Chapter 24 Multichannel Serial Port Interface (McSPI).
Chapter 24 Multichannel Serial Port Interface (McSPI).
Chapter 24 Multichannel Serial Port Interface (McSPI).
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
www.ti.com Functional Description<br />
Once the channel is enabled, the SPIEN signal is activated with the programmed polarity.<br />
As in multi-channel master mode, the start of the transfer depends on the status of the transmitter register,<br />
the status of the receiver register and the mode defined by the bits TRM in the configuration register<br />
(transmit only, receive only or transmit and receive) of the enabled channel.<br />
The status of the serialization completion of each SPI word is given by the bit EOT of the register<br />
MCSPI_CH(I)STAT. The bit RX_full in the MCSPI_IRQSTATUS register is set when a received data is<br />
loaded from the shift register to the receiver register.<br />
A change in the configuration parameters is propagated directly on the SPI interface. If the SPIEN signal<br />
is activated the user must insure that the configuration is changed only between SPI words, in order to<br />
avoid corrupting the current transfer.<br />
NOTE: The SPIEN polarity, the SPICLK phase and SPICLK polarity must not be modified when the<br />
SPIEN signal is activated. The Transmit/Receive mode, programmable with the bit TRM can<br />
be modified only when the channel is disabled. The channel can be disabled and enabled<br />
while the SPIEN signal is activated.<br />
The delay between SPI words that requires the connected SPI slave device to switch from one<br />
configuration (Transmit only for instance) to another (receive only for instance) must be handled under<br />
software responsibility.<br />
At the end of the last SPI word, the channel must be deactivated (MCSPI_CH(I)CTRL[En] is cleared to 0)<br />
and the SPIEN can be forced to its inactive state (MCSPI_CH(I)CONF[Force]).<br />
Figure <strong>24</strong>-9 and Figure <strong>24</strong>-10 show successive transfers with SPIEN kept active low with a different<br />
configuration for each SPI word in respectively single data pin interface mode and two data pins interface<br />
mode. The arrows indicate when the channel is disabled before a change in the configuration parameters<br />
and enabled again.<br />
Figure <strong>24</strong>-9. Continuous Transfers With SPIEN Maintained Active (Single-Data-Pin <strong>Interface</strong> Mode)<br />
SPIEN<br />
SPIDAT[0] Word Word Word<br />
SPICLK<br />
Figure <strong>24</strong>-10. Continuous Transfers With SPIEN Maintained Active (Dual-Data-Pin <strong>Interface</strong> Mode)<br />
SPIEN<br />
SPIDAT[0] Word Word<br />
SPIDAT[1]<br />
SPICLK<br />
Word<br />
SPRUH73E–October 2011–Revised May 2012 <strong>Multichannel</strong> <strong>Serial</strong> <strong>Port</strong> <strong>Interface</strong> (<strong>McSPI</strong>)<br />
Submit Documentation Feedback<br />
Copyright © 2011–2012, Texas Instruments Incorporated<br />
4135
Change language