Considering purchasing a Logic Analyzer

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

OMG! I'm so excited! I got the 500MHz bandwidth 2 Gigasamples / second two channel digitizing storage oscilloscope module! Ebay wanted anywhere from 500$ to 1000$ for them but this guy was selling one as is because he couldn't get the triggering to work on it. He said all he did to test was hook it up to his signal generator. I've already downloaded the service manual for it but I'm hoping it's going to be some as simple as it just needs calibrating! I see in the user manual, there's a calibration routine for the triggering stuff. He wanted 150$ + 20$ shipping, I offered 75$, he counter offered 115$, I took it and went for the faster but cheaper shipping (USPS was cheaper and faster than UPS ground) and I paid a total of around 127$ for it!!!!

[Agent24]

Re: Considering purchasing a Logic Analyzer

Sounds good, if you can get it going.

For the record, I bought a $20 USB one (LCSoft Devboard\knockoff) and built my own input protection board. I use the Sigrok\Pulseview software in Linux. It doesn't always work perfectly, but it has been quite useful so far. I would like to get something better one day but for the price they are surprisingly good value.

[stj]

Re: Considering purchasing a Logic Analyzer

For the record, I bought a $20 USB one (LCSoft Devboard\knockoff) and built my own input protection board.

that's the same basic hardware as the one i linked for under $10
i got one expecting to have to change the buffer chip only to find the chinese had already updated the board!

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

Sounds good, if you can get it going.

For the record, I bought a $20 USB one (LCSoft Devboard\knockoff) and built my own input protection board. I use the Sigrok\Pulseview software in Linux. It doesn't always work perfectly, but it has been quite useful so far. I would like to get something better one day but for the price they are surprisingly good value.

Are you using the latest version of Sigrok from their github repository? How stable is it? I've been planning on using the libserialport library that Sigrok uses and develops (I believe) to control my Weller WHP3000 preheater. I wanted to release the code open-source on github for other people but I didn't want to have to write separate code for Windows and for Linux. libserialport seems extremely portable and does all the hard work for me.

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

I think I'm going to be happy with my 16702B when it comes. I was thinking of replacing the 18GB SCSI2 drive with one of those SCSI2SD adapters. They plug into a 50-pin SCSI port and can emulate SCSI 1 or 2 from what I've read and you just use a MicroSD card. They support SDSC, SDHC, and SDXC. The price is a little steep compared to something like a 146GB SCSI Ultra 320 drive but I'd still need an adapter for that to work in this. If the hard drive is bad, I'll probably by the SCSI2SD adapter. If it's good, I'll probably wait a few months before making the upgrade.

[Agent24]

Re: Considering purchasing a Logic Analyzer

Are you using the latest version of Sigrok from their github repository? How stable is it? I've been planning on using the libserialport library that Sigrok uses and develops (I believe) to control my Weller WHP3000 preheater. I wanted to release the code open-source on github for other people but I didn't want to have to write separate code for Windows and for Linux. libserialport seems extremely portable and does all the hard work for me.

At the time, I used the latest one downloaded from the latest ubuntu repos (which was for a higher version than 12.04 I am running on the machine I use for electronics stuff). At that time it was the same version as the one on their official download page IIRC. I don't know if it would be latest version now. I haven't needed to use it for a while.

Mostly it worked fine, but sometimes it would stop capturing prematurely. This happened in pulseview and sigrok. I suspect the hardware. I think I found a post about it online saying the same thing. I can try to find it again if you want to know the exact problem.

But aside from that issue, everything seemed OK for what I did. I never used protocol decoding so far because I so far have not needed to. But from the demo capture files included it does seem to work.

Good thing about it being open source, I expect it would be quite easy to implement new decoders.

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

At the time, I used the latest one downloaded from the latest ubuntu repos (which was for a higher version than 12.04 I am running on the machine I use for electronics stuff). At that time it was the same version as the one on their official download page IIRC. I don't know if it would be latest version now. I haven't needed to use it for a while.

Mostly it worked fine, but sometimes it would stop capturing prematurely. This happened in pulseview and sigrok. I suspect the hardware. I think I found a post about it online saying the same thing. I can try to find it again if you want to know the exact problem.

But aside from that issue, everything seemed OK for what I did. I never used protocol decoding so far because I so far have not needed to. But from the demo capture files included it does seem to work.

Good thing about it being open source, I expect it would be quite easy to implement new decoders.

It's okay about the exact problem, you don't have to look for it. I know they're actively developing it. I had to ask a few questions about the source code and signed up to the mailing list. I just never unsubscribed. It's almost every day now I get a few e-mails with changes to the code. I was under the impression that maybe using the latest from the repository would be a better idea than the version on their site simply because of how knew the code is. I believe there were a lot of changes made upstream (on the github page) that would fix a lot of problems. Thanks for the feedback! Much appreciated!

[japlytic]

Re: Considering purchasing a Logic Analyzer

I think I'm going to be happy with my 16702B when it comes. I was thinking of replacing the 18GB SCSI2 drive with one of those SCSI2SD adapters. They plug into a 50-pin SCSI port and can emulate SCSI 1 or 2 from what I've read and you just use a MicroSD card. They support SDSC, SDHC, and SDXC. The price is a little steep compared to something like a 146GB SCSI Ultra 320 drive but I'd still need an adapter for that to work in this. If the hard drive is bad, I'll probably by the SCSI2SD adapter. If it's good, I'll probably wait a few months before making the upgrade.

In case you didn't know, there are SCSI2CF (SCSI to CompactFlash) adaptors on the market as well.

[stj]

Re: Considering purchasing a Logic Analyzer

very expensive last time i looked at scsi2ata adapters, i would just fit a 36gig scsi drive in it.

[keeney123]

Re: Considering purchasing a Logic Analyzer

You should have plenty fun working with that. People may not see you for days.

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

very expensive last time i looked at scsi2ata adapters, i would just fit a 36gig scsi drive in it.

The SCSI2SD adapter isn't that bad. With shipping, around 69$ http://www.ebay.com/itm/SCSI2SD-3-5-...AAAOSwFnFWBHDt

I couldn't find one that didn't come with the MicroSD card. I'd probably just use one of ours. We have up to 64GB. That should be more than enough, but maybe I'll just take it up to 128GB. I worry that the MicroSD card might ware out a lot quicker than a SCSI2 drive would...

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

You should have plenty fun working with that. People may not see you for days.

Yeah So, I've been trying to get this dang oscilloscope module I bought broken, fixed, to use with my logic analyzer. I contacted China and they found a bunch of the ICs I were looking for. People over on EEVBlog say it's some sort of Logic Array / Gate Array / ASIC and they're programmed during manufacturing and there's no way to program them in the field. So we're hoping the ones China sent me are programmed properly, you know, for this oscilloscope module.

I guess they're kind of like PICs were the pinouts can change. But only when they're making them or something.


Here's a problem I got though. On the back, there's two missing SMD caps. They're 10nF SMD ones that blew off / exploded I think. The IC that I was talking about, it had a screw on the pins and I think that shorted stuff out and made those caps explode. I don't know what voltage SMD caps I should get though. I don't know what type of SMD caps I should get either. I was thinking if they exploded from being shorted out, maybe they're those MLCC SMD caps? I was also thinking maybe I could just order some 15V 10nF MLCC SMD caps and see what happens. From the datasheet, I didn't see any voltages over 5V. The datasheet was just giving a very brief overview of what the chips do though.


Any suggestions?

[keeney123]

Re: Considering purchasing a Logic Analyzer

So what was the 10 nF connected to a crystal? I would imagine the type of cap would be determined where it was used. The only reason you can not program a gate array in the field would be because they do not want you to know how it is program. The gate array as I remember is full of NAND logic they can be programmed burnt in the field to configure almost any Boolean logic circuit.

[stj]

Re: Considering purchasing a Logic Analyzer

crystals use caps in the pF range

[keeney123]

Re: Considering purchasing a Logic Analyzer

Sorry Stj I will make that 10 nF into 10,000 pF

[stj]

Re: Considering purchasing a Logic Analyzer

very funny.
then i will also rephrase.
crystals use caps in the 5-30pF range

[keeney123]

Re: Considering purchasing a Logic Analyzer

Thought you might like that one. Thanks for the info. I could not remember the values. From old school we made oscillators out of discrete components back in the 70's. First crystal I came in contact with was around 1982.

[stj]

Re: Considering purchasing a Logic Analyzer

yea, 7404, crystal, 2 caps, maybe a resistor.
classic clock circuit.

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

So what was the 10 nF connected to a crystal? I would imagine the type of cap would be determined where it was used. The only reason you can not program a gate array in the field would be because they do not want you to know how it is program. The gate array as I remember is full of NAND logic they can be programmed burnt in the field to configure almost any Boolean logic circuit.

Thanks for the response Keeney123. So, do you think just replacing this IC won't be enough? It'll need to be programmed? Or do you think there's a good chance that it's actually programmed? Someone, I think STJ, said they thought the part number was more or less an internal part number used by Agilent / HP. To me, that means if I find the same chip with the same part number, there's a good chance it's been programmed the same way or it's simply not programmed at all.


As for what it's actually connected to, I'm not sure, besides the gate array. The Logic / Gate Array had a broken screw grounding out terminals. I can't find schematics for the oscilloscope module. Physically looking at it, it looks like both of the caps just connect to different pins on the IC, through vias. I can't see many traces. I think maybe there's more than just two layers. I could use a DMM and try figuring out where the vias go to if it'd make a difference, like what pin number, etc.

[keeney123]

Re: Considering purchasing a Logic Analyzer

I was just saying that a gate array can be programmed in the field. If HP was responsible for making this machine you might what to call them to make sure the IC is programmed. Also, if this O-scope is an older model you might also be able to get the schematics from them. The schematic would be useful if there has been more taken out then one chip. I fact the chip may not be damage, you might of taken out a power supply circuit. It would depend on actually what was shorted and how it is connected in the circuit. The schematic would also be useful if you need to repair this thing in the future. If they are unwilling to give you the schematics there must be some company that either sells them of you can get for nothing.