As in 3-wire master mode, the TALK bit must be cleared to 0. Otherwise, the slave receives data normally.
Example 12-7. 3-Wire Slave Mode Receive
Uint16 rdata;
SpiaRegs.SPICTL.bit.TALK = 0; // Disable Transmit path
while(SpiaRegs.SPISTS.bit.INT_FLAG !=1) {} // Waits until data rx’d
rdata = SpiaRegs.SPIRXBUF; // Slave reads data
12.4.5 SPI STEINV Bit in Digital Audio Transfers
On those devices with two SPI modules, enabling the STEINV bit on one of the SPI modules allows the pair
of SPIs to receive both left and right-channel digital audio data in slave mode. The SPI module that receives
a normal active-low SPISTE signal stores right-channel data, and the SPI module that receives an inverted
active-high SPISTE signal stores left-channel data from the master. To receive digital audio data from a digital
audio interface receiver, the SPI modules can be connected as shown in
Note
This configuration is only applicable to slave mode (MASTER_SLAVE = 0). When the SPI is
configured as master (MASTER_SLAVE = 1), the STEINV bit will have no effect on the SPISTE
pin.
SPIB_STE
SPIB_SOMI
SPIB_SIMO
SPIB_CLK
SPI-B
SPI-A
SPIA_CLK
SPIA_SIMO
SPIA_SOMI
SPIA_STE
AUDIOBIT
CLK
L/R CLK
DA
T
A
OUT
DIGITAL
AUDIO
RECEiVER
Figure 12-11. SPI Digital Audio Receiver Configuration Using Two SPIs
Standard C28x SPI timing requirements limit the number of digital audio interface formats supported using
the 2-SPI configuration with the STEINV bit. See your device-specific data sheet electrical specifications for
SPI timing requirements. With the SPI clock phase configured such that the CLKPOLARITY bit is 0 and the
CLK_PHASE bit is 1 (data latched on rising edge of clock), standard right-justified digital audio interface data
format is supported as shown in
.
Serial Peripheral Interface (SPI)
778
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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