TDA7529 datasheet(29/60 Pages) STMICROELECTRONICS

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TDA7529

Tuning state machine

29/60

Tuning state machine

Frequency changes in a system employing the TDA7529 can be efficiently performed using

a built-in state machine which simplifies the microprocessor supervisory functions. The state

machine, which can work in 8 different modes, can be invoked by a simple WRITE operation

into the tuner registers and, provided that the frequency to be jumped to has been pre-

loaded into the front-end registers through a previous separate or is loaded through a

concurrent WRITE operation, the FE jump sequence is automatically managed and flags

are provided to the back-end to indicate the current condition.

5.1

Tuning state machine modes

Hereafter the description of the 8 modes can be found. They are chosen by Byte 12

bits<6:4>.

The diagrams depicting the FE and flag conditions for each of the 8 modes are as follows:

5.1.1

Mode 000: buffer (nil)

When this mode is selected, no action is undertaken by the state machine.

5.1.2

Mode 001: preset

Figure 8.

Preset timing diagram

This mode is used to jump to a different frequency and stay there, with reception at the end

of the sequence.

AFSAMPLE can be used to tell the back-end when to mute and to unmute the audio output.

The 60 ms mute time (programmable) after the PLL has reached the locked condition can

be used to check the RDS signal presence and content in addition to the analog quality

information.

AFHOLD can be used to tell the back-end to switch to faster time constants for quick quality

acquisition.

EVENTS

TIME

transmission with subaddr. bit 7 = 1

wait T1ms

wait for Tplllock

wait 50 us

wait T60ms

AFSAMPLE

AFHOLD

B.E. OPERATION

mute audio

quality dets in fast mode

unmute audio

bus

STOP

event

regs

swap

AC00045

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