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COP and RTI Module

11.2.2 COP and RTI Count (COPCNT) Register

The COP and RTI Count (COPCNT) register is a 16-bit read-only register reflecting the value of the COP/RTI divider chain. The COPCNT register is written by the divider chain on the edge of the prescaler clock opposite that used to clock the divider chain. The COPCNT register can be read at any time.

11.2.2.1 Reserved Bits—Bits 15–13

Bits 15–13 are reserved and are read as zero during read operations.

11.2.2.2 RTI/COP Divider (DV[7:0])—Bits 12–5

When the COPCNT register is read, the RTI /COP divider (DV[7:0]) bits show the current value of the last divider in the RTI clock chain.

11.2.2.3 RTI Prescaler (RP[1:0])—Bits 4–3

When the COPCNT register is read, the RTI prescaler (RP[1:0]) bits show the current value of the prescaler portion of the RTI clock chain.

11.2.2.4 Scaler (SC[2:0])—Bits 2–0

When the COPCNT register is read, the scaler (SC[2:0]) bits show the current value of the scaler portion of the RTI clock chain.

11.2.3 COP Reset (COPRST) Register

The COP reset (COPRST) register is a 16-bit write-only register and is used for two purposes. The first use of this register is for resetting the COP timer before it times out. The COP timer, once enabled, can only be reset by writing a sequence in the correct order to the COPRST register. The required sequence is described in Section 11.3, “Programming the COP and RTI Timers.” This resets the COP timer to its maximum value, and it begins counting down again. The COP timer is the last divide-by-8 or divide-by-64 portion of the counter chain.

NOTE:

Writing to this register does not affect the portion of the timing chain shared by both the RTI and the COP timers.

The second use of this register is to enable writes to the COPCTL register. It is very important that the COPCTL register is not accidentally overwritten if the computer is not operating properly, so writes to this register are enabled only after a correct sequence is written to the COPRST register.

11-6

DSP56824 User’s Manual

 

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