How to configure the parameters of the FPV VTX module

FPV VTX Module Description

  • Small size. 50MM long, 35MM wide, 8MM high
  • Low latency.
  • H265 encoding.
  • The RF index is good. Low stray, high strap
  • Good bandwidth compatibility. Bandwidth is adjustable from 2M to 8M on the same board, in steps of 100KHz
  • Wide voltage power supply. Power supply voltage range: 7V~18V, small current 200mA (12V).
  • RF output with software start function

FPV VTX Module Parameters

  1. Adjustable parameters
    • IFFT：2k
    • Guard interval: 1/4, 1/8, 1/16, 1/32
    • FEC：1/2、2/3、3/4、5/6、7/8
    • Modulation mapping: QPSK (4QAM), 16QAM, 64QAM
    • Bandwidth: 2M~8M bandwidth adjustable, step 100KHz
  2. 128-bit encryption
    • The module supports 128-bit AES encryption
  3. One-way transparent serial port
    • The module supports a one-way transparent serial port transmission.
    • 8 data bits
    • 1 stop bit
    • Support odd parity, even parity, no parity
    • Baud rate: 1200, 2400, 4800, 9600, 19200, 38400 57600、115200、230400
  4. Communication control serial port parameters
    • 8 data bits
    • 1 stop bit
    • even parity
    • Baud rate: 19200
  5. Video format model.
    • CVBS input mode: NTSC, PAL, input mode adaptive.
  6. RF frequency
    • The RF frequency is adjustable from 70MHz to 6GHz in steps of 100KHz.
    • RF maximum output power (below 860M) -15+3 dBm, with shoulder >= 50 dB.
  7. RF output power is controllable
    • RF output power attenuation is adjustable from 0dB~63dB

FPV VTX Module interface, size, and signal definition

Module interface, power supply, control serial port (CTR), and data interface (DATA)

configure the parameters of the FPV VTX module
configure the parameters of the FPV VTX module

FPV VTX Module configuration parameters

RAM parameter description

The module configuration parameters are all implemented by writing to a 256×8 RAM inside the module. The configured parameters are valid after saving reset or powering on again. After the system is powered on or reset, the serial port will print {AAAAAA}

RAM parameter details

RAM[0]: System reset control, readable and writable, reading and writing have different meanings

Write:

  • 00 => Reset the entire system, the serial port returns {AAAAAA}, indicating that the system has been reset.
  • 01 => Save the parameters set by the user. The serial port returns {000101}, indicating successful execution.
  • 02 => The recovery parameters are system default parameters, and the serial port returns {000202}, indicating successful execution.
  • 03=> Stop RF output, and the serial port returns {000303}, indicating successful execution.
  • 04=> Turn on RF output, and the serial port returns {000404}, indicating successful execution.
  • 05=> Turn off the DA output, and the serial port returns {000505}, indicating successful execution. To restore the DA output, just reset the board.
  • Others => Reserved

Read:

  • Bit[0] =>
    • ‘1’ => RF frequency lock
    • ‘0’=>RF frequency is not locked
  • Bit[1] =>
    • ‘1’ => CVBS input lock
    • ‘0’ => CVBS input is not locked
  • Bit[7:2] => reserved

RAM[1]: Data serial port parameter settings, readable and writable, default value 0x44

  • Bit[7:4]: Serial port rate
    • “0000” =1200,
    • “0001”=2400,
    • “0010”=4800,
    • “0011”=9600,
    • “0100”=19200,
    • “0101”=38400,
    • “0110”=57600,
    • “0111”=115200
    • “1000”=230400,
    • “1001”~”1111″=reserved
  • Bit[3]: Parity parity
    • ‘0’=even effect,
    • ‘1’=miraculous effect
  • Bit[2]: Parity switch
    • ‘1’=on
    • ‘0’=off
  • Bit[1:0]: reserved

RAM[2]: Bandwidth, readable and writable, default value 0x50

  • The corresponding decimal number divided by 10 is the set bandwidth, ranging from 20 to 80, including 20 (2M bandwidth) and 80 (8M bandwidth)
  • Others => Reserved

RAM[3]: FEC code rate, readable and writable, default value 0x00

  • 00 => 1/2
  • 01 => 2/3
  • 02 => 3/4
  • 03 => 5/6
  • 04 => 7/8
  • Others => Reserved

RAM[4]: Modulation mode, readable and writable, default value 0x00

  • 00 => QPSK(4QAM)
  • 01 => 16QAM
  • 02 => 64QAM
  • Others => Reserved

RAM[5]: Guard interval, readable and writable, default value 0X00

  • 00 => 1/32
  • 01 => 1/16
  • 02 => 1/8
  • 03 => 1/4
  • Others => Reserved

RAM[6]: reserved

RAM[7]~RAM[22]: encryption key, readable and writable, default value is all zeros

RAM[7]: Bits [127 to 120] of the 128-bit encryption key

RAM[8]: Bits [1119 to 112] of the 128-bit encryption key

RAM[9]: Bits [111 to 104] of the 128-bit encryption key

RAM[10]: Bits [103 to 96] of the 128-bit encryption key

RAM[11]: Bits [95 to 88] of the 128-bit encryption key

RAM[12]: Bits [87 to 80] of the 128-bit encryption key

RAM[13]: Bits [79 to 72] of the 128-bit encryption key

RAM[14]: Bits [71 to 64] of the 128-bit encryption key

RAM[15]: Bits [63 to 56] of the 128-bit encryption key

RAM[16]: Bits [55 to 48] of the 128-bit encryption key

RAM[17]: Bits [47 to 40] of the 128-bit encryption key

RAM[18]: Bits [39 to 32] of the 128-bit encryption key

RAM[19]: Bits [31 to 24] of the 128-bit encryption key

RAM[20]: Bits [23 to 16] of the 128-bit encryption key

RAM[21]: Bits [15 to 8] of the 128-bit encryption key

RAM[22]: Bits [7 to 0] of the 128-bit encryption key

Description [127 to 0] are all 0, no encryption is used

RAM[23]: RF output power attenuation register, readable and writable, The default value is 0x00, range 0~63(dB)

  • 0x00: 0db
  • 0x01: 1 db
  • 0x02: 2 db;
  • ………..
  • 0x0F:15 db
  • Others => Reserved

RAM[24]~ RAM[25]: RF center frequency, in 100KHz. The maximum value is 60000, the minimum value is 700, RAM[24] high byte, Readable and writable. The default frequency is 340MHz,

RAM[26]~ RAM[27]: H265 encoding codeStream size in bits, read-only. (It is automatically calculated by the software inside the module. Please refer to this document for the calculation method)

RAM[28]: reserved

RAM[29]: CVBS video mode, read-only

  • 0X00: No video input
  • 0X01: PAL
  • 0X02:NTSC

RAM[30]: running mode, default 0x00

  • 0X00:VIDEO
  • 0X01: VIDEO+MP2
  • Others: reserved

Other RAM is reserved and its contents cannot be read or written.

FPV VTX Module configuration commands

Configuration commands are implemented by sending commands to it through the serial port.

Command format: {+opcode+RAM address+<operand>+check code+} The symbols {} are all hexadecimal numbers represented by ASCII codes.

           { : indicates the start of the command

           +: Indicates that this only represents the connection, which is used for illustration and does not exist in the actual command.

           <>: Indicates that the parameter is not included in the read command.

           } : indicates the end of the command

           Opcode: 00 means write, FF means read, 1 byte

           RAM address: 1 byte

           Operand: The operand of the command is 1 byte. In the read operation, this byte has no

           Check code: (opcode + storage address + <operand>) mod 256

Command return format:

           The return format if the operation is successful: {+register address+register value+check code+}

                            The reset command did not return

           Operation failure return format: {FFFFFF}

The above operation process is suitable for the following products: FVP VTX Module:

[VF-202406]

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