Functional Description - NXP Semiconductors freescale KV4 Series Reference Manual

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This field is reserved.

This read-only field is reserved and always has the value 0.

CMD FIFO Counter

Indicates the number of entries in the CMD FIFO. The CMDCTR is incremented every time the command

part of PUSHR is written. The CMDCTR is decremented every time a SPI command is executed (all data

frames due to current command frame have been transmitted).

Command Next Pointer

Indicates which CMD FIFO Entry is used during the next transfer. The CMDNXTPTR field is updated

every time SPI data due to current command have been transmitted.

44.5 Functional description

The module supports full-duplex, synchronous serial communications between MCUs

and peripheral devices. The SPI configuration transfers data serially using a shift register

and a selection of programmable transfer attributes.

The module has the following configuration

• The SPI Configuration in which the module operates as a basic SPI or a queued SPI.

The DCONF field in the Module Configuration Register (MCR) determines the module

Configuration. SPI configuration is selected when DCONF within SPIx_MCR is 0b00.

The CTARn registers hold clock and transfer attributes. The SPI configuration allows to

select which CTAR to use on a frame by frame basis by setting a field in the SPI

Clock and Transfer Attributes Register (In Master Mode) (SPI_CTARn)

information on the fields of CTAR registers.

Typical master to slave connections are shown in the following figure. When a data

transfer operation is performed, data is serially shifted a predetermined number of bit

positions. Because the modules are linked, data is exchanged between the master and the

slave. The data that was in the master shift register is now in the shift register of the

slave, and vice versa. At the end of a transfer, the Transfer Control Flag(TCF) bit in the

Shift Register(SR) is set to indicate a completed frame transfer.

Freescale Semiconductor, Inc.

SPI_SREX field descriptions (continued)

KV4x Reference Manual, Rev. 2, 02/2015

Chapter 44 Serial Peripheral Interface (SPI)