SPIEN
SPICLK
SPIDAT[1]
SPIDAT[0]
Word
Word
Word
SPIEN
SPICLK
SPIDAT[0]
Word
Word
Word
Functional Description
Once the channel is enabled, the SPIEN signal is activated with the programmed polarity.
As in multi-channel master mode, the start of the transfer depends on the status of the transmitter register,
the status of the receiver register and the mode defined by the bits TRM in the configuration register
(transmit only, receive only or transmit and receive) of the enabled channel.
The status of the serialization completion of each SPI word is given by the bit EOT of the register
MCSPI_CH(I)STAT. The bit RX_full in the MCSPI_IRQSTATUS register is set when a received data is
loaded from the shift register to the receiver register.
A change in the configuration parameters is propagated directly on the SPI interface. If the SPIEN signal
is activated the user must insure that the configuration is changed only between SPI words, in order to
avoid corrupting the current transfer.
NOTE:
The SPIEN polarity, the SPICLK phase and SPICLK polarity must not be modified when the
SPIEN signal is activated. The Transmit/Receive mode, programmable with the bit TRM can
be modified only when the channel is disabled. The channel can be disabled and enabled
while the SPIEN signal is activated.
The delay between SPI words that requires the connected SPI slave device to switch from one
configuration (Transmit only for instance) to another (receive only for instance) must be handled under
software responsibility.
At the end of the last SPI word, the channel must be deactivated (MCSPI_CH(I)CTRL[En] is cleared to 0)
and the SPIEN can be forced to its inactive state (MCSPI_CH(I)CONF[Force]).
and
show successive transfers with SPIEN kept active low with a different
configuration for each SPI word in respectively single data pin interface mode and two data pins interface
mode. The arrows indicate when the channel is disabled before a change in the configuration parameters
and enabled again.
Figure 24-9. Continuous Transfers With SPIEN Maintained Active (Single-Data-Pin Interface Mode)
Figure 24-10. Continuous Transfers With SPIEN Maintained Active (Dual-Data-Pin Interface Mode)
4008
Multichannel Serial Port Interface (McSPI)
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated