Delay Pattern Descriptor; End Of Table Pattern Descriptor; Figure 19 Delay Type Pattern Descriptor - Infineon SP37 Function Manual

The first byte ´TYPE´ of a Transmit type Pattern Descriptor specifies the encoding and modulation scheme for that
Pattern:
• 00 Manchester
H
• 01 Inverted Manchester
H
• 02 Differential Manchester
H
• 03 Biphase 0
H
• 04 Biphase 1
H
• 05 Chip Mode (at chiprate, i.e. double datarate)
H
• +00 for FSK Modulation
H
• +10 for ASK Modulation
H
So for example:
• 03 stands for Biphase 0 encoded data, FSK modulated
H
• 12 stands for Differential Manchester encoded data, ASK modulated
H
The second byte ´LENGTH´ specifies the length of the Pattern in bits (or chips in the case of TYPE = 05
LENGTH can be any value from 01
The remaining bytes in the Pattern Descriptor ´DATA´ contain the data which has to be encoded and transmitted.
Each byte in DATA is transmitted MSB first. In the case of a pattern with LENGTH that is not a multiple of eight,
the final remaining bits are transmitted MSB first from the final DATA byte.
2.38.1.6

Delay Pattern descriptor

A Delay type Pattern Descriptor serves to disable the RF Transmitter circuitry for either a fixed or pseudo-random
time delay. During Delay, the CPU is placed into IDLE mode to reduce overall current consumption. The Delay
type is detailed in Figure
Figure 19 Delay Type Pattern Descriptor
The first byte ´TYPE´ of a Delay type Pattern Descriptor is a fixed value of DD
The second byte ´DURATION´ specifies a fixed duration of delay time, in milliseconds [ms].
The third byte ´RANDOM´ specifies the maximum duration of a randomly generated delay time, in milliseconds
[ms]. The Random Delay will be uniformly distributed between 0 and the value of ´RANDOM´, in milliseconds [ms].
The total delay achieved with a Delay type Pattern Descriptor is the sum of the fixed and randomly generated delay
times. To realize a Pattern with a fixed delay time, simply set the DURATION byte accordingly and set the
RANDOM byte to zero. To realize a Pattern with a random delay time, set the DURATION byte and the RANDOM
byte accordingly: the result will be a fixed amount of time on the top of which a random delay is added.
The random delay is obtained using the SP37 Pseudo Random Number (PRN) generator peripheral. In order to
achieve some "randomness" between individual devices, it is recommended to seed the PRN generator with a
value unique to each device. e.g. the LSB of the Sensor ID.
2.38.1.7

End of Table pattern descriptor

A PDT must end with an End of Table (EOT) entry. In addition to marking the end of the table, the EOT allows for
one or more repetitions of the entire PDT. The EOT is detailed in
ROM Library Function Guide
(1 bit/chip) to FF
H
19.
DELAY TYPE PATTERN DESCRIPTOR
TYPE DURATION
Tire Pressure Monitoring Sensor
(255 bits/chips), and 00
H
RANDOM
Figure 20.
125
ROM Library Functions
(256 bits/chips).
H
.
H
Revision 1.0, 2011-12-15
SP37
or 15 ).
H H