Basic Operation
1530
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
Multi-Buffered Serial Peripheral Interface Module (MibSPI) with Parallel Pin
Option (MibSPIP)
28.2.9.2 ENA Signal Time-Out (Master Only)
The SPI in master mode waits for the hardware handshake signal (ENA) coming from the addressed slave
before performing a data transfer. To avoid stalling the SPI by a non-responsive slave device, a time-out
value can be configured using C2EDELAY. If the time-out counter overflows before an active ENA signal
is sampled, the TIMEOUT flag in the status register SPIFLG is set and the TIMEOUT flag in the status
field of the corresponding buffer is set.
NOTE:
When the chip select signal becomes active, no breaks in transmission are allowed. The
next arbitration is performed while waiting for the time-out to occur.
28.2.9.3 Data-Length Error
An SPI can generate an error flag by detecting any mismatch in length of received or transmitted data and
the programmed character length under certain conditions.
Data-Length Error in Master Mode
: During a data transfer, if the SPI detects a de-assertion of the
SPIENA pin (by the slave) while the character counter is not overflowed, then an error flag is set to
indicate a data-length error. This can be caused by a slave receiving extra clocks (for example, due to
noise on the SPICLK line).
NOTE:
In a master mode SPI, the data length error will be generated only if the SPIENA pin is
enabled as a functional pin.
Data-Length Error in Slave Mode
: During a transfer, if the SPI detects a de-assertion of the SPICS pin
before its character length counter overflows, then an error flag is set to indicate a data-length error. This
situation can arise If the slave SPI misses one or more SPICLK pulses from the master. This error in slave
mode implies that both the transmitted and received data were not complete.
NOTE:
In a slave-mode SPI, the data-length error flag will be generated only if at least one of the
SPICS pins are configured as functional, and are being used for selecting the slave.
28.2.9.4 Continuous Self-Test (Master/Slave)
During data transfer, the SPI compares its own internal transmit data with its transmit data on the bus. The
sample point for the compare is at one-half SPI clock after transmit point. If the data on the bus does not
match the expected value, the bit-error (BITERR) flag is set and an interrupt is asserted if enabled.
NOTE:
The compare is made from the output pin using its input buffer.