docs: Fix and extend the DFU documentation page
@@ -13,15 +13,20 @@ DFU is supported by ESP32-S2 chips. The necessary connections for the USB periph
+------+-------------+
| GPIO | USB |
+======+=============+
-| 19 | D- (green) |
+| 20 | D- (green) |
+------+-------------+
-| 20 | D+ (white) |
+| 19 | D+ (white) |
+------+-------------+
| GND | GND (black) |
+------+-------------+
-| | +5V (red) |
+| +5V | +5V (red) |
+------+-------------+
+.. note::
+ The ESP32-S2 chip needs to be in bootloader mode for the detection as a DFU device and flashing. This can be
+ achieved by pulling GPIO0 down (e.g. pressing the BOOT button), pulsing RESET down for a moment and releasing
+ GPIO0.
+
The software requirements of DFU are included in :ref:`get-started-get-prerequisites` of the Getting Started Guide.
Section :ref:`api_guide_dfu_build` describes how to build firmware for DFU with ESP-IDF and
@@ -95,5 +100,5 @@ Common errors
An easy way of checking the tool is running ``dfu-util --version``. Please see :ref:`get-started-get-prerequisites` for
installing ``dfu-util``.
- The reason for ``No DFU capable USB device available`` could be that the USB driver wasn't properly installed on
- Windows (see :ref:`api_guide_dfu_flash_win`) or udev rule was not setup on Linux
- (see :ref:`api_guide_dfu_flash_udev`).
+ Windows (see :ref:`api_guide_dfu_flash_win`), udev rule was not setup on Linux
+ (see :ref:`api_guide_dfu_flash_udev`) or the device isn't in bootloader mode.
