OpenVTX TX5823 5.8G image transmission

Foreword: Since mid-2022, some big guys have been researching homemade analog image transmission transmitters. We all know the difficulty and complexity of high-frequency circuit design and impedance matching. With the efforts of the big guys, it has finally been pushed to a usable and mature work, making it possible for everyone to DIY a cheap and practical image transmission transmitter. , this project pays tribute to those pioneers who paved the way for us!
 
Reference project: 200MW triangular image transmission https://oshwhub.com/avanx/200MWsan-jiao-tu-zhuan (same solution as EWRF E7082VM).
This project is a DIY hardware implementation of the OpenVTX open source project. Regarding OpenVTX, you can learn more about: https://github.com/OpenVTx/OpenVTxWhat
 
is OpenVTX? OpenVTX is an open source image transmission firmware that supports MSP, TBS SmartAudio, and IRC Tramp parameter adjustment protocols, and can automatically identify these protocols. Especially when using the MSP protocol and BF 4.4 or above firmware, [Lamp] can automatically configure and correct the image transmission frequency table (you do not need to manually fill in the flight control configuration).
The unique racing mode, when enabled, will force it to work in pit mode when powered on, so as not to interfere with other pilots.
Firmware update is simple, you can directly use the online web configurator to flash the firmware through the flight controller.
OpenVTX firmware currently supports flashing some models of products from EWRF, Happymodel, BetaFPV, EACHINE and other manufacturers, as well as DIY image transmission.
 
Supports remote parameter adjustment via the SmartAudio protocol on the flight control side. You can also use buttons (LED status indication) to change the frequency band, channel, and power, with a total of 48 frequency points (the available frequency points depend on the firmware and image transmission table. If you have the ability, you can add additional UOH 24 by yourself. Frequency points) Power level Pitmode (0), 25, 100, 200, 400, 600 (pay attention to heat dissipation conditions for high power!)
 
The meaning of the three LED indicators: red light indicates working status (usually always on, flashing, change and save Configuration, 1 long and short flashes 3 times to report an error), green and blue lights indicate the current channel, frequency, and power. (For example, the green light flashes 1 time, then the blue light flashes 5 times, the green light flashes 2 times, the blue light flashes 4 times, the green light flashes three times, and the blue light flashes 5 times. It means R-band 4 channels, power level 5 )//If the indicator light function is turned off, or working under the Trump protocol, the display rule of the indicator light will be another.
Press and release the button (the time cannot be too short), adjust one frequency in sequence, and cycle according to the image transmission table. For example, the next channel of L8 is A1, and the frequency band cannot be adjusted individually. Press and release the button for more than 1 second to adjust to the next power level.
 
 
However, since the existing solutions are all designed with discrete components, they only provide PCB files and Gerber in AD format. There are also special requirements for PCB boards and many restrictions. The types of IC and RLC materials involved are complex, with more than 50 types, and they are all in small patch packages of QFN, 0402 or even 0201, which requires certain technical and visual requirements. The trouble and cost of material procurement also discourage some DIYers, not to mention that high-frequency circuits have higher quality requirements for resistors, capacitors, crystal oscillators and other components. These factors directly affect the effect of the final product and the success rate of DIY.
In order to promote popularization, reduce the difficulty of DIY, and improve the success rate, I commissioned a master to draw a DIY image transmission based on the TX5823 module. Features:
1. The radio frequency part uses finished modules with shielding covers. The effect and stability are guaranteed, and it is simple and easy to use. 2. 0603 single-sided components can be easily completed using a heating plate or soldering iron. 3. Pickup integrated with MAX9812 AGC op amp. Finally: the TX5823 module is widely found in old FPV image transmission transmitters, such as Chuangxinke’s TX5828 transmitter. You can even move the board directly to give your old 32ch dial-coded frequency-selected image transmission a new life and have modern product images. All functions of the transmission, even exceeding 200mw, unleashing the maximum potential of the 6659e amplifier!
 
The general TX5823 module is already SPI controlled for frequency selection when leaving the factory. There is no need to remove the 1k resistor on pin 1 of RTC6705 and the 10nf capacitor on pin 26.
TX5823 is available in 200mw and 600mw fixed power versions. Later, we may introduce how to modify the ordinary TX5823 module so that its PA output power can be freely adjusted.
 
See attachments for Gerber board-making files, BOM tables, and welding point bitmaps.
For the tutorial on flashing the microcontroller bootloader and firmware, you can also refer to the post in the link at the beginning (note that flashing the firmware requires connecting to the hardware serial port tx of the flight control, and the soft serial port does not work).
 
Hardware details:
2~6s power input, mmcx antenna interface, 30.5*30.5 flying tower mounting hole pitch, 1.25 6Pin terminal or welding connection. Wiring definition:
AUD external audio input RX Parameter adjustment connected to any TXVXX of the flight control Battery power input positive GND Battery power input negative VID Video input 5V GND - the onboard BEC 5V output can power the camera