CS4970x4 Data Sheet

32-bit High Definition Audio Decoder DSP Family

DS752F1

13

5.9 Switching Characteristics — Serial Control Port - SPI Slave Mode

Figure 3. Serial Control Port - SPI Slave Mode Timing

Parameter

Symbol

Min

Typical

Max

Units

maximum speed of the communication port may be limited by the firmware application. Flow control using the SCP_

should be implemented to prevent overflow of the input data buffer. At boot the maximum speed is Fxtal/3.

2. When SCP1 is in SPI slave mode, very slow rise and fall times of the SCP_CLK edges may make the edges of the SCP_CLK

more susceptible to noise, resulting in non-smooth edges. Any glitch at the threshold levels of the SCP port input signals could

result in abnormal operation of the port. In systems that have noise coupling onto SCP_CLK, slow rise and fall times may cause

host communication problems. Increasing rise time makes host communication more reliable.

——

25

MHz

24

—

—

ns

20

—

—

ns

20

—

—

ns

Setup time SCP_MOSI input

5—

—

ns

Hold time SCP_MOSI input

5—

—

ns

——

11

ns

—

—

20

ns

0—

—

ns

24

—

—

ns

SCP_CS rising to SCP_MISO output high-Z

—20

—

ns

—

ns

SCP_BSY#

SCP_CS#

SCP_CLK

SCP_MOSI

SCP_MISO

SCP_IRQ#

0

12670

56

7

A6

A5

A0

R/W

MSB

LSB

MSB

LSB