Products > Test Equipment
RPL1116 (MSO1000Z) and PLA2216 (MSO5000) Active Logic Probe teardown
thmjpr:
--- Quote from: whowe on September 21, 2019, 04:28:32 pm ---Hello thmjpr,
Is Rev2 like a "perfect" version so far?
Really love your USB-C idea. I'm thinking to make one and guess it can bring some fun time with my new MSO5072.
--- End quote ---
Thanks, the ideas are mostly combinations from others in this thread.
I haven't built V2 so I'm not sure, it will still measure only positive trigger voltages, and cable orientation resistors may need tweaking. AngusBeef has ordered boards so he will be the one to try it. Although sounds he will be busy with moving shortly, perhaps after that he will be able to sell the extra PCBs.
--- Quote from: tv84 on September 21, 2019, 05:02:28 pm ---
--- Quote from: thmjpr on June 24, 2019, 01:20:53 am ---BTW there is a SCPI command for LA time offset, :LA:TCALibrate 0.0000002 +/- 200ns but its not working (read back is always 0), suspect in another thread that its not actually been implemented yet.
--- End quote ---
First of all, congratulations for your work! :clap:
Now, my small contribution:
Those SCPI commands are implemented in the FW. I've checked them in the latest FW. (and there are plenty of other functions that are not currently exposed to users, but equally implemented)
Don't know if you are aware of all the MSO5000 SCPI commands that are currently externally exposed? but maybe you have to manually enable "calibration mode". Try these commands:
:CALibration:ENTer
:CALibration:EXIT
I think Rigol has been using this type of protection in the latest equipments so that one doesn't execute unwanted calibrations. My guess...
Edit: These commands are only for the analog channels! |O
Do you do a :LA:ACTive command before the calib to choose the specific digital channel before setting the delay?
--- End quote ---
Thank you, there is a LA threshold calibration as well but I'm not sure why that one doesn't work, it should be reading the voltage internally. Can't recall if we've heard from someone with the official probe if they can confirm. Anyway, it will just cal the trigger threshold voltages, so its not too critical, as they can be read out or manually adjusted if ever needed.
For ":LA:ACTive" command, that is the same as the LA -> Select option on the menu screen. So you can select none, D0, D1, etc. But I tried with either of those and still the LA:TCAL command does not save any offset data. What we want is an entire shift in time from all digital channels to all analog channels.
I could see individual channel adjustment being useful in some niche cases, but IMO its something left to very high end logic analyzers.
AngusBeef:
I got one of the Rev2 logic pods done, I'm short a few caps that'll come on Wednesday so I can finish the other 3.
I will probably finish the rev2 main board tonight or tomorrow and so I *should* be able to test it on Wednesday assuming I track down any shorts or non-connected wires. I did the comparators with a cast iron skillet and my stove :-/O and everything else with a soldering iron so I have run across several components I had to fix up already. I messed up one comparator which hurt my soul a lot.
I already have some boards I screwed up, but assuming all goes well in completing this, I should have 2 main boards and 7 logic pod boards left over. I'll be packing up my place in about 4 days but I'll have them available when I put stuff into storage in another state mid-October and then whatever is left is coming with me to Europe.
I really only started learning electronics about 3 months ago and focusing on it about a month ago, so this is my first 'real' circuit besides breadboarding with an Arduino so I'm just trying to keep my head above water here.
Edit: There could be something worthwhile with the LCSC assembly service seen here - I'm already committed to doing this project but someone else may want to check it out. - https://www.eevblog.com/forum/manufacture/jlcpcb-smt-assembly-service-208764/?topicseen
AngusBeef:
Got two logic pods and the main board done. With just the main board in the scope, I have a lot of noise as mentioned above. But when I plugged my pods in, they light up for a second and then turn back off. I think either I messed up all of my USB connections since I tried the majority of them, or the USB-C cable I have lying around is not a Gen-2 so it may not work correctly. I may get a chance between now and next week to take a peek, otherwise I'll probably get it running by mid-October.
One change I had to make was using an 1uF electrolytic cap for C11 because I must have already packed up my 1uF ceramic caps. I've got it in polarity correct ( :-BROKE) so my assumption was that it will work the same in this situation. Would love to hear some feedback whether or not it's true. From the schematic it looks like the STM32F030F4P6 and all the associated passives are for the OLED screen. Is it possible that they're causing issues if I don't have the screen hooked up yet?
I'll clean up the flux and upload a photo later when I get a chance.
whowe:
I also have made a copy of your Rev2.
I planned to use JLC, but the verification girl insisted it's a "5-board" one and the price was almost 100 USD. I failed to correct her that it was "2 designs only" board. Finally I had to change to another vendor who does not understand impedance part.
Anyway, the board is being shipped to me now. And I also purchased 2 LMH7324 directly from TI (FedEx from Texas) which is expensive but should be genuine.
Hoping for the best result.
thmjpr:
--- Quote from: AngusBeef on September 27, 2019, 12:44:19 am ---Got two logic pods and the main board done. With just the main board in the scope, I have a lot of noise as mentioned above. But when I plugged my pods in, they light up for a second and then turn back off. I think either I messed up all of my USB connections since I tried the majority of them, or the USB-C cable I have lying around is not a Gen-2 so it may not work correctly. I may get a chance between now and next week to take a peek, otherwise I'll probably get it running by mid-October.
One change I had to make was using an 1uF electrolytic cap for C11 because I must have already packed up my 1uF ceramic caps. I've got it in polarity correct ( :-BROKE) so my assumption was that it will work the same in this situation. Would love to hear some feedback whether or not it's true. From the schematic it looks like the STM32F030F4P6 and all the associated passives are for the OLED screen. Is it possible that they're causing issues if I don't have the screen hooked up yet?
I'll clean up the flux and upload a photo later when I get a chance.
--- End quote ---
A random USB-C cable is unlikely to work, as most will not have all wires connected internally (passively). But you can check by plugging it in and beep out the connections if you want. I linked two specific alix vendors earlier in the thread.
Caps won't make a huge difference so should be fine for the moment.
STM32 is purely for the OLED display, if you don't use the display, don't need to populate it or supporting circuitry. It isn't connected to any of the differential signals, and the only connection to Vref0/1 is to monitor those voltages. So just 100 ohm resistors + fuses on the power supply rails would be needed if you want to operate the board passively.
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