Functional Description

 

15

14

13

12

 

11

10

9

8

Field

PM15

PM14

PM13

PM12

 

PM11

PM10

PM9

PM8

 

 

 

 

 

 

 

 

 

 

Reset

 

 

 

1111_1111

 

 

 

 

 

 

 

 

 

 

 

 

 

R/W

 

 

 

R/W

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7

6

5

4

 

3

2

1

0

Field

PM7

PM6

PM5

PM4

 

PM3

PM2

PM1

PM0

 

 

 

 

 

 

 

 

 

 

Reset

 

 

 

1111_1111

 

 

 

 

 

 

 

 

 

 

 

 

 

R/W

 

 

 

R/W

 

 

 

 

 

 

Address

IPSBAR + 0x0015_0002 and 0x0015_0003 (PIT0); 0x0016_0002 and 0x0016_0003 (PIT1); 0x0017_0002

 

and 0x0017_0003 (PIT2); 0x0018_0002 and 0x0018_0003 (PIT3)

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 19-3. PIT Modulus Register (PMR)

19.5.2.3PIT Count Register (PCNTR)

The 16-bit, read-only PCNTR contains the counter value. Reading the 16-bit counter with two 8-bit reads is not guaranteed to be coherent. Writing to PCNTR has no effect, and write cycles are terminated normally.

 

15

14

13

12

 

11

10

9

8

Field

PC15

PC14

PC13

PC12

 

PC11

PC10

PC9

PC8

 

 

 

 

 

 

 

 

 

 

Reset

 

 

 

1111_1111

 

 

 

 

 

 

 

 

 

 

 

 

 

R/W

 

 

 

R

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7

6

5

4

 

3

2

1

0

 

 

 

 

 

 

 

 

 

 

Field

PC7

PC6

PC5

PC4

 

PC3

PC2

PC1

PC0

 

 

 

 

 

 

 

 

 

 

Reset

 

 

 

1111_1111

 

 

 

 

 

 

 

 

 

 

 

 

 

R/W

 

 

 

R

 

 

 

 

 

 

Address

IPSBAR + 0x0015_0004 and 0x0015_0005 (PIT0), 0x0016_0004 and 0x0016_0005 (PIT1), 0x0017_0004

 

 

and 0x0017_0005 (PIT2), 0x0018_0004 and 0x0018_0005 (PIT3)

 

 

 

 

 

 

 

 

 

 

 

Figure 19-4. PIT Count Register (PCNTR)

19.6 Functional Description

This subsection describes the PIT functional operation.

19.6.1 Set-and-Forget Timer Operation

This mode of operation is selected when the RLD bit in the PCSR register is set.

When the PIT counter reaches a count of 0x0000, the PIF flag is set in PCSR. The value in the modulus register is loaded into the counter, and the counter begins decrementing toward 0x0000. If the PIE bit is set in PCSR, the PIF flag issues an interrupt request to the CPU.

19-6

MCF5282 User’s Manual

MOTOROLA

Page 420
Image 420
Motorola MCF5282, MCF5281 user manual Set-and-Forget Timer Operation, PIT Count Register Pcntr