Cirrus-logic CS4953xx Instrukcja Użytkownika Pobierz pdf (Strona 40)

I2C Port

CS4953xx Hardware User’s Manual

3.3.3.2 Performing a Serial I

C Write

Information provided in this section is intended as a functional description indicating how to use the

configured serial control port to perform a I

C write from an external device (master) to the CS4953xx

DSP (slave). The system designer must ensure that all timing constraints of the I

C write cycle are met

(see the CS4953xx datasheet for timing specifications). When writing to the CS4953xx, the same protocol

described in this section will be used when writing single-word messages to the boot firmware, writing

multiple-word overlay images to the boot firmware, and writing multiple-word messages to application

firmware. The examples given can therefor be expanded to fit any I

C writing situation.

The flow diagram shown in Figure 3-8 illustrates the sequence of events that define the I

C write protocol

for SCP1. Section 3.4.3.2..describes the Serial I

C Write protocol.

Figure 3-8. I

C Write Flow Diagram

MORE DATA?

SEND I2C START:

DRIVE SCP1_SDA LOW

WHILE SCP1_CLK IS

HIGH

WRITE ADDRESS BYTE

0x80

SEND DATABYTE

I2C STOP:

DRIVE SCP1_SDA HIGH

WHILE SCP1_CLK IS

HIGH

SCP1_BSY

(LOW)?

4 BYTES SENT?

SCP1_SDA ==

ACK?

EXIT (ERROR)

SCP1_SDA ==

ACK?

EXIT (ERROR)

1 2 ... 35 36 37 38 39 40 41 42 43 44 45 ... 117 118

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