HCS320 Datasheet, PDF (22/32 Pages) Microchip Technology – KEELOQ Code Hopping Encoder

HCS320
FIGURE 8-5:
CODE WORD FORMAT: PREAMBLE/HEADER PORTION
P1
P12
Bit 0 Bit 1
23 TE 50% Duty Cycle Preamble
10 TE Header
Data Bits
FIGURE 8-6:
CODE WORD FORMAT: DATA PORTION
Serial Number
Button Code
Status
LSB
MSB LSB
MSB S3 S0 S1 S2 VLOW RPT
Bit 0 Bit 1 Bit 30 Bit 31 Bit 32 Bit 33 Bit 58 Bit 59 Bit 60 _{Bit 61} Bit 62 Bit 63 Bit 64 Bit 65
Header Encrypted Portion
Fixed Portion
Guard
Time
TABLE 8-3: CODE WORD TRANSMISSION TIMING REQUIREMENTS
VDD = +3.5 to 13.0
Commercial(C):Tamb = 0°C to +70°C
Industrial(I):Tamb = -40°C to +85°C
Code Words Transmitted
All
1 out of 2
1 out of 4
Symbol
Characteristic
Number
of TE
Min.
Typ.
Max.
Min.
Typ. Max. Min. Typ. Max. Units
TE Basic pulse element
1
280 400 620 140 200 310 70 100 155 µs
TBP PWM bit pulse width
3
840 1200 1860 420 600 930 210 300 465 µs
TP
Preamble duration
23 6.4 9.2 14.3 3.2 4.6 7.1 1.6 2.3 3.6 ms
TH
Header duration
10 2.8 4.0 6.2 1.4 2.0 3.1 0.7 1.0 1.6 ms
THOP Hopping code duration 96
TFIX Fixed code duration 102
TG
Guard Time
199
26.9 38.4 59.5 13.4 19.2 29.8 6.7 9.6 14.9 ms
28.6 40.8 63.2 14.3 20.4 31.6 7.1 10.2 15.8 ms
55.6 79.6 123.5 28.1 39.8 61.7 13.8 19.9 30.6 ms
—
Total Transmit Time 430 120.3 172.0 266.7 60.4 86.0 133.3 29.9 43.0 66.5 ms
—
PWM data rate
— 1190 833 538 2381 1667 1075 4762 3333 2151 bps
Note: The timing parameters are not tested but derived from the oscillator clock.
DS41097C-page 22
© 2001 Microchip Technology Inc.