NXP Semiconductors K22F series, Reference Manual, Page: 1129 / 1407

NOTE
Do not tie the SPI slave select pin to ground. Otherwise, SPI
cannot function properly.
45.2.2 PCS1–PCS3—Peripheral Chip Selects 1–3
Master mode: Peripheral Chip Selects 1–3 (O)—Select an SPI slave to receive data
transmitted by the module.
Slave mode: Unused
45.2.3 PCS4—Peripheral Chip Select 4
Master mode: Peripheral Chip Select 4 (O)—Selects an SPI slave to receive data
transmitted by the module.
Slave mode: Unused
45.2.4 PCS5/PCSS—Peripheral Chip Select 5/Peripheral Chip
Select Strobe
Master mode:
• Peripheral Chip Select 5 (O)—Used only when the peripheral-chip-select strobe is
disabled (MCR[PCSSE]). Selects an SPI slave to receive data transmitted by the
module.
• Peripheral Chip Select Strobe (O)—Used only when the peripheral-chip-select strobe
is enabled (MCR[PCSSE]). Strobes an off-module peripheral-chip-select
demultiplexer, which decodes the module's PCS signals other than PCS5, preventing
glitches on the demultiplexer outputs.
Slave mode: Unused
45.2.5 SCK—Serial Clock
Master mode: Serial Clock (O)—Supplies a clock signal from the module to SPI slaves.
Slave mode: Serial Clock (I)—Supplies a clock signal to the module from an SPI master.
Chapter 45 Serial Peripheral Interface (SPI)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 1129