G E N m o d u l e r e g i s t e r s

Software Service register

Address: FFB0 000C

The Software Service register (SWSR) acknowledges the system watchdog timer. To do so, firmware must write ‘h5A and ‘hA5 to the register using two separate write operations. There is no restriction on the time between the two operations, but the operations must occur in the proper sequence with the proper data values.

The Software Service register can request a software reset of the NS7520 hardware. Firmware must write ‘h123 and ‘h321 to the register using two separate write operations. There is no restriction on the time between the two operations, and the two operations must occur in the proper sequence with the proper data values. The processor must be in supervisor mode for the second operation.

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SWSR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SWSR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Register bit assignment

Bits

Access

Mnemonic

Reset

Description

 

 

 

 

 

D31:00

W

SWSR

0

Software Service register

 

 

 

 

 

Table 26: Software Service register bit definition

Timer Control registers

Address: FFB0 0010 / FFB0 0018

Timers 1 and 2 provide the CPU with programmable interval timer(s). The timers use

the FXTALE timing reference and an optional 9-bit prescaler or the system clock. Each timer provides a 27-bit programmable-down counter mechanism.

The CPU loads an initial count register (ITC) to define the timeout period. When the current counter decrements to zero, the counter is reloaded. The reloading of the

7 0

N S 7 5 2 0 H a r d w a r e R e f e r e n c e , R e v . D 0 3 / 2 0 0 6

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Digi NS7520 manual Software Service register, Timer Control registers, Address FFB0 000C, Address FFB0 0010 / FFB0