DSP56303 datasheet(93/292 Pages) FREESCALE

93 / 292 page

DSP56303 User’s Manual, Rev. 2

Freescale Semiconductor

5-1

Programming the Peripherals

When peripherals are programmed in a given application, a number of possible modes and

options are available for use. Chapters 6 through 9 describe in detail the possible modes and

configurations for peripheral registers and ports. This chapter presents general guidelines for

initializing the peripherals. These guidelines include a description of how the control registers are

mapped in the DSP56303, data transfer methods that are available when the various peripherals

are used, and information on General-Purpose Input/Output (GPIO) configuration.

5.1 Peripheral Initialization Steps

Each peripheral has its own initialization process. However, all four peripherals share some

common steps, which follow:

Determine the Register values to be programmed, using the following steps:

Find the peripheral register descriptions in the manual.

Choose the appropriate modes to configure for a given application.

Determine the bit settings for programming those modes.

Make sure the peripheral is in individual reset state or disabled.

Note:

Peripheral registers should not be modified while the peripheral is active.

Configure the registers by writing the predetermined values from step 1 into the

appropriate register locations.

Enable the peripheral. Once the peripheral is enabled, it operates according the

programmed modes determined in step 1.

For detailed initialization procedures unique to each peripheral device, consult the initialization

section in the specific peripheral device chapter.

5.2 Mapping the Control Registers

The I/O peripherals are controlled through registers mapped to the top 128 words of X-data

memory ($FFFF80–$FFFFFF). Referred to as the internal I/O space, the control registers are

accessed by move (MOVE, MOVEP) instructions and bit-oriented instructions (BCHG, BCLR,

BSET, BTST, BRCLR, BRSET, BSCLR, BSSET, JCLR, JSET, JSCLR, and JSSET). The

DSP56303 датащи(PDF) 93 Page - Freescale Semiconductor, Inc