G E N M o d u l e

Timer Status registers

Address: FFB0 0014 / FFB0 001C

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Rsvd

TIP

 

Reserved

 

TCLK

 

 

 

 

CTC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CTC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Register bit assignment

Bits

Access

Mnemonic

Reset

Description

 

 

 

 

 

D31

N/A

Reserved

N/A

N/A

 

 

 

 

 

D30

R/C

TIP

0

Timer interrupt pending

 

 

 

 

Set to 1 when the timer is enabled and the CTC

 

 

 

 

value counts down to 0. TIP generates an interrupt

 

 

 

 

to the CPU if the TIE bit in the Timer Control

 

 

 

 

register is set. Writing a 1 to the same bit position

 

 

 

 

in the Timer Status register clears the TIP bit.

 

 

 

 

Note: TIP is set immediately when the TE bit (in

 

 

 

 

the Timer Control register) is changed

 

 

 

 

from 0 to 1. An interrupt occurs

 

 

 

 

immediately after TE transitions from 0 to

 

 

 

 

1. If this initial interrupt causes a problem

 

 

 

 

in any specific application, the software

 

 

 

 

must be designed to ignore the first

 

 

 

 

interrupt after TE transitions from 0 to 1.

 

 

 

 

 

D29:27

N/A

Reserved

N/A

N/A

 

 

 

 

 

D26:00

R

CTC

O

Current timer count

 

 

 

 

Each time the CTC field reaches zero, the TIP bit is

 

 

 

 

set and the CTC is reloaded with the value defined

in the ITC field. The CTC continues to count back down to zero.

Table 28: Timer Status registers bit definition

w w w . d i g i . c o m

7 3

Page 87
Image 87
Digi NS7520 manual Address FFB0 0014 / FFB0 001C, Timer Status registers bit definition, Timer interrupt pending