LZ: Re:Timer interrupt when LCD is off?


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LZ: Re:Timer interrupt when LCD is off?




>Ess Andreas wrote:
>> 
>> Is that possible? Would be useful for several things, like real-time 
clocks, etc.
>> 
>>  Andreas
>> ----------------
>> E-Mail:  ess.andreas@computerhaus.at
>> Webpage: http://andi.ganymed.org

You know, I was just thinking about this last week.(the clock idea) But, 
I think you CAN do it with the LCD off... but not in HALT mode.
I think that all routines that turn off the calc first turn off the
LCD, then do a HALT command, which lowers the amp drain on the 
batteries, then only responds to interrupts. The thing is I'm not sure 
what kind of interrupts it checks for. You can do the clock but you 
would have to do this:

Interrupt:
;...turn on LCD...
;....clock routine....
;... check for on key
;this turns off the LCD:
 ld	a, $01
 out	($03), a
; res	0, ($06) ;you would do these two
; HALT           ;if you wanted to turn off the calc

This could be a huge battery drain(same as leaving on your calc all the 
time), maybe less because the LCD is off. I'm not sure how much batt 
life you save by turning off only the LCD. But I have another theory: 
maybe you can use the halt at the end of the interrupt, and turn on the 
whole calc at the beginning?
So in other words, you would be turning on and off the calc at 200hz or 
whatever. I'm not sure how this would affect the battery drain...
the only way to know for sure is to try it out...

If I'm way off here, somebody tell me. I'll look it up later today.

Terry

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