DSP56857 datasheet(292/662 Pages) FREESCALE

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SPI Register Descriptions (SPI_BASE = $1FFFE8)

5685X Digital Signal Controller User Manual, Rev. 4

11-22

Freescale Semiconductor

11.11 SPI Register Descriptions (SPI_BASE = $1FFFE8)

Table 11-3 lists the SPI registers in ascending address, including the acronym, bit names, and

address of each register. These read/write registers should be accessed only with word accesses.

Accesses other than word lengths result in undefined results.

11.11.1 SPI Status and Control Register (SPSCR)

The SPSCR register:

•

Enables SPI module interrupt requests

•

Selects interrupt requests

•

Configures the SPI module as Master or Slave

•

Selects serial clock polarity and phase

•

Enables the SPI module Receive Data register full interrupt

•

Enables Transmits Data register empty interrupt

•

Selects Master SPI baud rate

Figure 11-14. SPI Status and Control Register (SPSCR)

See Programmer’s Sheets on Appendix page B-64

Note:

Using BFCLR or BFSET instructions to modify SPSCR can cause unintended side

effects on the status bits.

11.11.1.1 SPI Baud Rate Select Bits (SPR)—Bits 15–13

While in the Master mode, these read/write bits select one of eight baud rates depicted in Table

11-4. SPR2:0 have no effect in Slave mode. Reset clears SPR2:0 to b011. Use the formula below

to calculate the SPI baud rate.

SPR1 and SPR0 have no effect in Slave mode. Reset clears SPR1 and SPR0. Use the formula

below to calculate the SPI baud rate.

CLK = Peripheral Bus Clock BD = Baud Rate Divisor

Base + $0

Read

SPR

DSO ERRIE MODFEN SPRIE SPMSTR CPOL CPHA SPE SPTIE

SPRF OVRF MODF SPTE

Write

Reset

000

Baud Rate =

CLK

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