TMS320DM640 datasheet(72/171 Pages) TI

72 / 171 page

Device Configurations

June 2003 − Revised August 2004

SPRS222C

2.3

Peripheral Configuration Lock

By default, the McASP0, VP0, VP1 [DM641 only], and I2C peripherals are disabled on power up. In order to

use these peripherals on the DM641/DM640 device, the peripheral must first be enabled in the Peripheral

Configuration register (PERCFG). Software muxed pins should not be programmed to switch

functionalities during run-time. Care should also be taken to ensure that no accesses are being

performed before disabling the peripherals. To help minimize power consumption in the DM641/DM640

device, unused peripherals may be disabled.

Figure 2−3 shows the flow needed to enable (or disable) a given peripheral on the DM641/DM640 devices.

Unlock the PERCFG Register

Using the PCFGLOCK Register

Write to

PERCFG Register

to Enable/Disable Peripherals

Read from

PERCFG Register

Wait 128 CPU Cycles Before

Accessing Enabled Peripherals

Figure 2−3. Peripheral Enable/Disable Flow Diagram

A 32-bit key (value = 0x10C0010C) must be written to the Peripheral Configuration Lock register

(PCFGLOCK) in order to unlock access to the PERCFG register. Reading the PCFGLOCK register

determines whether the PERCFG register is currently locked (LOCKSTAT bit = 1) or unlocked (LOCKSTAT

bit = 0), see Figure 2−4. A peripheral can only be enabled when the PERCFG register is “unlocked”

(LOCKSTAT bit = 0).

TMS320DM640 数据表(PDF) 72 Page - Texas Instruments