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Reverse engineering the FNIRSI 1014D

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pcprogrammer:
Found the causes of the problems I'm seeing.

1) I forgot about the crappy input design, where they lift the ground level to 1.25V, and when the USB port is connected to the PC which is grounded to the same level as the signal source the signal center drops to -1.25V.  :palm:

2) The power supply setup in the scope with the use of an external switching power supply is so crap that it does not reject it properly and that gives the distorted reading. I tested the scope with the battery pack of one of my 1013D scopes and it cleans the signal right up.

And that explains why the original firmware relies so heavy on the filtering they build in to the software.

This means that the code I have so far is working as intended, but to make use of it a much better power supply is needed for the scope. I have to mention that I'm not using the original power supply, because the scope came with a US style adapter. So can't rule out that the one I'm using is making it worse. Have to try with a couple of other ones I have lying around.

Now it is back to work my way through the to do list I have.

pcprogrammer:
Still slaving away on this. My to do list just refuses to shrink. :-DD

Every time I add something new or think of an improvement I come up with a couple more things to check or change.

For instance the trigger level should be allowed outside the trace window, which on the original is not the case. So I modified that and added arrows to indicate where the trigger level pointer is.

That leads to the horizontal trigger position, which should also be allowed outside the trace window due to the fact that there are most often more samples there. So that's on the list.

At the moment some 32 items on the list that need to be looked at for either implementation or changing.

Attached is a screen capture of my simulator showing the trigger level arrow on the top side of the trace window.

NoNickName:
First post. Kudos to you for the dedication and persistence.
Following the thread.
I have a couple of Ubuntu VMs and also WSL installed, and I have a FNIRSI 1014D for which I volunteer testing.

pcprogrammer:
Another small update.

The to do list is still on 32 items to handle, even though I tackled quite a bit of them.  |O

A first test release will come soon. Need to finish the X-Y mode on correct limits in positions and information, and add a save and restore of the normal mode channel positions.

A bit more work is in the thumbnail part that needs some work for the X-Y mode too, but also fixing the wrongs that arose from the trigger positions outside the visible trace window.

Hope to get that done tomorrow, with which there will be a testable version of the basic scope functionality.

No generator, FFT or roll mode.

pcprogrammer:
Not fully done, but don't have the time to work on it for the rest of today, so no source release just yet, but a version to play with.

Instruction to load it on the SD card can be found earlier in the thread or in the thread about the 1013D or in the repository for the 1013D firmware.

Issues already found by me:

* After closing the item view screen (picture or waveform) there can be yellow lines on the left of the screen.
* Thumbnail pointer positions for XY mode are still missing and the trigger pointers can be in the wrong place when outside of the visible window.
* Not sure how, but the measurement items can be mixed up when going back and forth between the different modes. (XY, item viewing and normal)
If this one is found see if it can be replicated and report on it if so.
* After USB connection is closed the sampling does not start until user input.
Have not checked this on the actual scope.
* Measurements are very volatile and need filtering.
I have not tested this version on the scope with actual signals.

Well have fun playing with it.

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