Logic analyzer (HCTEST0006) not working

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DanLuca
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Joined: Mon Apr 16, 2018 10:01 am

Logic analyzer (HCTEST0006) not working

Post by DanLuca » Mon Apr 16, 2018 11:09 am

Hello,

I bought the logic analyzer from Amazon.co.uk, on Saturday.
I successfully installed the driver (WinUSB v6.1.7600.16385, the device is recognized as fx2lafw - generic driver for FX2 based LA), but when I connect the wires to my board, I see only constant signals.

This (evaluation) board contains a uC, on which I'm playing with misc SW. Right now I'm generating square signals (1-10 Hz) on the 2 terminals connected to D0 and D1 channels from PulseView. I can see these signals alternating with a normal oscilloscope, but in PulseView I see only this (see attachement)

It looks that my problem is similar to this one: http://forum.hobbycomponents.com/viewto ... HCTEST0006

Please contact me in order to see what can be done (new/alternative driver installation, device replacement, etc.)

Thanks
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andrew
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Re: Logic analyzer (HCTEST0006) not working

Post by andrew » Mon Apr 16, 2018 2:44 pm

Sorry to hear this....
Please contact me in order to see what can be done (new/alternative driver installation, device replacement, etc.)
If you are looking to return/replace/refund then you can simply contact sales [at] hobbycomponents.com and just reference this post. However if you require help to debug the problem then could I possibly check the following with you:

From your screen shot it looks like the driver has installed correctly and Pulseview is capturing data from the device so I doubt the problem is being cause by a driver issue.

1) I can see that channel D1 is being pulled low. If you disconnect your signal from this channel does this pin go high in Pulseview?

2) If you connect your test pattern to any of the other channels (D2 - D7) are you able to capture it ok?

3) Can you confirm that you have connected a ground wire from your device under test to the analyser.
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DanLuca
Posts: 3
Joined: Mon Apr 16, 2018 10:01 am

Re: Logic analyzer (HCTEST0006) not working

Post by DanLuca » Mon Apr 16, 2018 6:52 pm

Hi Andrew,

And thanks for your reply. I don't want to return the device unless I am sure that it is defective, that's why my first option would be to try a SW solution. Since the device is recognized, I agree that it's unlikely to be a driver issue, so this leaves us with only 2 reasons: defective HW or HW setup issues (in this case, connections with the board)

This being said, here are the answers to your questions:
1. Yes, if I disconnect the wire, the signal goes up in PulseView
2. All other channels have the same behavior (I connected them to the pin where D1 was originally connected, they show '0', and when I disconenct, they show '1')
3. I didn't connect a separate GND wire, I assumed that the USB GND is the same for both ports that I use (1 for HCTEST0006, the other for the eva board). After your reply, I connected both GND pins to the GND on the board, but the result is the same. I will do more tests tomorrow and come back with an update.
4 (additional info): if I connect D1 - D7 to the pin where D0 was originally connected, they all show constant '1'. The difference between the 2 outputs is the frequency: D1 has a freq of 1Hz, D0 has 10Hz.

Meanwhile, are there other things that I can try?

Looking forward for your answer

andrew
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Re: Logic analyzer (HCTEST0006) not working

Post by andrew » Tue Apr 17, 2018 8:46 am

Thanks for the answer. So just to go though what seems to be working..

The fact that Pulseview is seeing the pins toggle (albeit not as expected) suggests that software wise everything is setup correctly.

Your test signals have a very low frequency so the sample rate and sample period shown in your screen capture should be fine. I also assume as they are being generated by a microcontroller they will have an amplitude of ~3.3V or 5V.
I didn't connect a separate GND wire, I assumed that the USB GND is the same for both ports that I use
Yes this is probably the case but for debugging purposes it's probably best to connect a local ground just in case there's something weird going on with ground connections of your PC.

Meanwhile, are there other things that I can try?
Yes, if possible could you try manually connecting and disconnecting D0 or D1 to the GND pin on the analyser whilst doing a capture and see if the in Pulseview the pin(s) toggle as expected. If so can you do the same but instead connect and disconnect D0 or D1 to the GND on your device under test (DUT).

Secondly, if possible can you use your oscilloscope to measure your test patterns whilst they are connected to the analyser. This will help rule out any loading effect cause by the analyser.
Comments made by this poster do not necessarily reflect the views of Hobby Components Ltd.

DanLuca
Posts: 3
Joined: Mon Apr 16, 2018 10:01 am

Re: Logic analyzer (HCTEST0006) not working

Post by DanLuca » Mon Apr 23, 2018 6:28 am

Hi Andrew, sorry for this late reply, it took a while until I got the oscilloscope..., and then I realized it was a false alarm :-(

The problem was caused partially by a different device driver, but also by a wrong HW setup (I misconfigured some jumpers on my board, and the SW signals were routed to other pins than the ones that I intended; I didn't have an oscilloscope to check this until Friday).

I guess a typical configuration issue, and the SW guy blaming the HW or the equipment ...
I sincerely apologize for this, I guess I need to be more careful in the future.

The device works fine

Thanks for your help, and for your patience

Dan

andrew
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Re: Logic analyzer (HCTEST0006) not working

Post by andrew » Mon Apr 23, 2018 3:48 pm

Ok no problem, glad you managed to solve your issue.
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