add u-boot docs

docs/3.Flashing the Fydetab Duo.md

@@ -24,16 +24,6 @@ Here is a step-by-step guide for flashing a new OS onto your Fydetab Duo.
 - If successful, your flashing device should be able to connect to the Fydetab Duo.The device’s LED will remain off, and the screen will stay completely dark.
 - Occasionally, the screen may display an image indicating that the device is in Loader Mode. Note that this image may not always appear due to display issues.
 
-### 4. Enter Maskrom mode in case of brick
-
-If for some reason an unsupported image has been flashed or something has been corrupted making it impossible to access Loader/Maskrom mode with the button combination explained in step 2, there is the possibility to use the Maskrom button on the Fydetab's PCB. 
-
-![](/img/fydetab_maskrom_button_pcb.jpg)
-
-- Force a shutdown by pressing and holding the power button for 10 seconds.
-- Press and hold MASKROM mode button from the PCB. While holding down the button connect the USB from the tablet to the PC.
-- Open the flashing tool from the next section and you will see that a device is detected in MASKROM mode.
-
 ## Utilising the image flash tool provided by Rockchip
 
 ### Using Linux

docs/Hacking your Fydetab Duo/1.Fydetab Duo Boot Modes & Bootloader Guide.md

@@ -0,0 +1,103 @@
+---
+id: u-boot
+title: Fydetab Duo Boot Modes & Bootloader Guide
+---
+
+## Entering Loader / Recovery Mode
+
+![Loader Mode Image](/img/u-boot/fydetab_recovery.jpeg)
+
+To access the Loader Mode on your Fydetab Duo, follow these steps:
+
+1. **Shut down the Device** 
+    - Ensure your Fydetab Duo is completely powered off.
+
+2. **Connect USB Cable** 
+    - Insert a USB cable into the Fydetab Duo and the host device.
+
+3. **Activate Loader Mode** 
+    - Press and hold both the Volume Up button and the Power button simultaneously.
+
+4. **Confirm Loader Mode** 
+    - The Fydetab Duo will boot into Loader Mode, allowing firmware updates and other maintenance tasks.
+
+## Entering USB Mass Storage(UMS) Mode
+
+![UMS Image](/img/u-boot/fydetab_usb.jpeg)
+
+To put your Fydetab Duo into UMS Mode, proceed with the following:
+
+1. **Shut down the Device** 
+    - Ensure the Fydetab Duo is turned off.
+
+2. **Prepare for UMS Mode** 
+    - Press and hold the Volume Down button and the Power button simultaneously.
+
+3. **Connect USB Cable** 
+    - Plug in a USB cable to the Fydetab Duo and the host device.
+
+4. **Confirm UMS Mode** 
+    - The device will enter UMS Mode, acting as a USB disk that can be accessed by the host computer.
+
+## Low Power Charge Mode
+
+Understanding the low power charging behaviour in U-Boot:
+
+1. **Critical Battery Level `<3%`**
+    - If the battery capacity falls below 3% and the device is not connected to a charger, U-Boot will automatically shut down the system to protect the battery and your data.
+
+2. **Low Battery Level `<8%`**
+    ![Low Battery Image](/img/u-boot/fydetab_batt.jpeg)
+    - If the battery capacity is below 8%, U-Boot will remain on the charging screen until the battery charges to at least 8%, preventing the device from booting until it reaches a safer charge level.
+
+## Compiling and Replacing U-Boot
+
+Follow these instructions to compile U-Boot and replace the original firmware on your Fydetab Duo:
+
+1. **Update Overlay**
+    - Ensure you have the [latest version](https://github.com/openFyde/overlay-fydetab_duo-openfyde/commit/42dd10c82cd0fdbb8880dd1e00cc7dfd7b32f4cd#diff-93ad86d362c5df27f11a47c79972d465f70f322c92b4ae25798364bd1ce8614e) of [overlay-fydetab_duo-openfyde](https://github.com/openFyde/overlay-fydetab_duo-openfyde).
+
+2. **Compile U-Boot**
+    - Enter the `cros_sdk` environment.
+    - Execute the following command:
+      ```
+      emerge-${your_board} virtual/u-boot
+      ```
+
+3. **Locate Compiled Files**
+    - If the compilation is successful, uboot.img and resource.img will be created in `/build/${your_board}/boot`.
+
+4. **Transfer Files to Device**
+    - Copy the uboot.img and resource.img files to your Fydetab Duo.
+
+5. **Flash Images to eMMC**
+    - Use the following commands to flash the images:
+      ```
+      dd if=uboot.img of=/dev/mmcblk0p11 conv=fsync
+      dd if=resource.img of=/dev/mmcblk0p10 conv=fsync
+      ```
+
+## Customising U-Boot Display Images
+
+To personalise the splash images (they are exported as bitmap images in the file system) used in U-Boot, follow these steps:
+
+1. **Replace BMP Files**
+    - In the [overlay-fydetab_duo-openfyde/sys-boot/rk-uboot-resource/files/](https://github.com/openFyde/overlay-fydetab_duo-openfyde/tree/main/sys-boot/rk-uboot-resource/files) directory, replace the existing BMP files with your own (ensure the filenames remain unchanged).
+
+2. **Rebuild U-Boot Resource**
+    - Enter the `cros_sdk` environment.
+    - Run the following command:
+      ```
+      emerge-${your_board} rk-uboot-resource
+      ```
+
+3. **Transfer New Resource Image**
+    - Copy the newly created resource.img from `/build/${your_board}/boot` to your Fydetab Duo.
+
+4. **Flash New Resource Image**
+    - Use the following command to replace the original resource image on partition 10:
+      ```
+      dd if=resource.img of=/dev/mmcblk0p10 conv=fsync
+      ```
+
+The following is our [design file](/img/u-boot/fydetab_batt.psd) for the BMP images. Please note that there is a 90-degree rotation in the design file to fit the screen.

docs/Hacking your Fydetab Duo/_category_.json

@@ -0,0 +1,7 @@
+{
+    "label": "🛠️ Hacking your Fydetab Duo" ,
+    "position": 4,
+    "link": {
+        "type": "generated-index"
+    }
+}