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Functional Description
NOTE: The turbo mode is also supported for the Keep SPIEN active mode when the following
conditions are met:
• A single channel will be explicitly used (bit MCSPI_MODULCTRL[Single] is set to 1).
• The turbo mode is enabled in the configuration of the channel (bit Turbo of the register
(i)CONF).
24.3.2.6.3 Turbo Mode
The purpose of the Turbo mode is to improve the throughput of the SPI interface when a single channel is
enabled, by allowing transfers until the shift register and the receiver register are full.
This mode is programmable per channel (bit Turbo of the register (I)CONF). When several channels are
enabled, the bit Turbo of the registers MCSPI_CH(I)CONF has no effect, and the channel access to the
shift registers remains as described in Section 24.3.2.3.
In Turbo mode, Rule 1 and Rule 2 defined in Section 24.3.2.3 are applicable but Rule 3 is not applicable.
An enabled channel can be scheduled if its receive register is full (bit RXS of the register
MCSPI_CH(I)STAT) at the time of shift register assignment until the shift register is full.
In Turbo mode, Rule 1 and Rule 2 defined in Section 24.3.2.3 are applicable but Rule 3 is not applicable.
An enabled channel can be scheduled if its receive register is full (bit RXS of the register
MCSPI_CH(I)STAT) at the time of shift register assignment until the shift register is full.
The receiver register cannot be overwritten in turbo mode. In consequence the RX_overflow bit, in
MCSPI_IRQSTATUS register is never set in this mode.
24.3.2.7 Start Bit Mode
The purpose of the start bit mode is to add an extended bit before the SPI word transmission specified by
word length WL. This feature is only available in master mode.
This mode is programmable per channel (bit Start bit enable SBE of the register MCSPI_CH(I)CONF).
The polarity of the extended bit is programmable per channel and it indicates whether the next SPI word
must be handled as a command when SBPOL is cleared to 0 or as a data or a parameter when SBPOL is
set to 1. Moreover start bit polarity SBPOL can be changed dynamically during start bit mode transfer
without disabling the channel for reconfiguration, in this case you have the responsibility to configure the
SBPOL bit before writing the SPI word to be transmitted in TX register.
The start bit mode could be used at the same time as turbo mode and/or manual chip select mode. In this
case only one channel could be used, no round-robin arbitration is possible.
4009
SPRUH73H–October 2011–Revised April 2013 Multichannel Serial Port Interface (McSPI)
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