Registers
1464
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Serial Peripheral Interface (SPI)
29.3.18 SPI Data Format Registers (SPIFMTn)
The SPI data format registers (SPIFMT0, SPIFMT1, SPIFMT2, and SPIFMT3) are shown in
and described in
Figure 29-39. SPI Data Format Register (SPIFMTn)
31
30
29
24
Reserved
WDELAY
R-0
R/W-0
23
22
21
20
19
18
17
16
PARPOL
PARENA
WAITENA
SHIFTDIR
Reserved
DISCSTIMERS
POLARITY
PHASE
R/W-0
R/W-0
R/W-0
R/W-0
R-0
R/W-0
R/W-0
R/W-0
15
8
PRESCALE
R/W-0
7
5
4
0
Reserved
CHARLEN
R-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 29-26. SPI Data Format Register (SPIFMTn) Field Descriptions
Bit
Field
Value
Description
31-30
Reserved
0
Reads return zero and writes have no effect.
29-24
WDELAY
0-3Fh
Delay in between transmissions. Idle time that will be applied at the end of the current transmission
if the bit WDEL is set in the current buffer. The delay to be applied is equal to:
WDELAY × P
SPI module clock
+ 2 × P
SPI module clock
P
SPI module clock
-> Period of SPI module clock
23
PARPOL
Parity polarity: even or odd. PARPOL can be modified in privilege mode only.
0
An even parity flag is added at the end of the transmit data stream.
1
An odd parity flag is added at the end of the transmit data stream.
22
PARENA
Parity enable.
0
No parity generation/ verification is performed.
1
A parity is transmitted at the end of each transmit data stream. At the end of a transfer the parity
generator compares the received parity bit with the locally calculated parity flag. If the parity bits do
not match the PARERR flag is set in the corresponding control field. The parity type (even or odd)
can be selected via the PARPOL bit.
21
WAITENA
The master waits for SPIx_ENA signal from slave. WAITENA is considered in master mode only. In
slave mode this bit has no meaning. WAITENA enables a flexible SPI network where slaves with
SPIx_ENA signal and slaves without SPIx_ENA signal can be mixed.
0
The SPI does not wait for the SPIx_ENA signal from the slave and directly starts the transfer.
1
Before the SPI starts the data transfer it waits for the SPIx_ENA signal to become low. If the
SPIx_ENA signal is not pulled down by the addressed slave before the internal time-out counter
(C2EDELAY) overflows, then the master aborts the transfer and sets the TIMEOUT error flag.
20
SHIFTDIR
Shift direction.
0
Most significant bit is shifted out first.
1
Least significant bit is shifted out first.
19
Reserved
0
Reads return zero and writes have no effect.
18
DISCSTIMERS
Disable chip select timers for this format register. The C2TDELAY and T2CDELAY timers are by
default enabled for all the data format registers. Using this bit, these timers can be disabled for a
particular data format if not required. When a master is handling multiple slaves, with varied set-up
hold requirement, the application can selectively choose to include or not include the chip select
delay timers for any slaves.
0
Both C2TDELAY and T2CDELAY counts are inserted for the chip selects.
1
No C2TDELAY or T2CDELAY is inserted in the chip select timings.