Re: [N8VEM: 15616]

[Sergey <skis...@gmail.com>]

49.98Hz - that exactly that I've mentioned before, your frequency
meter receives noise from power grid (50 Hz). It is not the valid
signal.
Not sure what CPU pin you're talking about. If it is on CLK (pin 6),
please check your CPU oscillator.

Thanks,
Sergey

On Feb 19, 12:18 pm, rbruinsma <rbma...@gmail.com> wrote:
> Op dinsdag 19 februari 2013 03:29:08 UTC+1 schreef Sergey het volgende:
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> > That is very similar multimeter to one I have. Yes, the frequency (Hz)
> > and duty cycle (%) measurements can be useful to detect pulses.
> > It looks like your multimeter can measure frequency of up to 5 MHz.
> > Which is should be more than enough for measuring signals on a 4 MHz
> > (or a 1.8432 MHz) clocked Z80. You can test it first by measuring
> > frequency on Z80 CLK input (pin 6). When you can try measuring
> > frequency on A0 and /MREQ. If I remember correctly /MREQ frequency
> > will be about 1/4 of the CLK frequency, and A0 is about 1/8 of CLK
> > frequency (assuming that Z80 executing NOPs).
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> > Sometimes you might get a 50 Hz (or 60 Hz for US and few other
> > countries) reading, it probably means that one of the leads is
> > floating / not connected, or a device under test has a pin in high
> > impedance state. This reading is the mains frequency that is received
> > by the multimeter leads :-)
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> > Thanks,
> > Sergey
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> > Strange things are happening over here ;) when I use the multimeter with
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> the Hz option I get 49.98Hz on the CPU pin, so far so good. But after that
> every pin I tough on the Z80 will give me the same 49.98Hz reading??
> I did a lot of reading on this forum and I think I need a logic analyzer to
> proceed debugging. Because I don't have a big budget to spend on a logic
> analyzer I think I have two options:
> - Open Workbench Logic Sniffer that Dave suggested in this thread
> - Sanalogichttp://www.ikalogicstore.com/product.php?id_product=11
>
> The last one does have user friendly software, since I'am quit new to this
> all I think this would be my best bet. Do you have any ideas about this?
> Thanks!