TDA5235
Functional Description
Sensitivity in this transparent mode is significantly depending on the implemented clock
and data recovery algorithm of the user software in the application controller.
The data interface can be seen from Figure 51.
Self Polling capabilities are possible as well, but only Constant On-Off Mode and Wake-
up on RSSI makes sense. Assume one of the TDA5235 configurations (e.g.
Configuration B) is set for external data processing mode. See also example in
Figure 52. The needed On time (latency through TDA5235) is configured in the
corresponding On time registers of the chip. The interrupt for Wake-Up Config B (WUB)
is enabled and suitable RSSI thresholds are set.
If the RSSI signal is in a valid threshold area, the TDA5235 changes to Run Mode Self
Polling and an interrupt can be signaled to the Application Controller.
In case the RSSI signal is outside the valid threshold area, the chip stays in Self Polling
Mode and the external controller gets no interrupt (as the desired RSSI level is not
reached).
It should be mentioned that all Timeout Timers (TOTIMs) should be disabled in the
configuration set of the external processing mode as the microcontroller takes over the
control (see SFR bit group EXTPROC in the x_CHCFG register).
It is recommended to put this external configuration at the end of the On time within the
polling cycle (so right before the Off time). This is helpful when using the "EXTTOTIM"
command (goto Self Polling Mode, next configuration or Configuration A; see
Figure 77). When the external configuration is the last configuration before the Off time,
then the next configuration within the polling cycle would be the sequence of the Off time.
When data is available and the RSSI is within a valid threshold area, an interrupt is
generated (NINT). So the Application Controller can process the data and decide about
valid data.
In case the controller decides that wrong data was sent, the microcontroller can send the
register command "EXTTOTIM" (see Figure 77 and EXTPCMD register).
When the microcontroller detects valid data, then the controller can send the register
command "EXTEOM found" (see Figure 77 and EXTPCMD register) after completing
the data reception.
The functionality described above can also be used for other receive modes (mainly
TMMF, TMCDS), where the external microcontroller takes on responsibility for further
data processing.
Data Sheet
80
V1.0, 2010-02-19
INFINEON [ Infineon ]
