HCS410 Datasheet, PDF (15/36 Pages) Microchip Technology – KEELOQ CODE HOPPING ENCODER AND TRANSPONDER

FIGURE 2-17: DECODER IFF COMMANDS AND WAVEFORMS
Read
Ack pulses
01
Write/Program
TE
Start
2 TE
Response
TRT
16 bits
TBITC
HCS410
TWR
Ack pulses
Challenge
Ack pulses
Encoder Select
Ack pulses
Opcode
TOTD
Transport
Code
32 bits
TTTD
Only when writing Serial
Number, Config or IFF
programming
Data
16 bits
Writing
Repeat 18 times for programming
Opcode
TOTD
Challenge
16/32 bits
Serial number
1 to 32 bits
Response
16/32 bits
Encoder
Select
Ack
TABLE 2-3: IFF TIMING PARAMETERS
Parameter
Symbol
Time Element
IFFB = 0
IFFB = 1
PPM Command Bit Time
Data = 1
Data = 0
PPM Response Bit Time
Data = 1
Data = 0
PPM Command Minimum High Time
Response Time (Minimum for Read)
Opcode to Data Input Time
Transport Code to Data Input Time
IFF EEPROM Write Time (16 bits)
TE
TBITC
TBITR
TPMH
TRT
TOTD
TTTD
TWR
Minimum
—
—
3.5
5.5
—
—
1.5
6.5
1.8
6.8
—
Typical
200
100
4
6
2
3
—
—
—
—
—
Maximum
—
—
—
—
—
—
—
—
—
—
30
Units
µs
TE
TE
TE
ms
ms
ms
ms
© 1997 Microchip Technology Inc.
Preliminary
DS40158C-page 15