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Keith - many thanks for the reply. You are perfectly correct, of course - I was just having one of those 'I wonder what would happen if I did this ...' thoughts, when I was looking at powering-down memory devices into standby.
Having read your reply, my next line of thought last night was -...
I'm currently working on a Z80 controller design, and I'd like to get the power requirements down to something competitive with the Microchip PIC. A few tens of milliamps perhaps (?) - a tall order.
Power-down and standby circuitry is obviously highly relevant here, and it was while considering...
CMOS Z80 standby mode
I've been programming Z80s for more years than I'd willingly own up to, but have never been asked to use a cmos Z80 in standby (full power-down, no clock) mode before now.
According to the early data sheets the procedure seems straightforward enough - e.g. /HALT...
Just to add ....
one important difference is that during a cold start (aka cold boot - initial application of power), volatile memory cells will power-up in an unpredictable way such that their contents will contain random data, and any configurable ports etc. will power-up into either unknown...
Re: Sinewave frequency
Consider: using a 5V(ish) zener (min. thermal drift) to provide an interrupt trigger rather than zero crossing, and count over 2 half-cycles. If the voltage of the measured sinewave is high (relative to 5V) then the triggering point will occur on an almost vertical part...
Keeping the sine wave in it's unrectified form and using a zero-crossing detector is certainly favourite.
Having said that, detecting the *exact* zero voltage is actually quite difficult, as all semiconductors have some kind of minimum threshold voltage (p-n junction or similar).
A lot depends...
how much ram in pic16f877a
Suggest you consider 18F4520 (32k eeprom, 1.5k ram) or even 18F4620 (64k eeprom, 3.9k ram) if you have a memory-demanding application. These will drive at up to 40 Mhz and also have on-chip multiplication, both of which you might find useful in your application.
Regards
Re: Difficulties when programming "A-suffix" PICs
Well - there's nothing like answering your own post !!
I've now spent many hours on this issue, and - although I say this with due caution - it's just possible I may have unearthed the source of the problem with regard to the programming of 'A...
c compiler 18f452
just joined - looking through old threads - so very late on this one (!)
Check out MikroElectronika : they have compilers for C, Basic and Pascal.
They are free - with a 2k code limit. Good support forum.
**broken link removed**
http://www.mikroe.com/forum/index.php
Good...
As part of the process of transferring across from discrete microprocessors to the highly integrated MicroChip PIC devices, I've been searching the Web for any persistent problems related to these. One particular theme keeps cropping up regarding the programming of PICs - that of difficulties...
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