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SPIx_C1 field descriptions (continued)
Field
Description
3
CPOL
Clock Polarity
Selects an inverted or non-inverted SPI clock. To transmit data between SPI modules, the SPI modules
must have identical CPOL values.
This bit effectively places an inverter in series with the clock signal either from a master SPI device or to a
slave SPI device. Refer to the description of “SPI Clock Formats” for details.
0
Active-high SPI clock (idles low)
1
Active-low SPI clock (idles high)
2
CPHA
Clock Phase
Selects one of two clock formats for different kinds of synchronous serial peripheral devices. Refer to the
description of “SPI Clock Formats” for details.
0
First edge on SPSCK occurs at the middle of the first cycle of a data transfer.
1
First edge on SPSCK occurs at the start of the first cycle of a data transfer.
1
SSOE
Slave Select Output Enable
This bit is used in combination with the Mode Fault Enable (MODFEN) field in the C2 register and the
Master/Slave (MSTR) control bit to determine the function of the SS pin.
0
When C2[MODFEN] is 0: In master mode, SS pin function is general-purpose I/O (not SPI). In slave
mode, SS pin function is slave select input.
When C2[MODFEN] is 1: In master mode, SS pin function is SS input for mode fault. In slave mode,
SS pin function is slave select input.
1
When C2[MODFEN] is 0: In master mode, SS pin function is general-purpose I/O (not SPI). In slave
mode, SS pin function is slave select input.
When C2[MODFEN] is 1: In master mode, SS pin function is automatic SS output. In slave mode: SS
pin function is slave select input.
0
LSBFE
LSB First (shifter direction)
This bit does not affect the position of the MSB and LSB in the data register. Reads and writes of the data
register always have the MSB in bit 7 (or bit 15 in 16-bit mode).
0
SPI serial data transfers start with the most significant bit.
1
SPI serial data transfers start with the least significant bit.
35.4.5 SPI Match Register low (SPIx_ML)
This register, together with the MH register, contains the hardware compare value. When
the value received in the SPI receive data buffer equals this hardware compare value, the
SPI Match Flag in the S register (S[SPMF]) sets.
In 8-bit mode, only the ML register is available. Reads of the MH register return all
zeros. Writes to the MH register are ignored.
Memory map/register definition
KL27 Sub-Family Reference Manual , Rev. 5, 01/2016
582
Freescale Semiconductor, Inc.