Update changelog.md

Resolve OTA failure with bond shared from application

.github/workflows/githubci.yml

@@ -24,7 +24,7 @@ jobs:
           - 'itsybitsy_nrf52840_express'
           - 'metro_nrf52840_express'
           # Alphabetical order
-          - 'ADM_B_NRF52840_1'
+          - 'adm_b_nrf52840_1'
           - 'ae_bl652_bo'
           - 'aramcon_badge_2019'
           - 'arcade_feather_nrf52840_express'
@@ -45,6 +45,7 @@ jobs:
           - 'pca10100'
           - 'pitaya_go'
           - 'raytac_mdbt50q_rx'
+          - 'sparkfun_nrf52840_micromod'
           - 'waveshare_nrf52840_eval'
 
     steps:
@@ -66,7 +67,7 @@ jobs:
         # 9.3.1-1.2.1 is xpack modified version which significantly increased compiled size to 6-7KB and cause flash overflow.
         # Skip this version for now, we will try again with next official release from ARM
         xpm install --global @xpack-dev-tools/arm-none-eabi-gcc@9.3.1-1.1.1
-        echo `echo $HOME/opt/xPacks/@xpack-dev-tools/arm-none-eabi-gcc/*/.content/bin` >> $GITHUB_PATH
+        echo `echo $HOME/.local/xPacks/@xpack-dev-tools/arm-none-eabi-gcc/*/.content/bin` >> $GITHUB_PATH
     
     - name: Build
       run: |
@@ -78,12 +79,11 @@ jobs:
         name: ${{ matrix.board }}
         path: _bin/${{ matrix.board }}
 
-    - name: Creat Release Asset
+    - name: Create Release Asset
       if: ${{ github.event_name == 'release' }}
       run: zip -jr ${{ matrix.board }}_bootloader-${{ github.event.release.tag_name }}.zip _bin/${{ matrix.board }}
 
     - name: Upload Release Asset
-      id: upload-release-asset
       uses: actions/upload-release-asset@v1
       env:
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
@@ -94,3 +94,13 @@ jobs:
         asset_name: ${{ matrix.board }}_bootloader-${{ github.event.release.tag_name }}.zip
         asset_content_type: application/zip
       
+    - name: Upload Release Asset for Self-Update
+      uses: actions/upload-release-asset@v1
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      if: ${{ github.event_name == 'release' }}
+      with:
+        upload_url: ${{ github.event.release.upload_url }}
+        asset_path: _bin/${{ matrix.board }}/update-${{ matrix.board }}_bootloader-${{ github.event.release.tag_name }}_nosd.uf2
+        asset_name: update-${{ matrix.board }}_bootloader-${{ github.event.release.tag_name }}_nosd.uf2
+        asset_content_type: application/x-binary

README.md

@@ -20,6 +20,7 @@ This is a CDC/DFU/UF2 bootloader for nRF52 boards.
 - Particle Argon
 - Particle Boron
 - Particle Xenon
+- [SparkFun MicroMod nRF52840](https://www.sparkfun.com/products/16984)
 
 UF2 is an easy-to-use bootloader that appears as a flash drive. You can just copy `.uf2`-format
 application images to the flash drive to load new firmware. See https://github.com/Microsoft/uf2 and https://github.com/adafruit/uf2-samdx1 for more information.
@@ -57,6 +58,14 @@ There are two pins, `DFU` and `FRST` that bootloader will check upon reset/power
 - The `GPREGRET` register can also be set to force the bootloader can enter any of above modes (plus a CDC-only mode for Arduino).
 `GPREGRET` is set by the application before performing a soft reset.
 
+```c
+#include "nrf_nvic.h"
+void reset_to_uf2(void) {
+  NRF_POWER->GPREGRET = 0x57; // 0xA8 OTA, 0x4e Serial
+  NVIC_SystemReset();         // or sd_nvic_SystemReset();
+}
+```
+
 On the Nordic PCA10056 DK board, `DFU` is connected to **Button1**, and `FRST` is connected to **Button2**.
 So holding down **Button1** while clicking **RESET** will put the board into USB bootloader mode, with UF2 and CDC support.
 Holding down **Button2** while clicking **RESET** will put the board into OTA (over-the-air) bootloader mode.
@@ -69,7 +78,7 @@ For other boards, please check the board definition for details.
 
 ### Making your own UF2
 
-To create your own UF2 DFU update image, simply use the [Python conversion script](https://github.com/Microsoft/uf2/blob/master/utils/uf2conv.py) on a .bin file or .hex file, specifying the family as **0xADA52840**. If using a .bin file with the conversion script you must specify application address with the -b switch, this address depend on the SoftDevice size/version e.g S140 v6 is 0x26000 
+To create your own UF2 DFU update image, simply use the [Python conversion script](https://github.com/Microsoft/uf2/blob/master/utils/uf2conv.py) on a .bin file or .hex file, specifying the family as **0xADA52840**. If using a .bin file with the conversion script you must specify application address with the -b switch, this address depend on the SoftDevice size/version e.g S140 v6 is 0x26000
 
 To create a UF2 image from a .bin file:
 ```
@@ -105,6 +114,15 @@ You must have have a J-Link available to "unbrick" your device.
 Prerequisites
 
 - ARM GCC
+
+To install for macos
+
+```bash
+brew tap ArmMbed/homebrew-formulae
+brew install arm-none-eabi-gcc
+brew link --overwrite arm-none-eabi-gcc # if a prior version was present
+```
+
 - Nordic's [nRF5x Command Line Tools](https://www.nordicsemi.com/Software-and-Tools/Development-Tools/nRF-Command-Line-Tools)
 - [Python IntelHex](https://pypi.org/project/IntelHex/)
 
@@ -148,7 +166,7 @@ Makefile:90: *** BOARD not defined.  Stop
 If you get the following error ...
 
 ```
-$ make BOARD=feather_nrf52840_express all 
+$ make BOARD=feather_nrf52840_express all
 Compiling file: main.c
 /bin/sh: /usr/bin/arm-none-eabi-gcc: No such file or directory
 make: *** [_build/main.o] Error 127
@@ -160,6 +178,8 @@ the variable `CROSS_COMPILE` as below:
 $ make CROSS_COMPILE=/opt/gcc-arm-none-eabi-9-2019-q4-major/bin/arm-none-eabi- BOARD=feather_nrf52832 all
 ```
 
+For other compile errors, check the gcc version with `arm-none-eabi-gcc --version` to insure it is at least 9.x.
+
 #### 2. `ModuleNotFoundError: No module named 'intelhex'`
 
 Install python-intelhex with
@@ -169,9 +189,6 @@ pip install intelhex
 ```
 
 
-
-
-
 #### 3. `make: nrfjprog: No such file or directory`
 
 Make sure that `nrfjprog` is available from the command-line. This binary is

changelog.md

@@ -1,5 +1,18 @@
 # Adafruit nRF52 Bootloader Changelog
 
+## 0.5.0 - 2021.04.04
+
+- Update tinyusb to latest to fix the race condition causing cdc out dropping packet. Which cause DFU failed occasionally
+- Add support for Dotstar LED (APA102)
+- Add sparkfun_nrf52840_micromod board
+- Allow skipping DFU entirely when reset or wakeup from deep sleep
+- Fix an issue with OTA when using shared bond with application
+
+## 0.4.1 - 2021.02.17
+
+- Add USB connect timeout for app reset to UF2 or Serial via GPREGRET
+- Fix pollution of REGOUT0 reserved bits
+
 ## 0.4.0 - 2021.01.19
 
 - Decouple bootloader and softdevice i.e bootloader will always work with and/or without softdevice present. This allows application to pack firmware + softdevice into an uf2/serial for DFU.

lib/sdk11/components/libraries/bootloader_dfu/dfu_transport_ble.c

@@ -148,6 +148,7 @@ static uint32_t service_change_indicate()
 
         err_code = sd_ble_gatts_service_changed(m_conn_handle, DFU_SERVICE_HANDLE, BLE_HANDLE_MAX);
         if ((err_code == BLE_ERROR_INVALID_CONN_HANDLE) ||
+            (err_code == BLE_ERROR_INVALID_ATTR_HANDLE) ||
             (err_code == NRF_ERROR_INVALID_STATE) ||
             (err_code == NRF_ERROR_BUSY))
         {

src/boards/boards.c

@@ -27,13 +27,17 @@
 #include "app_scheduler.h"
 #include "app_timer.h"
 
+#ifdef LED_APA102
+#include "nrf_spim.h"
+#endif
+
 //--------------------------------------------------------------------+
 // MACRO TYPEDEF CONSTANT ENUM DECLARATION
 //--------------------------------------------------------------------+
 #define SCHED_MAX_EVENT_DATA_SIZE           sizeof(app_timer_event_t)        /**< Maximum size of scheduler events. */
 #define SCHED_QUEUE_SIZE                    30                               /**< Maximum number of events in the scheduler queue. */
 
-#if defined(LED_NEOPIXEL) || defined(LED_RGB_RED_PIN)
+#if defined(LED_NEOPIXEL) || defined(LED_RGB_RED_PIN) || defined(LED_APA102)
   void neopixel_init(void);
   void neopixel_write(uint8_t *pixels);
   void neopixel_teardown(void);
@@ -71,14 +75,15 @@ void board_init(void)
   button_init(BUTTON_FRESET);
   NRFX_DELAY_US(100); // wait for the pin state is stable
 
+#if LEDS_NUMBER > 0
   // use PMW0 for LED RED
   led_pwm_init(LED_PRIMARY, LED_PRIMARY_PIN);
   #if LEDS_NUMBER > 1
   led_pwm_init(LED_SECONDARY, LED_SECONDARY_PIN);
   #endif
-
+#endif
   // use neopixel for use enumeration
-#if defined(LED_NEOPIXEL) || defined(LED_RGB_RED_PIN)
+#if defined(LED_NEOPIXEL) || defined(LED_RGB_RED_PIN) || defined(LED_APA102)
   neopixel_init();
 #endif
 
@@ -94,11 +99,13 @@ void board_init(void)
 //     #define UICR_REGOUT0_VALUE UICR_REGOUT0_VOUT_3V3
 // in board.h when using that power configuration.
 #ifdef UICR_REGOUT0_VALUE
-  if (NRF_UICR->REGOUT0 != UICR_REGOUT0_VALUE) 
+  if ((NRF_UICR->REGOUT0 & UICR_REGOUT0_VOUT_Msk) !=
+      (UICR_REGOUT0_VALUE << UICR_REGOUT0_VOUT_Pos))
   {
       NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen << NVMC_CONFIG_WEN_Pos;
       while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
-      NRF_UICR->REGOUT0 = UICR_REGOUT0_VALUE;
+      NRF_UICR->REGOUT0 = (NRF_UICR->REGOUT0 & ~((uint32_t)UICR_REGOUT0_VOUT_Msk)) |
+                          (UICR_REGOUT0_VALUE << UICR_REGOUT0_VOUT_Pos);
 
       NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos;
       while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
@@ -124,9 +131,11 @@ void board_teardown(void)
   SysTick->CTRL = 0;
 
   // Disable and reset PWM for LEDs
+#if LEDS_NUMBER > 0
   led_pwm_teardown();
+#endif
 
-#if defined(LED_NEOPIXEL) || defined(LED_RGB_RED_PIN)
+#if defined(LED_NEOPIXEL) || defined(LED_RGB_RED_PIN) || defined(LED_APA102)
   neopixel_teardown();
 #endif
 
@@ -315,7 +324,7 @@ void led_state(uint32_t state)
     } else if (temp_color_active) {
         final_color = (uint8_t*)&rgb_color;
     }
-    #if defined(LED_NEOPIXEL) || defined(LED_RGB_RED_PIN)
+    #if defined(LED_NEOPIXEL) || defined(LED_RGB_RED_PIN) || defined(LED_APA102)
     if (final_color != NULL) {
         neopixel_write(final_color);
     }
@@ -430,6 +439,90 @@ void neopixel_write (uint8_t *pixels)
 }
 #endif
 
+#ifdef LED_APA102
+#define BYTE_PER_PIXEL  4
+
+// 4 zero bytes are required to initiate update
+#define PATTERN_SIZE() ((APA102_NUMBER*BYTE_PER_PIXEL) + 4)
+// N/2 * 1 bits are required at the end
+static uint8_t pixels_pattern[PATTERN_SIZE() + 4];
+
+// use SPIM1 for dotstar
+void neopixel_init(void)
+{
+  NRF_SPIM_Type* spi = NRF_SPIM1;
+
+  nrf_spim_disable(spi);
+
+  nrf_gpio_pin_set(LED_APA102_CLK);
+
+  nrf_gpio_cfg(LED_APA102_CLK,
+                NRF_GPIO_PIN_DIR_OUTPUT,
+                NRF_GPIO_PIN_INPUT_CONNECT,
+                NRF_GPIO_PIN_NOPULL,
+                NRF_GPIO_PIN_S0S1,
+                NRF_GPIO_PIN_NOSENSE);
+
+  nrf_gpio_pin_clear(LED_APA102_DATA);
+  nrf_gpio_cfg_output(LED_APA102_DATA);
+
+  nrf_spim_pins_set(spi, LED_APA102_CLK, LED_APA102_DATA, 0xFFFFFFFF);
+  nrf_spim_frequency_set(spi, NRF_SPIM_FREQ_4M);
+  nrf_spim_configure(spi, NRF_SPIM_MODE_3, NRF_SPIM_BIT_ORDER_MSB_FIRST);
+
+  nrf_spim_orc_set(spi, 0);
+  nrf_spim_tx_list_disable(spi);
+
+  // Enable the spi
+  nrf_spim_enable(spi);
+
+  uint8_t rgb[3] = {0, 0, 0 };
+  neopixel_write(rgb);
+}
+
+void neopixel_teardown(void)
+{
+  uint8_t rgb[3] = {0, 0, 0 };
+  neopixel_write(rgb);
+
+  NRF_SPIM_Type* spi = NRF_SPIM1;
+  nrf_spim_disable(spi);
+}
+
+// write 3 bytes color RGB to built-in neopixel
+void neopixel_write (uint8_t *pixels)
+{
+  NRF_SPIM_Type*  spi = NRF_SPIM1;
+
+  //brightness, blue, green, red
+  uint8_t bbgr[BYTE_PER_PIXEL] = {0xE0 | LED_APA102_BRIGHTNESS, pixels[0], pixels[1], pixels[2]};
+  pixels_pattern[0] = 0;
+  pixels_pattern[1] = 0;
+  pixels_pattern[2] = 0;
+  pixels_pattern[3] = 0;
+
+  for (uint8_t i = 4; i < PATTERN_SIZE(); i+=4) {
+      pixels_pattern[i] = bbgr[0];
+      pixels_pattern[i+1] = bbgr[1];
+      pixels_pattern[i+2] = bbgr[2];
+      pixels_pattern[i+3] = bbgr[3];
+  }
+
+  pixels_pattern[PATTERN_SIZE()] = 0xff;
+  pixels_pattern[PATTERN_SIZE()+1] = 0xff;
+  pixels_pattern[PATTERN_SIZE()+2] = 0xff;
+  pixels_pattern[PATTERN_SIZE()+3] = 0xff;
+
+  nrf_spim_tx_buffer_set(spi, pixels_pattern, PATTERN_SIZE() + 4);
+  nrf_spim_event_clear(spi, NRF_SPIM_EVENT_ENDTX);
+
+  nrf_spim_task_trigger(spi, NRF_SPIM_TASK_START);
+
+  while(!nrf_spim_event_check(spi, NRF_SPIM_EVENT_ENDTX));
+}
+#endif
+
+
 #if defined(LED_RGB_RED_PIN) && defined(LED_RGB_GREEN_PIN) && defined(LED_RGB_BLUE_PIN)
 
 #ifdef LED_SECONDARY_PIN

src/boards/sparkfun_nrf52840_micromod/board.h

@@ -0,0 +1,66 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Ha Thach for Adafruit Industries
+ * Copyright (c) 2021 Chris Marc Dailey
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef _SPARKFUN_NRF52840_MICROMOD_H_
+#define _SPARKFUN_NRF52840_MICROMOD_H_
+
+#define _PINNUM(port, pin)    ((port)*32 + (pin))
+
+/*------------------------------------------------------------------*/
+/* LED
+ *------------------------------------------------------------------*/
+#define LEDS_NUMBER           1
+#define LED_PRIMARY_PIN       _PINNUM(0, 13)
+#define LED_STATE_ON          1
+
+/*------------------------------------------------------------------*/
+/* BUTTON
+ *------------------------------------------------------------------*/
+#define BUTTONS_NUMBER        2
+#define BUTTON_1              _PINNUM(0, 7)
+#define BUTTON_2              _PINNUM(0, 10)
+#define BUTTON_PULL           NRF_GPIO_PIN_PULLUP
+
+//--------------------------------------------------------------------+
+// BLE OTA
+//--------------------------------------------------------------------+
+#define BLEDIS_MANUFACTURER   "SparkFun"
+#define BLEDIS_MODEL          "MicroMod nRF52840"
+
+//--------------------------------------------------------------------+
+// USB
+//--------------------------------------------------------------------+
+#define USB_DESC_VID           0x1B4F
+#define USB_DESC_UF2_PID       0x0022
+#define USB_DESC_CDC_ONLY_PID  0x0023
+
+//------------- UF2 -------------//
+#define UF2_PRODUCT_NAME       "SparkFun MicroMod nRF52840"
+#define UF2_VOLUME_LABEL       "SFMM852BOOT"
+#define UF2_BOARD_ID           "nRF52840-micromod-v10"
+
+#define UF2_INDEX_URL          "https://www.sparkfun.com/products/16984"
+
+#endif /* _SPARKFUN_NRF52840_MICROMOD_H_ */

src/boards/sparkfun_nrf52840_micromod/board.mk

@@ -0,0 +1 @@
+MCU_SUB_VARIANT = nrf52840

src/boards/sparkfun_nrf52840_micromod/pinconfig.c

@@ -0,0 +1,19 @@
+#include "boards.h"
+#include "uf2/configkeys.h"
+
+__attribute__((used, section(".bootloaderConfig")))
+const uint32_t bootloaderConfig[] =
+{
+  /* CF2 START */
+  CFG_MAGIC0, CFG_MAGIC1,                       // magic
+  5, 100,                                       // used entries, total entries
+
+  204, 0x100000,                                // FLASH_BYTES = 0x100000
+  205, 0x40000,                                 // RAM_BYTES = 0x40000
+  208, (USB_DESC_VID << 16) | USB_DESC_UF2_PID, // BOOTLOADER_BOARD_ID = USB VID+PID, used for verification when updating bootloader via uf2
+  209, 0xada52840,                              // UF2_FAMILY = 0xada52840
+  210, 0x20,                                    // PINS_PORT_SIZE = PA_32
+
+  0, 0, 0, 0, 0, 0, 0, 0
+  /* CF2 END */
+};

src/main.c

@@ -97,18 +97,20 @@ void usb_teardown(void);
  */
 
 /* Magic that written to NRF_POWER->GPREGRET by application when it wish to go into DFU
- * - DFU_MAGIC_OTA_APPJUM used by BLEDfu service : SD is already init
- * - DFU_MAGIC_OTA_RESET entered by soft reset : SD is not init
- * - DFU_MAGIC_SERIAL_ONLY_RESET with CDC interface only
- * - DFU_MAGIC_UF2_RESET with CDC and MSC interfaces
+ * - DFU_MAGIC_OTA_APPJUM        : used by BLEDfu service, SD is already inited
+ * - DFU_MAGIC_OTA_RESET         : entered by soft reset, SD is not inited yet
+ * - DFU_MAGIC_SERIAL_ONLY_RESET : with CDC interface only
+ * - DFU_MAGIC_UF2_RESET         : with CDC and MSC interfaces
+ * - DFU_MAGIC_SKIP              : skip DFU entirely including double reset delay
  *
  * Note: for DFU_MAGIC_OTA_APPJUM Softdevice must not initialized.
  * since it is already in application. In all other case of OTA SD must be initialized
  */
-#define DFU_MAGIC_OTA_APPJUM            BOOTLOADER_DFU_START             // 0xB1
+#define DFU_MAGIC_OTA_APPJUM            BOOTLOADER_DFU_START  // 0xB1
 #define DFU_MAGIC_OTA_RESET             0xA8
 #define DFU_MAGIC_SERIAL_ONLY_RESET     0x4e
 #define DFU_MAGIC_UF2_RESET             0x57
+#define DFU_MAGIC_SKIP                  0x6d
 
 #define DFU_DBL_RESET_MAGIC             0x5A1AD5      // SALADS
 #define DFU_DBL_RESET_APP               0x4ee5677e
@@ -170,13 +172,16 @@ int main(void)
 
   // Serial only mode
   bool serial_only_dfu = (NRF_POWER->GPREGRET == DFU_MAGIC_SERIAL_ONLY_RESET);
+  bool uf2_dfu = (NRF_POWER->GPREGRET == DFU_MAGIC_UF2_RESET);
 
   // start either serial, uf2 or ble
-  bool dfu_start = _ota_dfu || serial_only_dfu || (NRF_POWER->GPREGRET == DFU_MAGIC_UF2_RESET) ||
+  bool dfu_start = _ota_dfu || serial_only_dfu || uf2_dfu ||
                     (((*dbl_reset_mem) == DFU_DBL_RESET_MAGIC) && (NRF_POWER->RESETREAS & POWER_RESETREAS_RESETPIN_Msk));
 
+  bool const dfu_skip = (NRF_POWER->GPREGRET == DFU_MAGIC_SKIP);
+
   // Clear GPREGRET if it is our values
-  if (dfu_start) NRF_POWER->GPREGRET = 0;
+  if (dfu_start || dfu_skip) NRF_POWER->GPREGRET = 0;
 
   // Save bootloader version to pre-defined register, retrieved by application
   // TODO move to CF2
@@ -199,79 +204,85 @@ int main(void)
   }
 
   /*------------- Determine DFU mode (Serial, OTA, FRESET or normal) -------------*/
-  // 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) ) ;
-
-  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;
-
-  // App mode: register 1st reset and DFU startup (nrf52832)
-  if ( ! (just_start_app || dfu_start || !valid_app) )
+  if ( !dfu_skip )
   {
-    // Register our first reset for double reset detection
-    (*dbl_reset_mem) = DFU_DBL_RESET_MAGIC;
+    // DFU button pressed
+    dfu_start  = dfu_start || (button_pressed(BUTTON_DFU) && !dfu_skip);
+
+    // DFU + FRESET are pressed --> OTA
+    _ota_dfu = _ota_dfu  || ( button_pressed(BUTTON_DFU) && button_pressed(BUTTON_FRESET) ) ;
+
+    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;
+
+    // App mode: register 1st reset and DFU startup (nrf52832)
+    if ( ! (just_start_app || dfu_start || !valid_app) )
+    {
+      // Register our first reset for double reset detection
+      (*dbl_reset_mem) = DFU_DBL_RESET_MAGIC;
 
 #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: Supposedly during this time if RST is press, it will count as double reset.
-     * However Double Reset WONT work with nrf52832 since its SRAM got cleared anyway.
-     */
-    bootloader_dfu_start(false, DFU_SERIAL_STARTUP_INTERVAL, false);
+      /* Even DFU is not active, we still force an 1000 ms dfu serial mode when startup
+       * to support auto programming from Arduino IDE
+       *
+       * Note: Supposedly during this time if RST is press, it will count as double reset.
+       * However Double Reset WONT work with nrf52832 since its SRAM got cleared anyway.
+       */
+      bootloader_dfu_start(false, DFU_SERIAL_STARTUP_INTERVAL, false);
 #else
-    // if RST is pressed during this delay --> if will enter dfu
-    NRFX_DELAY_MS(DFU_DBL_RESET_DELAY);
+      // if RST is pressed during this delay --> if will enter dfu
+      NRFX_DELAY_MS(DFU_DBL_RESET_DELAY);
 #endif
-  }
-
-  if (APP_ASKS_FOR_SINGLE_TAP_RESET())
-    (*dbl_reset_mem) = DFU_DBL_RESET_APP;
-  else
-    (*dbl_reset_mem) = 0;
-
-  if ( dfu_start || !valid_app )
-  {
-    if ( _ota_dfu )
-    {
-      led_state(STATE_BLE_DISCONNECTED);
-      softdev_init(!sd_inited);
-      sd_inited = true;
-    }
-    else
-    {
-      led_state(STATE_USB_UNMOUNTED);
-      usb_init(serial_only_dfu);
     }
 
-    // Initiate an update of the firmware.
     if (APP_ASKS_FOR_SINGLE_TAP_RESET())
     {
-      // If USB is not enumerated in 3s (eg. because we're running on battery), we restart into app.
-      APP_ERROR_CHECK( bootloader_dfu_start(_ota_dfu, 3000, true) );
+      (*dbl_reset_mem) = DFU_DBL_RESET_APP;
     }
     else
     {
-      // No timeout if bootloader requires user action (double-reset).
-      APP_ERROR_CHECK( bootloader_dfu_start(_ota_dfu, 0, false) );
+      (*dbl_reset_mem) = 0;
     }
 
-    if ( _ota_dfu )
+    if ( dfu_start || !valid_app )
     {
-      sd_softdevice_disable();
-    }else
-    {
-      usb_teardown();
+      if ( _ota_dfu )
+      {
+        led_state(STATE_BLE_DISCONNECTED);
+        softdev_init(!sd_inited);
+        sd_inited = true;
+      }
+      else
+      {
+        led_state(STATE_USB_UNMOUNTED);
+        usb_init(serial_only_dfu);
+      }
+
+      // Initiate an update of the firmware.
+      if (APP_ASKS_FOR_SINGLE_TAP_RESET() || uf2_dfu || serial_only_dfu)
+      {
+        // If USB is not enumerated in 3s (eg. because we're running on battery), we restart into app.
+        APP_ERROR_CHECK( bootloader_dfu_start(_ota_dfu, 3000, true) );
+      }
+      else
+      {
+        // No timeout if bootloader requires user action (double-reset).
+        APP_ERROR_CHECK( bootloader_dfu_start(_ota_dfu, 0, false) );
+      }
+
+      if ( _ota_dfu )
+      {
+        sd_softdevice_disable();
+      }else
+      {
+        usb_teardown();
+      }
     }
   }
 
-  // Reset Board
+  // Reset peripherals
   board_teardown();
 
   /* Jump to application if valid