Device
spim_cs0
spim_somi
spim_simo
spim_clk
SIMO
SIMO
SIMO
SIMO
SCLK
SCLK
SCLK
SCLK
SOMI
SOMI
SOMI
SOMI
CS
CS
CS
CS
Generic
SPI master
device
Generic
SPI slave
device
Generic
SPI slave
device
Generic
SPI slave
device
mcspi-017
McSPI
module m
Public Version
www.ti.com
McSPI Functional Description
Figure 20-18. Example of McSPI Slave With One Master and Multiple Slave Devices on Channel 0
The channel 0 in slave mode has the following resources:
•
Its own channel enable, programmable with the SPIm.
[0] EN bit (with x=0). This
channel must be enabled before transmission and reception.
•
For this mode, the slave-select signal can be detected only on spin_cs0.
•
Its own transmitter register, SPIm.
(with x=0), on top of the common transmit shift register.
If the
register is empty, the SPIm.
[1] TXS bit (with x=0) is set. If McSPI
is selected by an external master (the active signal on the spim_csx port assigned to channel 0), the
register content of channel 0 is always loaded into the shift register, whether its content is
updated or not. The
register must be loaded before McSPI is selected by a master.
•
Its own receiver register, SPIm.
(with x=0), on top of the common receive shift register. If
the
register is full, the SPIm.
[0] RXS bit (with x=0) is set.
NOTE:
The
register and
registers of the other channels are not used.
Reading from or writing to a channel register other than channel 0 has no effect.
•
Its
own
communication
configuration
with
the
following
parameters
through
the
SPIm.
register (with x=0):
–
Transmit and receive modes, programmable with the TRM field
–
Interface mode (two data pins or single data pin) and data pins assignment, both programmable
with the IS and DPE bits. (The SPIm modules are in slave mode after reset and must be properly
configured for the modules to act in master mode.)
–
SPI word length, programmable with the WL bit
–
spim_csx polarity, programmable with the EPOL bit
–
spim_clk polarity, programmable with the POL bit
2999
SWPU177N – December 2009 – Revised November 2010
Multichannel SPI
Copyright © 2009–2010, Texas Instruments Incorporated