HCS410_01 Datasheet, PDF (14/36 Pages) Microchip Technology – KEELOQ® Code Hopping Encoder and Transponder

HCS410
FIGURE 2-17: DECODER IFF COMMANDS AND WAVEFORMS
Read
Ack pulses
Preamble
01
Write/Program
Start
2 TE
3TE 3TE
TETE
Response
TRT
16 bits
TBITC
TWR
ACK pulses
Challenge
ACK pulses
Encoder Select
ACK pulses
Opcode
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
Preamble
01
TOTD
Challenge
16/32 bits
Response
TWR
16/32 bits
TWR
Serial number
1 to 32 bits
Encoder
Select
ACK
TABLE 2-3: IFF TIMING PARAMETERS
Parameter
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)
Symbol
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
DS40158E-page 14
Preliminary
 2001 Microchip Technology Inc.