Spsck - Spi Serial Clock; Mosi - Master Data Out, Slave Data In; Miso - Master Data In, Slave Data Out; Ss - Slave Select - NXP Semiconductors MKL27Z128VFM4 Reference Manual

Chapter 35 Serial Peripheral Interface (SPI)
35.3.1 SPSCK — SPI Serial Clock
When the SPI is enabled as a slave, this pin is the serial clock input. When the SPI is
enabled as a master, this pin is the serial clock output.
35.3.2 MOSI — Master Data Out, Slave Data In
When the SPI is enabled as a master and SPI pin control zero (SPC0) is 0 (not
bidirectional mode), this pin is the serial data output. When the SPI is enabled as a slave
and SPC0 is 0, this pin is the serial data input. If SPC0 is 1 to select single-wire
bidirectional mode, and master mode is selected, this pin becomes the bidirectional data
I/O pin (MOMI). Also, the bidirectional mode output enable bit determines whether the
pin acts as an input (BIDIROE is 0) or an output (BIDIROE is 1). If SPC0 is 1 and slave
mode is selected, this pin is not used by the SPI and reverts to other functions (based on
chip configuration).
35.3.3 MISO — Master Data In, Slave Data Out
When the SPI is enabled as a master and SPI pin control zero (SPC0) is 0 (not
bidirectional mode), this pin is the serial data input. When the SPI is enabled as a slave
and SPC0 is 0, this pin is the serial data output. If SPC0 is 1 to select single-wire
bidirectional mode, and slave mode is selected, this pin becomes the bidirectional data
I/O pin (SISO), and the bidirectional mode output enable bit determines whether the pin
acts as an input (BIDIROE is 0) or an output (BIDIROE is 1). If SPC0 is 1 and master
mode is selected, this pin is not used by the SPI and reverts to other functions (based on
chip configuration).
35.3.4 SS — Slave Select
When the SPI is enabled as a slave, this pin is the low-true slave select input. When the
SPI is enabled as a master and mode fault enable is off (MODFEN is 0), this pin is not
used by the SPI and reverts to other functions (based on chip configuration). When the
SPI is enabled as a master and MODFEN is 1, the slave select output enable bit
determines whether this pin acts as the mode fault input (SSOE is 0) or as the slave select
output (SSOE is 1).
KL27 Sub-Family Reference Manual , Rev. 5, 01/2016
Freescale Semiconductor, Inc. 573