TMS320C54CST datasheet(32/171 Pages) TI

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Functional Overview

November 2001 − Revised September 2003

SPRS187B

Table 3−1. Processor Mode Status (PMST) Register Bit Fields (Continued)

BIT

DESCRIPTION

RESET

VALUE

NO.

DESCRIPTION

RESET

VALUE

NAME

SMUL

N/A

Saturation on multiplication. When SMUL = 1, saturation of a multiplication result occurs before

performing the accumulation in a MAC of MAS instruction. The SMUL bit applies only when OVM = 1

and FRCT = 1.

SST

N/A

Saturation on store. When SST = 1, saturation of the data from the accumulator is enabled before

storing in memory. The saturation is performed after the shift operation.

3.6

On-Chip Peripherals

The 54CST device has the following peripherals:

•

Software-programmable wait-state generator

•

Programmable bank-switching

•

A host-port interface (HPI8/16)

•

Three multichannel buffered serial ports (McBSPs)

•

Two hardware timers

•

A clock generator with a multiple phase-locked loop (PLL)

•

Enhanced external parallel interface (XIO2)

•

A DMA controller (DMA)

•

A UART with an integrated baud rate generator

•

An integrated DAA module

3.6.1 Software-Programmable Wait-State Generator

The software wait-state generator of the 54CST can extend external bus cycles by up to fourteen machine

cycles. Devices that require more than fourteen wait states can be interfaced using the hardware READY line.

When all external accesses are configured for zero wait states, the internal clocks to the wait-state generator

are automatically disabled. Disabling the wait-state generator clocks reduces the power consumption of

the 54CST.

The software wait-state register (SWWSR) controls the operation of the wait-state generator. The 14 LSBs

of the SWWSR specify the number of wait states (0 to 7) to be inserted for external memory accesses to five

separate address ranges. This allows a different number of wait states for each of the five address ranges.

Additionally, the software wait-state multiplier (SWSM) bit of the software wait-state control register (SWCR)

defines a multiplication factor of 1 or 2 for the number of wait states. At reset, the wait-state generator is

initialized to provide seven wait states on all external memory accesses. The SWWSR bit fields are shown

in Figure 3−5 and described in Table 3−2.

XPA

I/O

DATA

R/W-0

R/W-111

DATA

PROGRAM

R/W-111

LEGEND: R = Read, W = Write, 0 = Value after reset

Figure 3−5. Software Wait-State Register (SWWSR) [Memory-Mapped Register (MMR) Address 0028h]

TMS320C54CST Datasheet(PDF) 32 Page - Texas Instruments

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