User's Guide

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Timer Registers

5.2 Timer Counter Registers (CNTHI and CNTLO)

The timer counter registers (CNTLO and CNTHI) are 32-bit wide registers that can be used in conjunction

to form a 64-bit counter, or separately as 32-bit counters. The use of these registers depends on the

configuration of the timer. In the 64-bit general-purpose timer mode and watchdog mode, the two registers

work as a single 64-bit counter (see Figure 14). The 64-bit counter increments when the timer is enabled

to count. The timer counter registers are cleared to 0 at reset. These two registers are shown in Figure 15

and described in Table 10 and are accessed via a separate address.

In a dual 32-bit timer mode, the counter registers work as separate 32-bit registers. These two register

pairs can be configured as chained or unchained.

A hardware reset clears both counter registers, but software resets do not affect them. When the

TIMLORS bit is cleared, CNTLO keeps its current value, and when the TIMHIRS bit is cleared, CNTHI

keeps its current value.

Figure 14. 64-Bit Timer Counter Register

63 32 31 0

CNTHI CNTLO

R/W-0 R/W-0

LEGEND: R/W = Read/Write; -n = value after reset

Figure 15. Timer Counter Registers (CNTHI and CNTLO)

31 0

CNT

R/W-0

LEGEND: R/W = Read/Write; -n = value after reset

Table 10. Timer Counter Registers (CNTHI and CNTLO) Field Descriptions

Bit Field Value Description

31-0 CNT 00000000h - Counter register. This register is a 32-bit prescale counter or 32-bit timer counter, or one

FFFFFFFFh half of a 64-bit timer counter.

SPRU818B–December 2005–Revised September 2010 C6472/TCI648x 64-Bit Timer

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