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COP and RTI Module

11.2.1 COP and RTI Control Register (COPCTL)

The COP and RTI Control (COPCTL) register is a 16-bit read/write register used to program both the COP timer and the RTI timer. The COPCTL register is reset to $0000 on hardware reset. When changing the bits in this register, it is important to follow the guidelines in Section 11.3, “Programming the COP and RTI Timers.” The bits of this register are defined in Section 11.2.1.1, “COP Enable (CPE)—Bit 15,” through Section 11.2.1.8, “RTI/COP Divider (DV[7:0])—Bits 7–0.”

NOTE:

The COPCTL register cannot be written unless preceded by the sequence documented in Section 11.3, “Programming the COP and RTI Timers.” This ensures that the COPCTL register cannot be modified if the computer is not operating properly. The COPCTL register can be read at any time.

11.2.1.1 COP Enable (CPE)—Bit 15

The COP enable (CPE) control bit enables the COP timer functionality. Both the RTE bit and the CPE bit must be set for the COP timer to function. The CPE bit is cleared on hardware reset.

NOTE:

When set, the COP timer disable (COPDIS) bit in the OnCE control register (OCR) overrides the CPE bit. See Section 12.4.4.1, “COP Timer Disable (COPDIS)—Bit 15,” on page 12-14 for more information.

11.2.1.2 COP Timer Divider (CT)—Bit 14

The COP timer divider (CT) control bit is used to program the division ratio for the COP timer. The CT bit is cleared on hardware reset. Table 11-1 shows how this bit is set.

Table 11-1. COP Timer Divider Definition

CT

Division

 

 

 

 

0

/8

 

 

1

/64

 

 

11.2.1.3 Reserved Bits—Bits 13–12

Bits 13–12 are reserved and are read as zero during read operations. These bits should be written with zero for future compatibility.

11.2.1.4 RTI Timer Enable (RTE)—Bit 11

The RTI timer enable (RTE) control bit is used to enable the RTI and COP timer functionality. The RTI timer can operate without the CPE bit being set, but both the RTE bit and the CPE bit must be set for the COP timer to operate. The RTE bit is cleared on hardware reset.

NOTE:

Clearing the RTE bit disables the input clock to both the RTI timer and COP timer, and can be used to reduce power consumption in systems that do not require these functions.

11-4

DSP56824 User’s Manual

 

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