;12C508 ultrasonic range finder program
;InternalOsc, WDTenabLED
Include
Loopequ10h
dlyCTRequ11h
Tone_cntequ12h; reflection period count
Periodequ13h;tmr0 overflow time
Org0
MOVwfOSCCAL
MOVlwb'10001001'
Option; 1: 2WDTON
MOVlwb'00001101'
trisGPIO
MOVwf0
bcfGPIO, 1; output pulse
;============================================
Mainclrwdt
btfssGPIO, 0; wait for the trigger signal
Gotomain
M2clrwdt
btfscGPIO,0
Gotom2
Callburst
bsfGPIO, 1; start output timing pulse
m1btfscGPIO, 2
Gotom1
bcfGPIO, 1; end output timing pulse
Gotomain
;============================================
Burstclrfloop
MOVlw8
MOVwfloop
burst1MOVlwb'00010000'
MOVwfGPIO
MOVlw3
MOVwfdlyctr
Burst2decfszdlyctr,f
Gotoburst2;12uS
MOVlwb'00010100'
MOVwfGPIO
MOVlw2;(2*3inst*1uS)-1uS=5uS
MOVwfdlyctr; 5uS+(8*1uS)=13uS
Burst3decfszdlyctr,f
Gotoburst3
Nop
Decfszloop,f
Gotoburst1
MOVlw0x00
MOVwfGPIO
Retlw0
;=================================
toneclrfTMR0
t1btfscGPIO, 2
Gotot1
MOVfwTMR0
clrfTMR0
MOVwfperiod
MOVlw21;if(period>22&&period<30)
Subwfperiod,w
btfssSTATUS, C
Gotot2
MOVlw30
Subwfperiod,f
btfscSTATUS, C
Gotot2
Decfsztone_cnt,f;25uSperiodOK,so
Gotot1;ifnotyet3ofthem,keeplooking
Retlw0;else-success-return
t2MOVlw3
MOVwftone_cnt
Gotot1
;==============================================
End
However, due to technical and cost reasons, it is not widely used. In recent years, RFID technology has developed by leaps and bounds. With the development of large-scale integrated circuit and network communication technology, RFID technology has entered the commercial application field, and began to develop from the initial low frequency (125kHz) and high frequency (13.56mhz) to uHF (860 ~ 960MHz) and microwave. RFID technology has become one of the most promising information technologies in the new era because of its unique advantages showing great development potential and application space. In both low and high frequency bands, China has independently developed RFID chips in accordance with ISO14443 A, B and ISO15693 standards, which have been successfully applied in major projects such as city bus all-in-one card and second-generation resident ID card. However, in the uHF and microwave field, China started late, technology and products are still relatively short. In this context, this paper studies the design of 915MHz rf card reader. The system can be applied to vehicle monitoring, remote control, telemetry, access control system, identity identification, non-contact radio frequency smart card, wireless 485/232 data communication, safety and fire prevention and other fields.
915MHZ Rubber Antenna,915MHZ Antenna with magnetic base,915MHZ fiberglass antenna
Yetnorson Antenna Co., Ltd. , https://www.yetnorson.com