ucb1100 NXP Semiconductors, ucb1100 Datasheet - Page 24

• Manufacturer Part Number: ucb1100
• Description: Advanced Modem/audio Analog Front-end
• Manufacturer: NXP Semiconductors

Philips Semiconductors
6.7.2 Codec Data Transfer
The audio and telecom codecs both operate at a programmable sample rate slower than the data transfer rate of the serial bus. The codecs
sample the contents of the appropriate field each time their internal counters indicate that a new sample is necessary. They update the data
read by the serial interface in the same manner. The counters for the audio and telecom subsystems are reset each time the respective
subsection is turned on (whenever the audio/telecom input or output path enable bits are set) and counting begins at the next SIBSync input
pulse (see Figure 26). The controlling devices must be both frequency and phase synchronized to the sample rate counters within the UCB1100
in order to ensure correct operation.
The codec data is loaded in the codec input register after the sub frame has been sent completely, when the appropriate data valid flag was set
in the sib frame. The codec input data is not refreshed, whenever the audio and/or telecom data valid flag equals ‘0’ in the sub frame or when no
sibdin data is transmitted.
Codec data must be received by the UCB1100 in one of the SIB frames preceding the sample moment of the codec, it uses the last sample
received before the sample moment. In case no refreshed codec data has been sent, the UCB1100 re-uses the available ‘old’ codec data
sample. This will lead to high distortion in the codec circuits.
1998 May 08
codec input data
Figure 26. Start of the codec sample counters (divisor set to 7). Sibdin sub frame #1 contains the codec input and/or output path
Advanced modem/audio analog front-end
sibdin stream
sample counter
sibclk/128
Figure 27. Codec input data handshake protocol, sibdin frame #1 contains codec data and the data valid flag equals ‘1’,
codec enable
sample pulse
sibclk/128
sibdin
enable bit, the codec enable signal is the ‘OR’ function of the associated code input and output enable bit.
#1
sib frame #2 contains codec data, but the data valid flag equals ‘0’, sib frame #3 contains no data.
N
#1
#1
N+1
#1
tcodstr
0
1
2
3
#2
4
5
6
N+2
0
#2
1
2
24
3
4
5
#1
6
0
1
N+3
2
#1
3
4
5
6
#3
0
1
2
N+4
3
#3
4
Preliminary specification
5
UCB1100
6
0
#1
1
SN00151
2
SN00152
3
N+5