TDA5225 Datasheet, PDF (45/176 Pages) Infineon Technologies AG – Enhanced Sensitivity Multi-Channel Quad-Configuration Receiver

TDA5225
Functional Description
2.5.1.1 Control Interface
The control interface is used in order to configure the TDA5225 after start-up or to re-
configure it during run-time, as well as to properly react on changes in the status of the
receiver in the Application Controller’s firmware. The control interface offers a bi-
directional communication link by which
• configuration data is sent from the Application Controller to the TDA5225,
• the receiver provides status information (e.g. information about the source of a
received data stream, by reading out the interrupt status registers) as response to a
request it has received from the Application Controller, and
• the TDA5225 autonomously alerts the Application Controller that a certain,
configurable event has occurred (e.g. that a received signal is above a certain power
level).
Configuration and status information are sent via the 4-wire SPI interface as described
in Chapter 2.5.4. The configuration data determines the behavior of the receiver, which
comprises
• scheduling the inactive power-saving phases as well as the active receive phases,
• selecting the properties of the RF/IF interface configuration (e.g. carrier frequency
selection, filter settings),
• configuring the properties of a received message (e.g. if the received signal strength
is above a certain configurable RSSI threshold level).
Note that the TDA5225 receiver IC supports reception of multiple configuration sets on
multiple channels in a time-based manner without reconfiguration. Thus, the RF/IF
interface as well as the message properties support alternative settings, which can be
activated autonomously by the receiver as part of the scheduling process.
In contrast to the high-level interface used for communicating configuration instructions
and status information, alerts are emitted by the receiver on a digital output pin that may
trigger external interrupts in the Application Controller. Note that the alerting conditions
as well as the polarity of the output pin are configurable, see Chapter 2.5.3.
2.5.1.2 Data Interface
The data interface between the Application Controller and the TDA5225 receiver IC is
used for the transport of the received data, see Figure 22. The features of the data
interface depend on the selected mode of operation.
There are two possible receive modes:
• Transparent Mode - Matched Filter (TMMF)
• Transparent Mode - Raw Data Slicer (TMRDS)
Access points for these receive modes can be seen in Figure 15.
Data Sheet
45
V1.0, 2010-02-19