AM79C30AVC datasheet(26/101 Pages) AMD

26 / 101 page

Am79C30A/32A Data Sheet

6. The peak registers are double-buffered and can be

read asynchronously to the operation of the DSP

7. The peak registers default to “don't care” values

when the part is reset. An initial read operation is re-

quired to clear the register before using it for the first

time.

The PEAKX register is at indirect address 70H, while

the PEAKR register is at indirect address 71H. Both

may be accessed via back-to-back read data register

operations by loading the command register with 72H.

Tone Generators

The MAP contains three tone generators which can be

enabled via MAP Mode Register 2, bits 2, 3, and 4.

Only one of the three tone generator bits in the register

can be set at a time. If more than one bit is set, all three

bits are considered set to zero and tone generation is

disabled. The tone generators are:

DTMF Generator

This generator provides tone injection at a sampling

rate of 32 kHz into the transmit and sidetone paths (Fig-

ure 3, Block A). The DTMF frequencies generated are

guaranteed to ±1.2% deviation.

The DTMF generator may be used to generate single

frequency outputs. To obtain a single frequency out of

the DTMF generator, load a zero code into one of the

two frequency registers.

Tone Generation

This generator provides call progress tones to the re-

ceive path, where it is added to the incoming speech

(Figure 3, Block B).

Tone Ringer

This generator provides tone aler t signals output

through the receive path to the loudspeaker or ear-

piece (Figure 3, Block C).

To program the DTMF tone generators, two frequency

values and two amplitude values must be written to the

two 8-b it Frequ ency Ton e Gen era to r Re gisters

(FTGR1, FTGR2) and the two 8-bit Amplitude Tone

Generator Registers (ATGR1, ATGR2), respectively.

The Tone Generator and the Tone Ringer use the fre-

quency programmed in FTGR1. The Tone Generator

uses the amplitude programmed in ATGR1 while the

Tone Ringer uses the amplitude programmed in ATGR2.

Common frequency values are listed in Table 22.

The FTGR codes to obtain DTMF dialing output fre-

quencies are listed in Table 21.

Table 21.

DTMF Codes

9BH

ABH

BFH

D3H

FTGR 1 or 2

FREQ

1209

1336

1477

1633

5AH

697

63H

770

6EH

852

79H

941

HEX REG VALUE

FTGR 2 or 1

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