Cirrus Logic CS4970x4 - Manual (Page 61)

2-15 Copyright 2013 Cirrus Logic, Inc. DS810UM6
I2C Port
CS4953x4/CS4970x4 System Designer’s Guide
2.5.3.2 Performing a Serial I
2
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
2
C write from an external device (Master) to the CS4953x4/
CS4970x4 DSP (Slave). The system designer must ensure that all timing constraints of the I
2
C write cycle
are met (see the CS4953x4/CS4970x4 datasheet for timing specifications). When writing to the
CS4953x4/CS4970x4, 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
2
C writing situation.
The flow diagram shown in Figure 2-14 illustrates the sequence of events that define the I
2
C write
protocol for SCP1. Section 2.5.3.3. .describes the Serial I
2
C Write protocol.
Figure 2-14. I
2
C Write Flow Diagram
MORE DATA?
SEND I2C START:
DRIVE SCP1_SDA LOW
WHILE SCP1_CLK IS
HIGH
WRITE ADDRESS BYTE
0x80
N
SEND DATABYTE
I2C STOP:
DRIVE SCP1_SDA HIGH
WHILE SCP1_CLK IS
HIGH
Y
SCP1_BSY
(LOW)?
N
Y
Y
N
4 BYTES SENT?
SCP1_SDA ==
ACK?
Y
N
EXIT (ERROR)
SCP1_SDA ==
ACK?
Y
N
EXIT (ERROR)