ucb1200 NXP Semiconductors, ucb1200 Datasheet - Page 36

• Manufacturer Part Number: ucb1200
• Description: Advanced Modem/audio Analog Front-end
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Product specification
Advanced modem/audio analog front-end
UCB1200
Codec data transfer
The UCB1200 codec operates at samples which depend on the applied SIBCLK frequency and the programmed audio
and telecom divisors. The codec data transfer between the UCB1200 and the system controller has to be synchronized
with the UCB1200 sample counters and the SIB bus data transfer protocol to prevent conversion errors, resulting in high
distortion.
Correct codec data transfer is obtained easily when the UCB1200 is connected to one of the controllers in the PR3000
series, but the UCB1200 can also be connected to other controllers, if the following data protocol is used.
START OF CODEC DATA TRANSFER
The UCB1200 internal sample counters are started at the beginning of the first SIB frame following the SIB frame in which
the codec input and/or output path is enabled. This implies that the sample rate divisor has to be programmed before the
codec input and/or output path is enabled, Fig.31. Changing the sample rate on the fly, that is without disabling both the
codec input and output path before the divisor is reprogrammed, will disturb the codec data transfer synchronization
between the UCB1200 and its controller and is therefore not allowed.
ADCSYNC
SIBDIN
reg. 5 or 7
reg. 6 or 8
sample counter
0
1
2
3
4
5
6
7
8
0
1
2
3
4
5
6
7
8
0
1
2
sample frequency
Fig.31 Start-up sequence of the codec, TEL_DIV[n] = 9.
1998 Jul 22
36