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Oscilloscope advice

C

carl0s

Jan 1, 1970
0
Please excuse my electronics ignorance.
I would like to be able to monitor the SCL clock line on a 24cXX I2C eeprom,
so that I can watch for when the eeprom is 'read' by its host unit.
Would any oscilloscope be suitable for this? I am seeing 'digital' and
'analog logic' on eBay. The clock line on these eeproms is only 100Khz or
perhaps 400Khz.
Picoscope looks nice.. but too expensive for this.

thanks for any help

Carl
 
J

Joe McElvenney

Jan 1, 1970
0
Hi,

Please excuse my electronics ignorance.
I would like to be able to monitor the SCL clock line on a 24cXX I2C eeprom,
so that I can watch for when the eeprom is 'read' by its host unit.
Would any oscilloscope be suitable for this? I am seeing 'digital' and
'analog logic' on eBay. The clock line on these eeproms is only 100Khz or
perhaps 400Khz.
Picoscope looks nice.. but too expensive for this.

thanks for any help

Carl

My $0.02 -

The problem with using a scope to do that is how are you going
to relate the 'RD' signal to what is going on elsewhere? You
really need to see some sort of timing diagram (or to trigger on
the occurrence of a unique digital word) and the way to get that
is with a logic analyser. If you should go for one of these on
eBay, make sure it comes with the pods as they are often missing
and as such the vendor cannot have tested it.

Having said all that, a scope would be nice as well for
generally poking about. Nth-hand Tektronix scopes such as the 465,
which won't break the bank, are favourite although there are
plenty of others. There are also surplus Tek 7000 series
mainframes around that take logic analyser plug-ins.


Cheers - Joe
 
W

William P.N. Smith

Jan 1, 1970
0
carl0s said:
I would like to be able to monitor the SCL clock line on a 24cXX I2C eeprom,
so that I can watch for when the eeprom is 'read' by its host unit.

Sounds like you need a logic analyzer more than a scope...
 
C

carl0s

Jan 1, 1970
0
William P.N. Smith said:
Sounds like you need a logic analyzer more than a scope...

Well, I don't want to actually know anything, other than that the chip has
just had its contents read... Just so I can get an idea firstly, that I'm
looking at the correct eeprom, and more importantly, so I can figure out if
there is a time-window within which I need to operate in order to in-circuit
read the chip's contents. I'm using a very basic i2c to parallel-port
adapter (a "non-driven" adapter using just 2x diodes and 2x resistors) with
some neat Russian software to do the reading. It's working fine on what I
suspected to be the correct eeprom, but there's another identical chip which
is not responding.
 
J

Joe McElvenney

Jan 1, 1970
0
Hi,
Well, I don't want to actually know anything, other than that the chip has
just had its contents read... Just so I can get an idea firstly, that I'm
looking at the correct eeprom, and more importantly, so I can figure out if
there is a time-window within which I need to operate in order to in-circuit
read the chip's contents. I'm using a very basic i2c to parallel-port
adapter (a "non-driven" adapter using just 2x diodes and 2x resistors) with
some neat Russian software to do the reading. It's working fine on what I
suspected to be the correct eeprom, but there's another identical chip which
is not responding.

In that case, once the system has settled down, all you would
need is a logic probe with memory. The LED would then come on if
the read line was activated and stay on. Of course, you would have
to have the polarity set correctly but you can get that from the
EPROM data sheet. You could make for one a dollar.

BUFFER -> LATCH -> LED

The schematic for the HP probe and pulser are probably out
there on the web.


Best of luck - Joe
 
P

Pipo

Jan 1, 1970
0
Please excuse my electronics ignorance.
I would like to be able to monitor the SCL clock line on a 24cXX I2C eeprom,
so that I can watch for when the eeprom is 'read' by its host unit.
Would any oscilloscope be suitable for this? I am seeing 'digital' and
'analog logic' on eBay. The clock line on these eeproms is only 100Khz or
perhaps 400Khz.
Picoscope looks nice.. but too expensive for this.

thanks for any help

Carl

Hi, I used my digital storage scope (tektronix) for this. A whole
message can be stored by this. And later you can expand it (10x) and
analyze it on a computer.

You can also use a logic analyzer.

Pieter
 
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