Mini_COFDM Ethernet module communication control protocol Vcan1886

Mini_COFDM Ethernet module communication control protocol Vcan1886

1. Module Configuration Parameters

The module configuration parameters are written by writing a 256×8 of RAM To achieve this, 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 {AAAAA}

RAM Parameter Description 

RAM[0]: System reset control, readable and writable, Reading and writing represent different meanings:


00 => Reset the whole system, Serial returns {AAAAA}, indicating that the system has been reset

01 => Save the parameters set by the user, Serial returns {000101}, indicates successful execution

02 => Restore parameters to system default parameters, Serial returns {000202}, indicating successful execution

03=> Search for the frequency point of the specified bandwidth. The serial port returns {000303}, indicates successful execution

04=> Search for the specified frequency when the parameters are known, return {000404}, indicates successful execution

05=> reloadkey, Serial port parameter setting of transmitting parameters and data serial port, returns {000505}, indicates successful execution

06=> Dynamically modify the decay parameters of the emission (write RAM[8] The attenuation value takes effect immediately after the command is issued, and does not reset the emission. After power off, and power on again, RAM[8]is the previously saved value),

return{000606},Indicates successful execution

other=> reserve 


Bit[0] => 

‘1’ = Transmitter RF frequency lock

‘0’= Transmitter RF Frequency not locked

Bit[1] => 

‘1’ = Receiver RF frequency lock

‘0’= Receiver over RF Frequency not locked

Bit[7:2] => reserve 

RAM[1]: Function module working state setting, and data serial port rate, readable and writable, Defaults is 0X44

Bit[7:4]: serial speed

“0000” =1200, 










Bit[3] :Parity

‘0’=even effect test, 

‘1’=miraculous effect

Bit[2] :parity switch



Bit[1]: Receiver module working status

‘1’=Receiver module off

‘0’=Receiver module works normally

Bit[0]: Transmitter working status

‘1’=Transmitter module off

‘0’=The transmitter module works normally

RAM[2]: Transmit bandwidth, readable and writable, Defaults 0X14,

Divide the corresponding decimal number by10 The bandwidth set for, ranges from20~80, include20(2M Bandwidth) and 80(8M Bandwidth)

other=> reserve 

RAM[3]~ RAM[4]: Transmitter module RF center frequency, readable and writable Defaults RAM[3] = 0X0D, RAM[4] = 0X48

In units of 100KHz. The maximum value is 25000 and the minimum value is 500.

RAM[5]: Transmitter module FEC Code rate, readable and writable, Defaults 0X00

00 => 1/2

01 => 2/3

02 => 3/4 

03 => 5/6 

04 => 7/8 

other=> reserve 

RAM[6]: Transmitter module modulation mode, readable and writable, Defaults 0X00

00 => QPSK(4QAM) 

01 => 16QAM 

02 => 64QAM

other=> reserve 

RAM[7]: Transmitter module guard interval, readable and writable, Defaults 0X00

00 => 1/32

01 => 1/16 

02 => 1/8 

03 => 1/4 

other=> reserve 

RAM[8]: Transmitter module RF Output power attenuation value, readable and writable, The default value is0X00

00: 0 dB 

01: 1 dB 

02: 2 dB; 


0F:15 db 

other=> reserve 

RAM[9]: Receive frequency bandwidth, readable and writable, Defaults 0X14

Divide the corresponding decimal number by10 The bandwidth set for, ranges from20~80,include20(2M Bandwidth) and80(8M Bandwidth)

other=> reserve 

RAM[10]~ RAM[11]: receiver module RF center frequency, range 158M to 860M, Readable and writable Defaults RAM[10] = 0X0D, RAM[11] = 0X48

In units of 100KHz. The maximum value is 90000 and the minimum value is 2000

RAM[12]~RAM[21]: Receive searched channel parameters, read-only,

struct dibDVBTChannel { 

int8_t spectrum_inversion; 

int8_t nfft; 

int8_t guard; 

int8_t constellation; 

int8_t hrch; 

int8_t alpha; 

int8_t code_rate_hp; 

int8_t code_rate_lp; 

int8_t select_hp; 

int8_t intlv_native; 

} dvbt;

RAM[22]~RAM[37]: The encryption key, the readable and writable, Default value is all zeros

RAM[22] :128 bit encryption key[127-120]bit

RAM[23] :128 bit encryption key[119-112]bit

RAM[24] :128 bit encryption key[111-104]bit

RAM[25] :128 bit encryption key[103-96]bit

RAM[26] :128 bit encryption key[95-88]bit

RAM[27] :128 bit encryption key[87- 80]bit

RAM[28] :128 bit encryption key[79-72]bit

RAM[29] :128 bit encryption key[71-64]bit

RAM[30] :128 bit encryption key[63-56]bit

RAM[31] :128 bit encryption key[55-48]bit

RAM[32] :128 bit encryption key[47-40]bit

RAM[33] :128 bit encryption key[39-32]bit

RAM[34] :128 bit encryption key[31-24]bit

RAM[35] :128 bit encryption key[23-16]bit

RAM[36] :128 bit encryption key[15-8]bit

RAM[37] :128 bit encryption key[7-0]bit

illustrate[127-0]all for0,no encryption

RAM[40]~RAM[43]: For calculating the signal-to-noise ratio, see related documents for details

RAM[44]~RAM[45]: calculate RF power,rf_power Refer to the code for details

RAM[46]~RAM[48]: calculate RF power,n_agc_power Specific reference code

Others RAM Reserved, cannot read or write its contents

2. Module configuration command

The configuration command is realized by sending commands to it through the serial port Command format: {+opcode+RAM address+<operand>+check code+} symbol{}inside is ASCII expressed in code16 base number

{: Indicates the start of the command

+: Indicates that only the connection indicated here, for illustration, does not exist in the actual command

<>: Indicates that there is no

}: Indicates the end of the command

opcode: 00 means to write, FF means to read,1 byte RAM address: 1 byte

operand: the operand of the command1 byte, in read operation, This byte does not

check code: (opcode+ deposit address+ <operand>) mod 256

command return format: 

Operation successful return format: {+register address+register value+check code+} 

reset command did not return

Operation failure return format{FFFFFF}

3. channel size parameter calculation method reference

The maximum channel capacity of the system can be calculated using the following formula: 

Rmax=6.75 x b x FEC x (188/204) x (1/(1+GD)) x (BW/8) 

Rmax: The maximum capacity of the channel(Mb/s)

b: Coupling wave ratio function,QPSK hour b=2, 16QAM hour b=4,64QAMhourb=6 FEC: internal error correction code rate(1/2, 2/3, 3/4, 5/6, 7/8)

GD: guard interval1/4, 1/8, 1/16, 1/32 

BW: Bandwidth toM as a unit

According to the above formula, the maximum capacity of the channel can be calculated under a few parameters. As shown in the table below, yes8mInformation capacity under bandwidth. The system will automatically calculate the size of the coded output stream according to the set channel parameters so that the size of the output stream is not greater than the maximum capacity of the channel.

Mini_COFDM Ethernet module communication control protocol Vcan1886 1

4. Note

on the board L19 location (at U9 On the side, the position is empty when leaving the factory) can add a 0603 The inductance to increase the output power, the increased inductance value can refer to the following figure

Mini_COFDM Ethernet module communication control protocol Vcan1886 2

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