I want to DIY a remote controller that can use ELRS.

English:
ELRS only has open-source modules for receiving and transmitting, but not open-source remote controllers, right?
I want to make my own remote controller that can use ELRS modules. Could you recommend some materials or open-source addresses to me? Thank you.
The remote controller communicates with ELRS modules through a serial port. Is it the CSRF protocol?
Why can off-the-shelf commercial remote controllers use your ELRS modules? Do we need to flash your firmware on those remote controllers?
So, have you written three pieces of firmware?
Are they for the receiving module, the transmitting module, and the transmitting remote controller?
If you can write the firmware for the transmitting remote controller, then do you have the schematics for those remote controllers?
I want to DIY a remote controller. please help me.
Thank you.

Chinese中文：
ELRS只有接收和发射的开源模块，没有开源遥控器，对吗？
我想自己制作一个能用elrs模块的遥控器，请推荐我一些资料，或者开源地址，谢谢。
遥控器与ELRS的模块是串口，用的什么协议通信?CSRF吗？
为什么现成的商品遥控器可以使用你们的ELRS模块，需要给那些遥控器刷你们的固件吗？
所以，你们写了3个固件吗？
分别是接收模块，发射模块，发射遥控器的程序？
如果你们能写发射遥控器的程序，那么你们是不是有那些遥控器的原理图？
我想DIY遥控器，谢谢。