T8531TLDB Agere Systems, Inc., T8531TLDB Datasheet - Page 21

• Manufacturer Part Number: T8531TLDB
• Description: CODEC, AMuLaw CODEC, Line Card Signal Processor for CODEC Chip Set, 64TQFP
• Manufacturer: Agere Systems, Inc.

February 2002
Chip Set Functional Description
(continued)
T8531 Reset and Start-Up
Internal Reset
Internal reset is defined as the process that starts
when the internal reset line is brought low. This hap-
pens as a consequence of hardware (RTSB) or soft-
ware (BCW1) reset. The internal reset process
performs the following functions:
1. The frequency synthesizer does not receive any
2. The T8531 custom logic jams all resettable latches,
3. The DSP engine is held in reset state.
4. The internal reset line is held low for a minimum of
5. When the internal reset line goes high and the EXM
6. At the rising edge of the internal reset line, all the
Reset of the T8532 Devices
There are two options for reset of the T8532 chips.
The T8532s can make use of the same hardware reset
pulse as the T8531. The T8531 supplies OSCK to the
T8532s as soon as it is available, i.e., before the hard-
ware reset has gone away. It is recommended that
hardware reset be applied to all chips simultaneously.
Alternatively, the T8532s can be reset through software
reset (Tables 21 and 22), which is generated by the
external controlling device and routed to the T8532s via
the T8531. This can only occur when OSCK is guaran-
teed to be valid, i.e., not within 10 ms of power-on hard-
ware reset.
Agere Systems Inc.
reset signal, and is thus unaffected by reset. Follow-
ing power-on reset of the T8531, the frequency syn-
thesizer takes the mode determined by the
SCKSEL pin.
counters, and registers to their default values. No
data is latched on any of the T8531 interfaces during
internal reset.
18 ms to allow the frequency synthesizer to reach its
final accuracy. An internal counter is started when
the internal reset line goes low. It counts 80 frame
sync pulses on SFS before releasing the internal
reset line.
(internal) signal is held low, the DSP engine begins
its start-up routine by fetching the first instruction
from location 0 of the internal ROM.
T8531 custom logic blocks commence their normal
operation.
(continued)
Start-Up After Internal Reset
There is a specific sequence of microprocessor inter-
face instructions that must be followed after internal
reset in order to properly configure the T8531 and
T8532s for normal operation.
1. If nondefault values are required, the T8531 board
2. The 16 TSA RAM locations must be written before
3. The all channel test register must be set for normal
4. The T8531 control registers must be set. All
5. The amplitude of the calibration sine wave must be
6. All 16 channels must be put into initialization mode
7. The DSP engine RAM address 0x0002 must be set
8. After 70 ms, all 16 T8532 channels must be put into
9. The DSP engine RAM address 0x0002 must be set
10. After 70 ms, both T8532s should be sent a soft
control word 1 (address 0x1FFE) must be updated.
0x1FFC. CTZ must be disabled (see Table 20B).
operation (addresses 0x1510 and 0x1550 set to
0x0004).
16 channels must be powered up (addresses
0x1500—0x1507 and 0x1540—0x1547 must be set
to 0x8000).
set by writing address 0x0580 to coefficient
0xAA20, and address 0x0581 to coefficient
0xF49D.
(addresses 0x1518—0x151F and 0x1558—0x155F
must be set to 0x0080).
to 0x0700 to begin the first part of the T8532 cali-
bration start-up sequence.
loopback mode (addresses 0x1508—0x151F and
0x1548—0x154F must be set to 0x8001).
to 0x0720 to begin the second part of the T8532
calibration start-up sequence.
reset (addresses 0x1517 and 0x1557 set to
0x8000) and the all channel test register should be
set for normal operation (addresses 0x1510 and
0x1550 set to 0x0004). Normal T8531 operation
commences with the next SFS frame sync. The
chips are now ready for channels to be enabled and
filter coefficients to be set.
Codec Chip Set
21