HT49CVX Remote Control Receiver SWIP Design Note A/N: HA0077E

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HT49CVX Remote Control Receiver SWIP Design Note A/N: HA0077E

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HT49CVX Remote Control Receiver SWIP Design Note
HT49CVX Remote Control Receiver SWIP Design Note
A/N: HA0077E
This SWIP used decode format (see Fig. infra-red remote control signals. TIMER HT49CVX series devices especially suitable such applications.
Functional Description
This application uses infra-red coding, format which shown following drawing:
Fig.1 coding format use, infra-red signal must connected PC.7/RMT. TIMER used measure pulse width between high going edges. After measuring
HT49CVX Remote Control Receiver SWIP Design Note
high pulse widths, relationship between high sizes used determine received pulse When looking Lead Code Repeat Code, high levels pulse widths measured compared with already defined range determine their function. example, system frequency 4MHz, lo_count>hi_count lo_l<lo_count<lo_h hi_l<hi_count<hi_h, then then received Lead Code Repeat Code. (Note: actual application, under normal conditions, actual waveform received will like that shown Fig.1 with high/low levels reversed). lo_count pulse width hi_count high pulse width, shown Fig. defined lo_l, lo_h defined hi_l, hi_h. user must note that, their system system frequency 4MHz, then four related parameters, lo_l, lo_h, hi_l, hi_h, receiver_define.asm file, must modified, otherwise program will abnormally.
Fig. After receiving first high level level input signal must immediately determined signal Lead Code not. Lead Code, then will automatically initialise. then will continue accept following data signal. After Custom Code Data Code been received, then must determined received Custom Code same predicted value. Data Code will also sent again complemented form. same then SWIP will automatically initialise, received data correct, then flag will set, program will continue determine Repeat Code been received, then corresponding flag. After infra-red signal ended, continuous high level will cause Timer overflow generate interrupt. After overflows interrupts, program will determine that signal terminated will initiate initialization.
HT49CVX Remote Control Receiver SWIP Design Note
Instructions use:
Software RECEIVER_SWIP Subroutine
Name (Label) System Resouces Function HT49CVX BYTES: ACCBAK, STATUSBAK, HI_COUNT, LO_COUNT, BITCOUNTER, rmtv_cnt, RECEIVER_CODE0~RECEIVER_CODE BITS: receiver_en, first_falling, repeat_1st_falling, STATUS_FG, repeat_fg, ok_fg, ok_bit Stack level used lines PC7: Input pins (I/O), non-pull high 4MHz Crystal Multi-function interrupt (Note User should define that used RECEIVER_SWIP receiver_define.asm (Note Call receiver_init Enable receiver swip setting receiver_en disable receiver swip clearing receiver_en user main program. Reciever swip uses RMT, therefore users should pin. User interface When receiver swip enabled, when valid remote control signal sourced pin, ok_bit ok_fg flags will there repeat code signal, repeat_fg flag will until signal disappears. Ok_bit will cleared when signal disappears, ok_fg flag shoud cleared user else will always remote control information will stored receiver_code0~receiver_code3. Subroutine/Macro Subroutine lines fSYS Other resources Function Descriptions Receive format code
HT49CVX Remote Control Receiver SWIP Design Note
Note: Because this application uses Remote control timer overflow interrupt Multi-function interrupt, Remote control timer rising edge interrupt Remote control timer falling edge interupt, user must these interrupts. receiver_define.asm file, user must first select that used. user control this application supplies bits bytes follows:
Receiver_en: receiver_swip user bit: activate, clear stop Ok_fg: when correct infra-red signal been received must
cleared user, otherwise will remain level Repeat_fg: when repeat code received will after signal ended will automatically cleared Receiver_code0~receiver_code3: received signal data, including 2-bit custom code 2-bit data code. Includes receiver_code0~receiver_code1 data code, receiver_code2~ receiver_code3 custom code.
user application main program, user needs declare used external variables declare receiver_exit public variable, shown below: extern receiver_init:near, receiver_swip:near, statusbak:byte, accbak:byte extern fg:bit, receiver_code:byte, receiver_en:bit, repeat_fg:bit public receiver_exit user must, initialization section their Multi-function interrupt service routine, insert following ensure that program runs correctly: MultiFunc accbak,a a,status statusbak,a receiver_en determine swip activated receiver_swip activated then enter swip RECEIVER_EXIT rmt1f rmt0f rmtvf exitint exitint a,statusbak status,a a,accbak reti
HT49CVX Remote Control Receiver SWIP Design Note
Flowchart
Enter SWIP overflow interupt?
Rmtv_cnt decrease result=0?
rising interupt
Move rmt0 lo_count Return Return Move rmt01 hi_count ok_bit
Repeat_1st_falling=1?
Bitcounter= codelength?
First_falling=0?
Clear Repeat_ 1st_falling
Move rmt1 hi_count
Return Clear first_falling Move codelength bitcounter Return
Hi_count> lo_count?
(Hi_countlo_count)<2?
hi_count lo_count range duration
Store
Store
Ok_bit=0? Bitcounter decrease
bitcounter decrease result=0?
repeat_fg repeat_1st_fallin Move rmtv_cnt_init rmtv_cnt
received custom data codes valid?
Return
first_falling repeat_1st_falling Clear ok_bit repeat_fg Move rmtv_cnt_init rmtv_cnt
ok_bit ok_fg
Return
Return
Return
Fig. Receiver SWIP flowchart Note Fig. only gives flowchart part does contain main program.
Source Code
Consult file details. This file contains SWIP application main program (MAIN.ASM). user consult this application example SWIP. definitions SWIP placed file known receiver_define.asm.

HT49CVX Remote Control Receiver SWIP Design Note A/N: HA0077E

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