Memory Map and Registers

 

 

Table 20-19. GPTPAFLG Field Descriptions

 

 

 

 

 

 

Bit(s)

Name

 

 

Description

 

 

 

 

 

 

7–2

 

Reserved, should be cleared.

 

 

 

 

 

 

1

PAOVF

 

Pulse accumulator overflow flag. Set when the 16-bit pulse accumulator rolls over from

 

 

 

 

0xFFFF to 0x0000. If the GPTPACTL[PAOVI] bit is also set, PAOVF generates an

 

 

 

 

interrupt request. Clear PAOVF by writing a 1 to it. This bit is read anytime, write

 

 

 

 

anytime. (Writing 1 clears the flag; writing 0 has no effect.)

 

 

 

 

1

Pulse accumulator overflow

 

 

 

 

0

No pulse accumulator overflow

 

 

 

 

 

 

0

PAIF

 

Pulse accumulator input flag. Set when the selected edge is detected at the PAI pin.

 

 

 

 

In event counter mode, the event edge sets PAIF. In gated time accumulation mode,

 

 

 

 

the trailing edge of the gate signal at the PAI pin sets PAIF. If the PAI bit in GPTPACTL

 

 

 

 

is also set, PAIF generates an interrupt request. Clear PAIF by writing a 1 to it.

 

 

 

 

1

Active PAI input

 

 

 

 

0

No active PAI input

 

 

 

 

 

 

 

NOTE

When the fast flag clear all enable bit, GPTSCR1[TFFCA], is set, any access to the pulse accumulator counter registers clears all the flags in GPTPAFLG.

20.5.17 Pulse Accumulator Counter Register (GPTPACNT)

Field

Reset

R/W Address

15

0

PACNT

0000_0000_0000_0000

R/W

IPSBAR + 0x1A_001A, 0x1B_001B

Figure 20-19. Pulse Accumulator Counter Register (GPTPACNT)

 

 

Table 20-20. GPTPACR Field Descriptions

 

 

 

 

Bit(s)

Name

 

Description

 

 

 

 

15–0

PACNT

 

Contains the number of active input edges on the PAI pin since the last reset.

 

 

 

Note: Reading the pulse accumulator counter registers immediately after an active

 

 

 

edge on the PAI pin may miss the last count since the input first has to be synchronized

 

 

 

with the bus clock.

 

 

 

To ensure coherent reading of the PA counter, such that the counter does not

 

 

 

increment between back-to-back 8-bit reads, it is recommended that only word (16-bit)

 

 

 

accesses be used. These bits are read anytime, write anytime.

 

 

 

 

MOTOROLA

Chapter 20. General Purpose Timer Modules (GPTA and GPTB)

20-15

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Motorola MCF5281, MCF5282 user manual Pulse Accumulator Counter Register Gptpacnt, Gptpaflg Field Descriptions, Pacnt