUP_INTERVAL     1000
 
+#define APP_ASKS_FOR_SINGLE_TAP_RESET() (*((uint32_t*)(USER_FLASH_START + 0x200)) == 0x87eeb07c)
+
 // These value must be the same with one in dfu_transport_ble.c
 #define BLEGAP_EVENT_LENGTH             6
 #define BLEGATT_ATT_MTU_MAX             247
@@ -200,6 +203,9 @@ int main(void)
   bool const valid_app = bootloader_app_is_valid(DFU_BANK_0_REGION_START);
   bool const just_start_app = valid_app && !dfu_start && (*dbl_reset_mem) == DFU_DBL_RESET_APP;
 
+  if (!just_start_app && APP_ASKS_FOR_SINGLE_TAP_RESET())
+    dfu_start = 1;
+
   // App mode: register 1st reset and DFU startup (nrf52832)
   if ( ! (just_start_app || dfu_start || !valid_app) )
   {
@@ -220,7 +226,10 @@ int main(void)
 #endif
   }
 
-  (*dbl_reset_mem) = 0;
+  if (APP_ASKS_FOR_SINGLE_TAP_RESET())
+    (*dbl_reset_mem) = DFU_DBL_RESET_APP;
+  else
+    (*dbl_reset_mem) = 0;
 
   if ( dfu_start || !valid_app )
   {
@@ -263,6 +272,9 @@ int main(void)
     // MBR must be init before start application
     if ( !sd_inited ) softdev_mbr_init();
 
+    // clear in case we kept DFU_DBL_RESET_APP there
+    (*dbl_reset_mem) = 0;
+
     // Select a bank region to use as application region.
     // @note: Only applications running from DFU_BANK_0_REGION_START is supported.
     bootloader_app_start(DFU_BANK_0_REGION_START);