CN102130671A - Special chip for DiSEqC switch - Google Patents

Abstract

The invention relates to a special chip for a DiSEqC switch, comprising a driving module, an OSC (Open Source Commerce) module, an amplifying module, a decoding module and a filter shaping module, which are integrally installed; 22KHz carrier signals are transmitted into the decoding module after being amplified by the amplifying module and shaped by the filter shaping module; after being verified and analyzed, demodulated instructions select output LNB (Low Noise Block) channels; at last, the driving module outputs a valid level to switch on or off the LNB channels; and the OSC module provides a work frequency for the decoding module. In the invention, based on DiSEqC proposal instructions, a CMOS (Complementary Metal Oxide Semiconductor) technology is adopted to produce special integrated circuits to realize DiSEqC switch functions; the quantity of peripheral discrete devices can be greatly reduced, the production can be saved and the system stability can be improved; thus the special chip for a DiSEqC switch is suitable for mass production, thereby overcoming defects in the prior art.

Description

DiSEqC four selects one to switch the switch special chip

Technical field

The present invention be more particularly directed to a kind of diverter switch chip that is applied to satellite receiving system of technical field of integrated circuits.

Background technology

The scheme that DiSEqC four selects a switching switching system to adopt in the present set top box for satellite receiver that exists is based on DiSEqC protocol instructions system employing high frequency amplification+microcontroller+peripheral discrete devices realization, its operation principle is: in the set top box for satellite receiver, by coaxial wire of frequency division multiplexing, DiSEqC four selects one to switch switch receive serial signal (instruction) through the 22KHz carrier modulation from coaxial wire, the decoding corresponding LNB tuner of backgating (satellite receiver generally has 4 LNB tuners) is connected with coaxial wire, goes thereby the satellite programming of needs is sent in the satellite receiver by coaxial cable.Disperse but the peripheral components of above-mentioned diverter switch system, the cost height, stability is poor, is difficult to produce in enormous quantities.

Summary of the invention

The objective of the invention is to propose a kind of DiSEqC four selects one to switch the switch special chip, it is based on the DiSEqC protocol instructions, adopt CMOS technology to make application-specific integrated circuit (ASIC) and realize that DiSEqC four selects one to switch switching function, can reduce the quantity of peripheral discrete devices greatly, save and produce, improve the stability of a system, be fit to volume production in enormous quantities, thereby overcome deficiency of the prior art.

For achieving the above object, the present invention has adopted following technical scheme:

A kind of DiSEqC four selects one to switch the switch special chip, and it is characterized in that: described chip comprises driver module, OSC module, amplification module, decoder module and the filter shape module of integrated setting; The 22KHZ carrier signal is after amplification module amplifies, after the shaping of filter shape module, send into decoder module, output LNB passage is selected in the instruction that demodulates behind check analysis, come gating or cut off the LNB passage by driver module output significant level at last, the OSC module provides operating frequency for decoder module.

Say that further described chip adopts the SOP8 packing forms.

Described LNB passage is more than the two-way, and behind gating one LNB passage, unless this chip receives the instruction of shutdown command or all the other LNB passages of gating, otherwise the LNB passage of current gating is continuously effective, and keeps low level output.

Described significant level adopts low level or high level.

Description of drawings

Fig. 1 is the SOP8 encapsulating structure schematic diagram of a preferred embodiment of the present invention;

Fig. 2 is the realization block diagram of a preferred embodiment of the present invention;

Fig. 3 is the circuit diagram of a preferred embodiment of the present invention.

Embodiment

In order to realize diverter switch system in the set top box for satellite receiver more cheaply, the present invention is based on the DiSEqC protocol instructions, take CMOS technology to make application-specific integrated circuit (ASIC) and realize that DiSEqC four selects one to switch switching function.Consult shown in Figure 1ly, the present invention takes the SOP8 packing forms, and its pin is respectively:

The pin position	Title	Type	Function declaration
					1	VDD	--	Work positive supply/signal input
2	LNB4	O	Four-way output
				3	LNB3	O	Third channel output
4	CAP	I/O	Thebypass AC signal
				5	OSC	--	Frequency of oscillation is regulated, and connects a resistance to VDD
6	LNB1	O	First passage output
				7	LNB2	O	Second channel output
8	VSS	--	The work negative voltage

The present invention proposes following technical scheme: built-in OSC circuit provides clock to system.Built-in small signal amplification circuit and filtering shaping circuit, demodulate instruction by the 22khz carrier modulation, the instruction of decoding circuit after to demodulation carried out check analysis and determined whether within the DiSEqC range of instructions that can respond of the present invention, final definite which passage of gating, by drive circuit output significant level, realize gating LNB function at last.Behind the gating LNB passage, unless receive shutdown command of the present invention, or other one road LNB passage of gating, otherwise the passage of current gating keeps low level output with continuously effective.

When initially powering on, gating LNB1 passage of the present invention is effective.When receiving start-up command of the present invention, the LNB passage when gating shut down last time.When receiving shutdown command, cut off LNB1, LNB2, LNB3 and LNB4.

Consult shown in Figure 2: command signal has DC component, 22KHZ carrier signal, high frequency clutter by the CAP filtering by vdd terminal serial input in the input signal.DC component provides the operating voltage of this chip, the 22KHZ carrier signal is after amplification module amplifies, after the filtering shaping circuit shaping, send into decoder module, the OSC module provides operating frequency for decoder module, the instruction that demodulates comes gating LNB passage by drive circuit output significant level at last through which output channel of check analysis backgating.

The DiSEqC agreement that the present invention can respond is as follows:

One. the switching on and shutting down instruction

Start-up command: E0～E3 10 03; Shutdown command: E0～E3 10 02.Totally 27 of instructions comprise that 3 bytes add 3 odds, and first byte " E0～E3 " is all effective.Receive the then last passage of preserving of gating of start-up command, receive that shutdown command then cuts off all passages immediately,

Two. the channel response instruction

The DiSEqC instruction is 36, and 4 bytes add 4 odds, and form sees the following form.

Start bit

P

Address bit

P

Command bit

P

Data bit

P

Annotate: P is an odd parity bit; All instructions all are high-order preceding, low level after.

DiSEqC signal instruction function sees the following form:

Annotate: the acquiescence that powers on is selected first passage LNB1; Address bit " E0～E3 " is all effective; " X " expression " 0～F " in the data bit, promptly " 0～F " is all effective.

Three .Tone Burst command formats

The 22khz carrier wave that ToneburstA:12.5ms is long.

ToneburstB：

Numerical value FF

P

Further set forth implementation of the present invention below in conjunction with Fig. 3 and reach the response that DiSEqC is instructed: the OUT end links to each other with set-top box by coaxial cable, command signal by the 22khz carrier modulation is imported the present invention by the vdd terminal serial, when supposing this instruction for " E01038F0 " instruction, L1 pin output low level signal of the present invention, coupled PNP triode conducting, make VDD to LNB1 tuner power supply, the vision signal passed back of LNB1 is delivered to set top box for satellite receiver by the OUT end subsequently.Above-mentioned port OUT connects top box of digital machine, and port LNB1～LNB4 connects four tuners.

Above preferred embodiment is only for the usefulness that the present invention is described, but not limitation of the present invention, person skilled in the relevant technique under the situation that does not break away from the spirit and scope of the present invention, has been done various conversion or modification, all belongs to category of the present invention.

Claims (4)

1. a DiSEqC four selects one to switch the switch special chip, and it is characterized in that: described chip comprises driver module, OSC module, amplification module, decoder module and the filter shape module of integrated setting; The 22KHZ carrier signal is after amplification module amplifies, after the shaping of filter shape module, send into decoder module, output LNB passage is selected in the instruction that demodulates behind check analysis, come gating or cut off the LNB passage by driver module output significant level at last, the OSC module provides operating frequency for decoder module.

2. DiSEqC four according to claim 1 selects one to switch the switch special chip, it is characterized in that: described chip adopts the SOP8 packing forms.

3. DiSEqC four according to claim 1 selects one to switch the switch special chip, it is characterized in that: described LNB passage is more than the two-way, behind gating one LNB passage, unless this chip receives the instruction of shutdown command or all the other LNB passages of gating, otherwise the LNB passage of current gating is with continuously effective, and the output of maintenance low level.

4. DiSEqC four according to claim 1 selects one to switch the switch special chip, it is characterized in that: described significant level adopts low level or high level.

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