Start Of Table Indicator; Pattern Descriptor Entries; Transmit Type Pattern Descriptor; Figure 17 Datagram Format - Infineon SP37 Function Manual

2.38.1.3

Start of Table indicator

The Start of Table is always the first byte of the PDT. The Start of Table is detailed in
Figure 17 Datagram format
Bits 4..0 - delayOSC - define the delay for the StartXtalOsc() used in the RF_Transmission routine. The delay is
calculated as (30 + delayOSC) x 42,67 µs. This delay is used as that for crystal oscillator startup, which takes place
before transmission of each repeated frame.
Bits 6..5 - not used - these bits should be set to 0.
Bit7 - V - enables the measurement of the battery voltage at the end of each transmitted frame, by means of the
ADC. Only the last measurement is stored into RAM and can be read by the application.
Note: In order to operate the ADC for battery voltage measurements, Start_Supply_Voltage() must be called
before Send_RF_Transmission is called. In order to read the measured supply voltage after the RF telegram
has completed, the Get_Supply_Voltage function may be called. Note that the ADC is enabled and in
standby mode during the duration of the Send_RF_Transmission function, therefore the total device current
consumption during RF transmission will exceed the value typically specified.
2.38.1.4

Pattern Descriptor entries

In general, the concept is to divide the RF telegram into blocks of similar bit encoding and modulation which can
be described by one Pattern Descriptor entry. A collection of Pattern Descriptors form the bulk of the PDT.
Consider the following example: an RF telegram with some number of Manchester coded Run-In (or "preamble")
bits, followed by a special Start of Message symbol (a "code violation") followed by the Manchester coded
Message Payload bits. The Run-In and Message Payload are transmitted bitwise (e.g. Manchester coded) while
the Start of Message symbol must be transmitted as chips because it is not Manchester coded data. The PDT for
this example consists of three Pattern Descriptors, appearing in the table in order of transmission. In addition to
Pattern Descriptors that define data and how it is transmitted, a "delay" type of Pattern Descriptor is also
supported. A Pattern Descriptor is composed of byte data in RAM and can be one of two types; a Transmit type
or a Delay type. Each of these Pattern Descriptor types is discussed in detail below.
2.38.1.5

Transmit Type Pattern Descriptor

A Transmit type Pattern Descriptor provides the RF Transmitter circuitry with serial data to encode and modulate.
The Transmit type is detailed in the figure below.
TRANSMIT TYPE PATTERN DESCRIPTOR
TYPE
Figure 18 Transmit Type Pattern Descriptor
ROM Library Function Guide
START of TABLE
bit bit bit
7 6 5
V R2F
n.u.
LENGTH
Tire Pressure Monitoring Sensor
bit bit bit
4 3 2
delayOSC
DATA
124
ROM Library Functions
Figure 17.
bit bit
1 0
DATA
Revision 1.0, 2011-12-15
SP37