If the firmware should already contain predefined settings this guide will help you to compile these into a single binary file.
## Generate default settings
First install on the requested platform the standard firmware and configure everything to your needs. Once you did all changes store them and export them to a `json` file.
## Further prepare default settings
First create a directory `data` inside the following project path: `src/`.
As the export removes all your password you need to add them again to the `json` file. Open the `json` file with a text editor and search for all the `"pwd": ""`. Between the second bunch of quotation marks you have to place the password.
*Note: It's recommended to keep all information in one line to save space on the ESP littlefs partition*
Next rename your export file to `settings.json` and move it to the new created directory. It should be look similar to this:
```
ahoy
|-- src
|-- data
|-- settings.json
|-- config
|-- network
...
```
## modify platform.ini to build factory binary
Open the file `src/platformio.ini` and uncomment the following line `#post:../scripts/add_littlefs_binary.py` (remove the `#`)
## build firmware
Choose your prefered environment and build firmware as usual. Once the process is finished you should find along with the standard `firmware.bin` an additional file called `firmware.factory.bin`. Both files are located here: `src/.pio/build/[ENVIRONMENT]/`
For a 4MB flash size the upload should be finished within 22 seconds.
## Testing
Reboot your ESP an check if all your settings are present.
## Keep updated with 'Mainline'
From time to time a new version of AhoyDTU will be published. To get this changes into your alread prepared factory binary generation environment you have to do only a few steps:
1. revert the changes of `platformio.ini` by executing from repository root: `git checkout src/platformio.ini`
2. pull new changes from remote: `git pull`
3. modify the `platformio.ini` again as you can read above (remove comment)