AM79C32A Advanced Micro Devices, AM79C32A Datasheet - Page 26

• Manufacturer Part Number: AM79C32A
• Description: Digital Subscriber Controller (DSC) Circuit
• Manufacturer: Advanced Micro Devices

6. The peak registers are double-buffered and can be
7. The peak registers default to “don't care” values
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.
26
read asynchronously to the operation of the DSP
register. They are cleared on read.
when the part is reset. An initial read operation is re-
quired to clear the register before using it for the first
time.
FTGR 1 or 2
5AH
6EH
63H
79H
HEX REG VALUE
FTGR 2 or 1
FREQ
697
770
852
941
Am79C30A/32A Data Sheet
Table 21. DTMF Codes
1209
9BH
1
4
7
*
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.
1336
ABH
2
5
8
0
1477
BFH
3
6
9
#
1633
D3H
C
D
A
B