Registers
1463
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Serial Peripheral Interface (SPI)
29.3.17 SPI Default Chip Select Register (SPIDEF)
The SPI default chip select register (SPIDEF) is shown in
and described in
.
(1)
Not all devices support multiple slave chip select (SPIx_SCS[n]) pins, see your device-specific data manual for supported pins. If the pins
are not available, the corresponding bit is reserved and should be cleared to 0.
Figure 29-38. SPI Default Chip Select Register (SPIDEF)
31
16
Reserved
R-0
15
8
7
0
Reserved
CSDEF[
n
]
(1)
R-0
R/W-FFh
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 29-25. SPI Default Chip Select Register (SPIDEF) Field Descriptions
Bit
Field
Value
Description
31-8
Reserved
0
Reads return zero and writes have no effect.
7-0
CSDEF[
n
]
Chip select default pattern. The CSDEF field defines the state of the the SPIx_SCS[n] pins when no
transmissions are performed. The value of the CSDEF field is driven directly on the SPIx_SCS[n] pins.
Each bit in the CSDEF field corresponds to an SPIx_SCS[n] pin, for example, CSDEF[0] corresponds to
SPIx_SCS[0] (see your device-specific data manual to determine how many SPI pins are available on
your device).
The state of the chip select pins during a transmission is specified through the CSNR field in the SPI
transmit data register (SPIDAT1). The chip select pins can remain in their active state by setting the
CSHOLD bit in SPIDAT1 to 1. In slave mode, the CSDEF field should be set to FFh.
0
SPIx_SCS[n] pin is driven low.
1
SPIx_SCS[n] pin is driven high.