nm95hs02 National Semiconductor Corporation, nm95hs02 Datasheet - Page 5

• Manufacturer Part Number: nm95hs02
• Description: Hisec-tm High Security Rolling Code Generator
• Manufacturer: National Semiconductor Corporation

Bit Coding Formats
The NM95HS01 02 HiSeC Generator supports eleven-bit
coding formats which may be used for IR and RF transmis-
sion Seven-bit formats are available for RF applications
and four are available for IR applications One-bit format is
reserved for future use
Bit coding formats are selected by configuring four bits in
the EEPROM array IRSEL PRSEL2 PRSEL1 and PRSEL0
Table II shows the possible bit coding options available
Each bit coding format has a distinction which may be ad-
vantageous for a particular application RF bit coding format
0 is the simplest bit coding scheme and data may be easily
recovered from a transmission by exclusive OR-ing the data
and clock stream Both RF bit coding formats 0 and 2 have
a DC level that is independent of the data
RF format 4 and the IR modes operate with a constant
transmission energy per message and RF coding formats
1 3 5 and 7 are pulse-width modulated (PWM) formats
which are relatively easy to decode RF coding format 7 has
a low duty cycle
The IR bit coding formats are modulated versions of RF
coding format 4 and are all suitable for IR applications The
duty cycle and number of pulses are variable among these
four to allow the user to fine tune the IR circuit power curve
Bit Transmission Coding Formats
RF Bit Coding Format 0 (Manchester Code)
RF Bit Coding Format 2 (50% Duty Cycle)
RF Bit Coding Format 4 (IR Style)
TL D 12302 – 10
TL D 12302 – 6
TL D 12302 – 8
5
IR bit coding formats all follow the same general pattern In
this mode a logic ‘‘1’’ is always two periods long and a ‘‘0’’
is always three periods long This may be an important con-
sideration when considering preamble and sync timing
Waveform diagrams for all available RF and IR bit transmis-
sion coding formats are shown below
IRSEL PRSEL2 PRSEL1 PRSEL0
0
0
0
0
0
0
0
0
1
1
1
1
1
RF Bit Coding Format 3 (25% 50%
RF Bit Coding Format 5 (33% 66%
RF Bit Coding Format 1 (33% 66%
TABLE II Transmission Bit Coding Options
0
0
0
0
1
1
1
1
0
0
0
0
1
X
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
X
RF Bit Coding Format 0
RF Bit Coding Format 1
RF Bit Coding Format 2
RF Bit Coding Format 3
RF Bit Coding Format 4
RF Bit Coding Format 5
RF Bit Coding Format 7
IR Bit Coding Format 1
IR Bit Coding Format 2
IR Bit Coding Format 3
IR Bit Coding Format 4
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Function
Reserved
Reserved
Start High)
Start High)
End High)
TL D 12302 – 11
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TL D 12302 – 7
TL D 12302 – 9