TP11368N datasheet(9/18 Pages) NSC

9 / 18 page

Functional Description (Continued)

CHANNEL NOP

Each channel can be independently disabled. When EN is at

logic low on the falling edge of CE, the ADPCM transcoder

processing for that channel is disabled. The processor re-

quires 4 CLK cycles for CE to maintain all channel variables.

The data output ports are also placed in known states. After

this the processor waits for the next interrupt. TSO outputs

the following data after a channel NOP:

TABLE 6. TSO at Channel NOP

QSEL1

QSEL0

Mode

TSO

32 kbps

0000

24 kbps

0000

16 kbps

0000

40 kbps

00000

The data pattern at TSO in

Table 6 are shown with four

ASCK clocks within the CE high pulse for the 32- , 24-,

16-kbps modes and five ASCK clocks within the CE high

pulse for the 40 kbps mode. In the case where ASCK pulses

are more than four or five, the given pattern recirculates with

the MSB first.

In the idle state, RSO outputs the following data (bit repre-

sentation with the sign-bit on the left followed by the MSB,

the sign-bit is the first bit after the rising edge of CE):

TABLE 7. RSO at Channel NOP

PCM1

Mode

RSO

8-Bit µ-Law

11111111

8-Bit A-Law

11010101

TP11368N Scheda tecnica(PDF) 9 Page - National Semiconductor (TI)