|
Ronald and yoda,
I agree, and a four channel logic analyzer is most a tease. Eight
can be helpful, 16 is much better and 34 is really grand but still
about a half dozen short to everything you might want to see at
once. 8 databits, 16 address bits, at 8 control lines, phi(clock),
M4, rd, wr, iorq, memrq,, a few chip selects. they add up fast.
Still if you keep tight focus, 8 can do a lot for you. It is a
shame that the Saleae 16 channel unit is $300. The Saleae user
interface is the most intuitive of any I have used so far. The
serial analyzers built into some of the logic analyzers are great
as well.
Douglas
On 2/19/2013 1:09 PM, yoda wrote:
Well I think you are just seeing noise - the CPU pin
should be 4MHz not 50Hz - I assume you are in country with 50 Hz
AC voltages so you are just picking that up. Regarding the
analyzers - I think the Open Workbench Logic Sniffer would be
better - you should download the client and have a look - pretty
simple to use and when you get used to it or need it, it will have
much more capabilities than the Sanalogic and is actually cheaper
from what I can see from the web page.
So it seems if you trust the multimeter then you have no CPU
clock and that will most certainly not work.
On Tuesday, February 19, 2013 2:18:46 PM UTC-6, rbruinsma wrote:
Op dinsdag 19 februari 2013 03:29:08 UTC+1 schreef Sergey het
volgende:
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).
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 :-)
Thanks,
Sergey
Strange things are happening over here ;) when I use the
multimeter with 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
- Sanalogic http://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!
You received this message because you are subscribed to the Google
Groups "N8VEM" group.
To unsubscribe from this group and stop receiving emails from it,
send an email to n8vem+un...@googlegroups.com.
To post to this group, send email to n8...@googlegroups.com.
Visit this group at http://groups.google.com/group/n8vem?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.
|