If there is no application in FLASH, or flash was corrupted, make sure to restart in DFU mode

src/main.c

@@ -48,7 +48,10 @@
 #include "nrf_soc.h"
 #include "nrf_nvic.h"
 #include "app_error.h"
+#include "nrf_gpio.h"
 #include "ble.h"
+#include "nrf.h"
+#include "ble_hci.h"
 #include "app_scheduler.h"
 #include "nrf_error.h"
 
@@ -56,10 +59,13 @@
 
 #include "pstorage_platform.h"
 #include "nrf_mbr.h"
+#include "pstorage.h"
+#include "nrfx_nvmc.h"
 
 #ifdef NRF_USBD
 
 #include "uf2/uf2.h"
+#include "nrf_usbd.h"
 #include "tusb.h"
 
 void usb_init(bool cdc_only);
@@ -218,6 +224,9 @@ int main(void) {
     bootloader_app_start();
   }
 
+  // No application was loaded, reset the system with the OTA DFU update
+  NRF_POWER->GPREGRET = 0xA8; 
+  
   NVIC_SystemReset();
 }
 
@@ -242,17 +251,14 @@ static void check_dfu_mode(void) {
                    (((*dbl_reset_mem) == DFU_DBL_RESET_MAGIC) && reason_reset_pin);
 
   // Clear GPREGRET if it is our values
-  if (dfu_start || dfu_skip) {
-    NRF_POWER->GPREGRET = 0;
-  }
+  if (dfu_start || dfu_skip) NRF_POWER->GPREGRET = 0;
 
   // skip dfu entirely
-  if (dfu_skip) {
-    return;
-  }
+  if (dfu_skip) return;
 
   /*------------- Determine DFU mode (Serial, OTA, FRESET or normal) -------------*/
-  dfu_start = dfu_start || button_pressed(BUTTON_DFU); // DFU button pressed
+  // DFU button pressed
+  dfu_start = dfu_start || button_pressed(BUTTON_DFU);
 
   // DFU + FRESET are pressed --> OTA
   _ota_dfu = _ota_dfu || (button_pressed(BUTTON_DFU) && button_pressed(BUTTON_FRESET));
@@ -260,16 +266,16 @@ static void check_dfu_mode(void) {
   bool const valid_app = bootloader_app_is_valid();
   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;
-  }
+  if (!just_start_app && APP_ASKS_FOR_SINGLE_TAP_RESET()) dfu_start = 1;
 
   // App mode: Double Reset detection or DFU startup for nrf52832
   if (!(just_start_app || dfu_start || !valid_app)) {
 #ifdef NRF52832_XXAA
     /* Even DFU is not active, we still force an 1000 ms dfu serial mode when startup
      * to support auto programming from Arduino IDE
-     * Note: Double Reset WONT work with nrf52832 since all its SRAM got cleared with GPIO reset. */
+     *
+     * Note: Double Reset WONT work with nrf52832 since all its SRAM got cleared with GPIO reset.
+     */
     bootloader_dfu_start(false, DFU_SERIAL_STARTUP_INTERVAL, false);
 #else
     // Note: RESETREAS is not clear by bootloader, it should be cleared by application upon init()