ELRS Gemini tuner

For a detailed introduction, you can check out my B-site video [ELRS Gemini tuner, I will teach you how to make it for free! 】 https://www.bilibili.com/video/BV1Ys4y1w7Wf
 
1. Product introduction:
    Gemini ELRS 2.4G TX (dual radio frequency 2.4G ELRS high frequency head)
2. Application scenarios:
    can be used for flying machines, fixed wings, model aircraft, etc. High refresh rate, high-quality control links, and long-distance scenarios provide what may be the best solution at present
. 3. Product Overview:
    ELRS is no longer an unfamiliar term in the field of aircraft models such as traversing aircraft. High refresh rate, high-quality, long-distance Distance, open source, and everyone can make it themselves, these are the advantages of ELRS. The current 2.4G ELRS control link uses an sx1280 LoRa radio frequency chip to send and receive data. This project uses two sx1280 radio frequency chips to achieve higher quality control based on the premise of drawing on many open source ELRS projects and ELRS official guidelines. Link and signal quality (LQ) are significantly improved compared to a single radio frequency chip. The word Gemini means "gemini", which is also derived from this.
    The GEMINI TX module has 2 SX1280 transceivers and transmits data packets with a frequency difference of 40MHz simultaneously. True diversity RX is used to receive two packets simultaneously. Transmitting on 2 separate frequencies, this case can be better avoided. DVDA provides better immunity to interference and higher link quality by sending repeated packets one after another on different frequencies.
4. Product parameters:  
    1. Interface: JR warehouse
    2. Main control: ESP32-PICO-D4
    3. RF chip: 2 E28-2G4M27SX
    4. Backpack function: ESP-01F
    5. Maximum power: 250mw (E28 module can be turned on to 500mw, but not recommended, the heat will be very large)
    6. Fan: The latest version already supports fans, please see the PCB file for details
    7. PCB information:
        (1) Board size: 39.888mm x 55.949mm
        (2) Layer : 2 layers (it is recommended to change to a 4-layer board to facilitate impedance matching of WiFi antennas)
        (3) Layout: single-sided layout (convenient for heating table welding)
 
5. Instructions for use:
    Since there is currently no screen, all parameter adjustments rely on LUA scripts. Therefore, only open source remote controls are supported, such as EdgeTX, OpenTX, etc. Please refer to the attachment for specific firmware flashing process and usage instructions.
6. Remarks:
    (1) The total price is about 150-180 yuan
    (2) It is best to buy E28-2G4M27SX directly for the E28 RF chip. If you buy E28-2G4M27S, you need to cut off the PCB antenna and remove the resistor. Shift, please ask customer service for details
 
about the specific firmware flashing process. For other files such as shell files, please see the attachment.