TDA7437N

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TRANSMITTED DATA (SEND MODE)

bit

P = 0

Pause active

bit

P = 1

No pause detected

bit

ZM = 1 Zero cross mute ON

bit

ZM = 0 Zero cross mute OFF

bit

SM = 1 Soft mute ON

bit

SM = 0 Soft mute OFF

bit

ST = 1 Stereo signal detected (input MPX)

bit

ST = 0 Mono signal detected (input MPX)

The TDA7437N allows the reading of four info bits.

The type (Stereo/Mono) of received broadcasting signal is easily checked and displayed by using the ST bit.

The P bit check is useful in tuning jumps without signal muting.

The SM soft mute status becomes active immediately, when bit D0 is set to 1 (soft mute ON, MUTE byte) and

not when the signal level has reached the 60 dB final attenuation.

The optional Autoincrement mode allows to refresh all the bytes registers with transmission of a single subad-

dress, reducing drastically the total transmission time.

Without autoincrement, subaddress bit I = 0, to refresh all the bytes registers (10), it is necessary to transmit 10

times the chip address, the subaddress and the data byte.

Working with a 100Kb/s clock speed the total time would be :

[(9*3+2)*10]bits*10us=2.9ms

Instead using autoincrement mode, subaddress bit I=1, the total time will be:

(9*12+2)*10us=1.1ms.

The autoincrement mode is useful also to refresh partially the data. For example to refresh the 4 speakers at-

tenuators it is possible to program the subaddress Spkr LF (code XX010100), followed by the data byte of SPKR

LF, LR, RF, RR in sequence.

Note:that the autoincrement mode has a module 16 counter, whereas the total used register bytes are 10.

It is not correct to refresh all the 10 bytes starting from a subaddress different than XX010000.

For example using subaddress XX010010 (volume) the registers from Volume to Mute (see pag. 8) are correctly

updated but the next two transmitted bytes instead to refer to the wanted Input selector and Loudness are dis-

charged. (the solution in this case is to send two separated pattern in autoinc mode, the first composed by ad-

dress, subaddress XX010010, 8 data bytes, and the second composed by address, subaddress XX010000, 2

data bytes).

With autoincrement disabled, the protocol allows the transmission in sequence of N data bytes of a specific reg-

ister, without necessity to resend each time the address and subaddress bytes.

This feature can be implemented, for example, if a gradual Volume change has to be performed (the MCU has

not to send the STOP condition, keeping active the TDA7437N communication)

WARNING

The TDA7437N always needs to receive a STOP condition, before beginning a new START condition. The de-