CTRL & Tx
STAT & Rx
Seq.
SPISCS
[3:0]
TG 0 Trigger
TG 14 Trigger
CS decoder
RXBUF
SPISOMI
SPISIMO
SPICLK SPIENA
Buffer RAM
Shift Register
Parity
Basic Operation
1527
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
Multi-Buffered Serial Peripheral Interface Module (MibSPI) with Parallel Pin
Option (MibSPIP)
Figure 28-30. Multi-buffer in Slave Mode
When the SPIDAT1 register is updated, the enable signal is released, and the transaction could begin. If
the enable signal is not used, the master should wait for 6 VCLK cycles before sending the clock to begin
the transaction. This time allows the MibSPI to update the SPIDAT1 register.
Once the transaction is finished, the MibSPI writes back the content of the shift-register into the Rx buffer
and updates the status field.
NOTE:
If all the Transfer Groups are not needed, the number of SPICS pins that need to be in
functional mode could be reduced to 3, 2, or 1 by using the SPIPC0 register. In these cases,
the maximum number of Transfer Group accessible are, respectively 7, 3, and 1. The pins
that are set in GPIO mode are not decoded.
MibSPI in 3-pin and 4-pin (with SPIENA) mode also supports multi-buffer mode. However, it is restricted to
having just one transfer group, Transfer Group 0 (TG0). The entire multi-buffer RAM can be configured for
TG0 alone. The PSTART field in TG1CTRL register should be used to configure the size of the multi-
buffer (end of the buffers) for TG0.
NOTE:
The maximum input frequency on the SPICLK pin when in slave mode is VCLK frequency /2.
If the Slave is configured in either 3-pin or 4-pin (without SPIENA) modes, then, between end
of last SPICLK and the start of SPICLK for next buffer, there should be at least 6 VCLK
cycles of delay.