SPI Port
CS4953xx Hardware Users Manual
DS732UM7
Copyright 2008 Cirrus Logic, Inc
3-16
If the SPI transaction is a write from master to the CS4953xx (R/W = 0, Address = 0x80), then the master will clock
the SCP1_CLK signal and drive the SCP1_MOSI signal with data bytes for the CS4953xx to read. If the SPI
transaction is a read to the master from the CS4953xx (R/W = 1, Address = 0x81), then the master will drive the
SCP1_CLK signal and read the SCP1_MISO signal with the data bytes from the CS4953xx.
Figure 3-14. Address and Data Bytes
3.3.2.1 SCP1_BSY Behavior
The SCP1_BSY signal is not part of the SPI protocol, but it is provided so that the slave can signal to the master that
it cannot receive any more data. A falling edge of the SCP1_BSY signal indicates the master must halt transmission.
Once the SCP1_BSY signal goes high, the suspended transaction may continue. The host must obey the SCP1_BSY
pin or control data will be lost.
3.3.3 SPI Messaging
Messaging to the CS4953xx using the SPI bus requires usage of all the information provided in the SPI Bus
Description and Bus Dynamics above. For control and application image downloading, SPI transactions to the
CS4953xx will involve 4-byte words. A detailed description of the serial SPI communication mode is provided in
this section. This includes:
•
A flow diagram and description for a serial SPI write
•
A flow diagram and description for a serial SPI read
SCP1_CLK
SCP1_MOSI
7-bit SPI Address
Data Byte
SCP1_CS
R/W
SCP1_CLK
SCP1_MOSI
Data Byte
SCP1_CS
SCP1_MISO
R/W
7-bit SPI Address
Содержание CS4953xx
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