I'm having trouble with an EEPROM and an LCD module hooked to an AT91SAM7S256. Software is using the at91lib TWI_* routines that came with an evaluation kit. The program seems to be hanging up on incomplete I/O with the LCD module, but I don't know why. Analyzing the TWI (aka I2C) protocol would either nail the problem or assure me that there was nothing to see there.
Where could I get the use of an analyzer?
Thanks, Mel.
I've used
Regards, Steve
If you've got a 2 channel scope that allows you to get CSV files out, then a little bit of quick code can decode I2C prety easily. Otherwise I've been pretty pleased with the Intronix LA1034 at
I do, in fact have one of those USB pods - DSO-2250 -- that does that. I've never used the feature yet, might have been the last thing I thought of.
Saelig has a ByteMaster LAD-16128U, 16 channel -- about half the capability for about 3/4 the price. I like the looks, but shipping becomes a major part of the cost, esp. once the border-crossing charge gets tacked on.
Many Thanks, Mel.
Their web page is a learning curve all by itself. Thanks. I'll follow that up.
Mel.
Consider also the DigiView DV1-100
Oliver
Firstly, you didn't say which LCD module and EEPROM. Doing so might have got a wider response already.
Secondly, Logic Analysers are expensive to own and hire so doing the job without is really a very worthwhile skill that more should learn to cultivate.
If these are serial devices I would expect to see the traces on a scope easily enough. Have you got one that can capture a segment of data from pre- trigger point to post-trigger point (Fluke and Tektronix both do a suitable type). Such a scope will allow you to scroll back through the problem zone to see what was happening in detail.
Also learn to instrument the code (toggle a pin with the idle task or something) so that you can pick up points of failure.
I've been looking for a good oscilloscope front end for a PC, but I haven't found anything I think is worth the price. There are a few units that can do both scope and logic analyzer which would be ideal for me, two channels of analog and 16 to 32 channels of digital. Can anyone recommend something in this line?
Rick
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On the basis that you'll almost definately need it again, renting is a bad investment and just dead money. You could buy a good used la on ebay for a fraction of what it would cost you to rent for a month, or even from a dealer.
Depending on speed requiremnts, an HP 16xx series might be enough, or better still, one of the system type HP16500 or 16700 series. The latter were 25 to 50k $ new and more or less last forever...
regards,
Chris
Yikes, buy, don't rent. We have a DigiView from Tech-Tools that we love. $500 at
This is phenominal logic analyzer. Does data interpretation and lots more.
e.
ore.
I don't have this unit myself, but one of my customers uses it and has more than one.
It seemed to work pretty well to me. $389
Rick
That's my normal LA, also. Lives in the laptop bag so it's always handy.
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love.
s more.
I only wish they had drivers for Linux. I'm not using Linux now, but I don't want to invest in more things that will make a switch hard.
Rick
You could also get n I2C Monitor. MCC-US.com Or
I hate to damn a manufacturer with problems that are probably my own -- see below.
Funny you should say that. After my subconscious got serious about the problem, and I posted my request, I woke up in the night realizing that I was clocking the TWI interface too quickly for the LCD. This seems to be have been true, and bringing the baud rate down to 100KHz has made the board beautifully stable.
The thing I have is a USB scope pod. It would be worth a try to drag the trigger point way over to the right and see if that left me with the last available traces. Since the problem involved intermittently locking up the U.I. loop, and ceasing to send or receive anything from the module, that ought to leave the smoking gun traces in plain view.
Alas, the hardware people didn't leave me any test points. Running that test would have me playing drums and pressing front-panel buttons with several hands while holding a scope probe point on an MCU pin with another. Life is never easy.
Mel.
I am sure no-one would have seen it as damning a manufacturer and one could always add the phrase "probably my own stupidity..." within the mention.
So you have a visions of a solution then?
I suppose I am spoilt in that respect as I either select, build or specify exactly what hardware and software will be put into the systems. I love having suitable test points to monitor what is going on.
Life can get a bit easier with some micro test clips, frees up at least one hand. I have some from pomona that claim to be usable down to 0.3mm pitch ICs. I have used those without problems on 0.5mm pitch, no experience with
0.3mm. One drawback, they ar not cheap but it saves you soldering test wires to your micro which takes a lot of time and has a hazard of damaging things.Have something to add? Share your thoughts — no account required.
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