CN102938197A

CN102938197A - Method for decoding infrared remote control by means of input capture interrupt mode

Info

Publication number: CN102938197A
Application number: CN2012104368672A
Authority: CN
Inventors: 陈洁
Original assignee: HEFEI YIDUAN COMMUNICATION TECHNOLOGY Co Ltd
Current assignee: HEFEI YIDUAN COMMUNICATION TECHNOLOGY Co Ltd
Priority date: 2012-10-26
Filing date: 2012-10-26
Publication date: 2013-02-20

Abstract

The invention discloses a method for decoding infrared remote control by means of an input capture interrupt mode and relates to a method for decoding the infrared remote control. The method comprises the steps of allocating an input capture timer into a singlechip main program, starting the input capture timer and enabling interrupt; obtaining a capture time value through interrupt trigger; comparing the capture time value and the last capture time value and calculating interval between the capture time value and the last capture time value; enabling a state machine to compare whether the pulse width accords with the front end of a guidance code; determining whether the front end of the guidance code is a code head; enabling the state machine to be in a decoding state and compare whether the pulse width accords with coding rules; storing a coding value in a coding variable; storing the captured value in the variable to be used in the next comparison; and clearing a sign bit, and turning over the edge trigging mode to make preparations for the next capture. By means of the method, only one input capture channel of the timer is occupied, and a central processing unit (CPU) can do other work, so that few system resources are occupied, an executive program has high efficiency, the expansibility is good, and influence on other tasks of a system is small.

Description

The method of input capture interrupt mode decoding infrared remote control

Technical field:

The present invention relates to the method for decoding infrared remote control, relate in particular to the input capture mode infrared method of decoding.

Background technology:

So-called infrared remote control system mainly is made of the two large divisions: the infrared coding radiating portion, the infrared decoding receiving unit, the infrared emission part is mainly by keyboard, the infrared coding chip, power supply, infrared transmitting tube forms, the infrared decoding part is by infrared receiving circuit, infrared decoding, power supply and application circuit form, the specialized hardware decoding chip that tradition is used, its function is fixed, the corresponding a kind of special-purpose decoding chip of a kind of coded format, very flexible, and mostly adopt now coded signal is inputted single-chip microcomputer, utilize single-chip microcomputer to decode, decoding software can be according to the actual needs of oneself, design various functions, and can suitably adjust, increase the function of existing circuit, by revising software, can adapt to various remote control coding chip, and software decode adopts query method usually, and namely single-chip microcomputer is constantly inquired about the level variation of infrared port, and it takies a large amount of CPU time and resource, when there is bit error rate height in other task situation in system, its step following (seeing Fig. 1):

Step 100: initialization, GP configuring IO is the infrared encoded signal signal input part;

Step 101: waiting signal is high level, opens the time that timer is measured high level, until run into low level, judges whether to meet the requirement of pulsewidth, does not meet then to abandon and thinks noise signal;

Step 102: measure low level width, do verification;

Step 103: the above-mentioned test that circulates, until all positions are all decoded complete.

Exist following defective in this query method decoding process:

1, the query method principle is the state that the port of CPU is being inquired about port always, is detecting width and the counting of pulse always, comes the ranging pulse width with the method, decodes according to coding rule again.

2, a large amount of cpu resource of query method consumption, or prohibit interruption, if opened interruption, being difficult to obtain correct time, system further expands difficulty.

Summary of the invention:

In order to solve the existing problem of background technology, the invention provides a kind of method of input capture interrupt mode decoding infrared remote control, comprise that step is as follows:

Configuration input capture timer starts the input capture timer in the single-chip microcomputer master routine, opens interruption;

Down trigger is obtained and is caught constantly value;

Value compares with catching last time constantly, calculates two minor ticks, namely is pulsewidth;

Whether state machine comparison pulsewidth meets the preamble code front end;

Be confirmed whether it is harbour;

State machine enters decoded state and compares pulsewidth whether meet coding rule;

Coding variable save encoded radio;

The value of catching deposits variable in, for next time relatively;

Prepare for catching next time along triggering mode in clear flag position, flipping side.

Whether described state machine comparison pulsewidth meets the preamble code front end, is then to be confirmed whether to be harbour, otherwise the clear flag position, flipping side is prepared for catching next time along triggering mode.

Described being confirmed whether is harbour, is then to enter decoded state, compares pulsewidth and whether meets the preamble code front end otherwise return.

Described state machine enters decoded state and compares pulsewidth whether meet coding rule, is then encoded radio to be saved in the coding variable, otherwise namely thinks clutter, abandons.

The every preservation first encoding of described coding variable value, bits of coded counting number value adds 1, until figure place meets the predictive encoding figure place, decoding is finished, state machine jumps to idle condition.

The inventive method, used a timer, this timer has the input capture function, when signal occurs to become along saltus step, can automatically record the moment when edge transition occurs, and triggering is interrupted, only in interrupt handling routine, process double moment value, calculate the signal pulsewidth with this, again decoding, input capture are exactly one or several identical edges of check, repeatedly calculate and average, again according to must computing obtaining the cycle information of inputting waveform, each passage can only be configured at every turn not be that rising edge is exactly negative edge according to difference.

The present invention adopts input capture interrupt mode decoding infrared remote control, only need take the input capture passage of a timer, and CPU can do other work, and occupying system resources is few, and executive routine efficient is high, and favorable expandability is little on the impact of other task of system.

Description of drawings:

Fig. 1 is the process flow diagram of the inventive method.

Embodiment:

With reference to Fig. 1, performing step of the present invention is as follows:

S1: configuration input capture timer in the single-chip microcomputer master routine, start the input capture timer, open interruption;

S2: down trigger is obtained and is caught constantly value.

S3: and caught the moment value last time relatively, calculate two minor ticks, namely be pulsewidth.

S4: state machine is in idle condition, and this moment, relatively whether pulsewidth met the preamble code front end, was then to change S5 over to, withdrawed from otherwise change S8 over to.

S5: be confirmed whether it is harbour, be then to enter decoded state, otherwise change S4 over to.

S6: state machine is in decoded state, this moment, relatively whether pulsewidth met: the coding rule of data " 0 " or data " 1 " or data " F ", be that then encoded radio displacement enters in the coding variable and preserves, bits of coded counting number value adds 1, until figure place meets the predictive encoding figure place, decoding is finished, state machine jumps to idle condition, i.e. S4, otherwise think clutter, abandon, change S7 over to.

S7: the value of catching deposits variable in, for next time relatively.

S8: prepare for catching next time along triggering mode in clear flag position, flipping side.

Claims

1. the method for an input capture interrupt mode decoding infrared remote control comprises that step is as follows:

Down trigger is obtained and is caught constantly value;

Whether state machine comparison pulsewidth meets the preamble code front end;

Be confirmed whether it is harbour;

Coding variable save encoded radio;

The value of catching deposits variable in, for next time relatively;

2. method according to claim 1 is characterized in that, whether described state machine comparison pulsewidth meets the preamble code front end, is then to be confirmed whether to be harbour, otherwise the clear flag position, flipping side is prepared for catching next time along triggering mode.

3. method according to claim 1 is characterized in that, described being confirmed whether is harbour, is then to enter decoded state, compares pulsewidth and whether meets the preamble code front end otherwise return.

4. method according to claim 1 is characterized in that, described state machine enters decoded state and compare pulsewidth whether meet coding rule, is then encoded radio to be saved in the coding variable, otherwise namely thinks clutter, abandons.

5. method according to claim 4 is characterized in that, the every preservation first encoding of described coding variable value, and bits of coded counting number value adds 1, until figure place meets the predictive encoding figure place, decoding is finished, state machine jumps to idle condition.