Memory Map and Registers

20.5.14 GPT Channel Registers (GPTCn)

Field

Reset

R/W

Address

15

0

CCNT

0000_0000_0000_0000

R/W

IPSBAR + 0x1A_0010, 0x1A_0012, 0x1A_0014, 0x1A_0016,

0x1B_0010, 0x1B_0012, 0x1B_0014, 0x1B_0016

Figure 20-16. GPT Channel[0:3] Register (GPTCn)

Table 20-17. GPTCn Field Descriptions

Bit(s)

Name

Description

 

 

 

15–0

CCNT

When a channel is configured for input capture (IOSn = 0), the GPT channel registers

 

 

latch the value of the free-running counter when a defined transition occurs on the

 

 

corresponding input capture pin.

 

 

When a channel is configured for output compare (IOSn = 1), the GPT channel

 

 

registers contain the output compare value.

 

 

To ensure coherent reading of the GPT counter, such that a timer rollover does not

 

 

occur 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 (for the output compare

 

 

channel); writing to the input capture channel has no effect.

 

 

 

20.5.15 Pulse Accumulator Control Register (GPTPACTL)

Field

Reset

R/W

Address

7

6

5

4

3

 

0

PAE

PAMOD

PEDGE

CLK

PAOVI

PAI

 

 

 

 

 

 

 

0000_0000

R/W

IPSBAR + 0x1A_0018, 0x1B_0018

Figure 20-17. Pulse Accumulator Control Register (GPTPACTL)

Table 20-18. GPTPACTL Field Descriptions

Bit(s)

Name

 

Description

 

 

 

7

Reserved, should be cleared.

 

 

 

6

PAE

Enables the pulse accumulator.

 

 

1

Pulse accumulator enabled

 

 

0

Pulse accumulator disabled

 

 

Note: The pulse accumulator can operate in event mode even when the GPT enable

 

 

bit, GPTEN, is clear.

 

 

 

5

PAMOD

Pulse accumulator mode. Selects event counter mode or gated time accumulation

 

 

mode.

 

 

1

Gated time accumulation mode

 

 

0

Event counter mode

 

 

 

 

MOTOROLA

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

20-13

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Motorola MCF5281, MCF5282 user manual GPT Channel Registers GPTCn, Pulse Accumulator Control Register Gptpactl, Ccnt, Pae