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PostPosted: Tue Oct 08, 2013 9:57 pm 
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Joined: Mon Aug 05, 2013 10:43 pm
Posts: 258
Location: Southampton, UK
This might be covered somewhere.... Apologies if this is so.

I was wondering if someone had any tips for a simple beeper circuit, driven from a 6522? Pitch and duration will of course be under software driven control so my little computer wont be able to do anything while it's beeping, but it could be a nice edition to my (ahem) 6809 machine.

Somewhere in my parts drawer I have a little speaker in an enclosure, like you would have in a telephone. I was hoping to use that. I'm assuming this involves a transistor or two, which I have to say scares me. :)

Cheers!

Lawrence

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PostPosted: Tue Oct 08, 2013 10:00 pm 
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Joined: Fri Aug 30, 2002 1:09 am
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Just connect the piezoelectric element from PB7 of the VIA to ground, and set up the VIA to toggle PB7 every time T1 rolls over. The software sets the T1 latches to get the desired period (and therefore the frequency), and then just tell it when to start and stop, and the processor can be doing something else while you're beeping. No loop needed. It's Tip #17 at viewtopic.php?f=7&t=342&start=17 in the "Tip of the Day" topic.

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PostPosted: Wed Oct 09, 2013 12:03 pm 
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I shall give this a go and get back to you. I hadn't realised the timer was so flexible; excellent!

Thanks. :)

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PostPosted: Wed Oct 09, 2013 7:30 pm 
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Joined: Thu May 28, 2009 9:46 pm
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Aslak3 wrote:
I shall give this a go and get back to you. I hadn't realised the timer was so flexible; excellent!

Thanks. :)

Timers can do lots of cool stuff. If you're really ambitious (and have time to waste) figure out how to vary the timer rate via a periodic interrupt. You'll drive everyone within earshot bonkers. :lol:

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