Strange Oscilloscope Reading on Nano

Other Hardware General Electronics
1

Noob here.
I programmed a Nano to produce two digital outputs from 2 inputs.
But my real issues started using my new $180 oscope/signal generator. (ADS1040D)
I was getting signals out of all digital pins.
One of my inputs was analog, and I removed it, and again, signals on all digital pins.
I removed power from the Nano, and still got pulses on all pins.
I tried an unprogrmmed Nano and it was very similar, though some values were different.
The only time the outputs stop, is when I remove the, single digital input.
It seems like I'm hooking up the oscope correctly; an output and an input, and using Auto Run.
Also removing the probes' grounds completely, does not stop the input and output waveforms.
I've double and triple checked for crossed leads etc.
I must be doing something very basic wrong

17127847083321185835386447531103
171278470833211858353864475311031920×1920 415 KB

Can anyone help?

2

Are all your grounds connected to the same point? Each probe must have its ground connected.

3

To test whether the signal is EM pickup from the scope leads, short the scope probe tip to scope ground. Those long loopy connections with alligator clips are great antennas.

Scope probe artifacts are among the worst of beginner problems, and more are in store. Use 10X probes for most day-to-day work, and avoid long wires like the plague.

4

Thanks, didn't think of that.
The voltages were 10-40mV. Ah, I was thinking millivolts, but I think mA is micro volts.
That threw me I think.
I'll check for noise

@ JohnRob
As far as grounds, it's the same if I connect them all or not. I read that they share gound in the scope, at least with generator.
Hmm, but that don't make sense. You could have different circuits. ???
I've checked both ways here on this one.

Thanks for replies.

5

I don't know what happens when you "unprogram it". It's always going to run whatever is in the memory.

How about if you load a program that writes all of the pins high or low and does nothing else.

6

Looking at your picture, I see you are using LED lights. Turn them all off and any fluorescent lights.
I see only ONE possible scope probe. Did you adjust the compensating capacitor as per scope instructions? You are showing two traces on the scope, but only ONE possible 10X probe in the picture. Where is the second 10X probe?

7

With the power off your nano is a block with resistance between each of the pins. With no load you are getting what you should.

8

Also

  • Looks like your channels are set to AC coupling.

  • Suggest you use DC coupling for most controller situations.

  • Suggest you show us better all inclusive wiring connections.

  • Suggest you become a bit neater on you workbench. :pleading_face:

9

Good point. I was just realizing It's too much code at once. + new scope and scoper.
Thanks

10

There's another probe dangling below pic.

I'll look into adjustment. This scope has a different way, and I forgot it altogether.

Will turn off LEDs.
Thanks

11

Thanks. That explains 50% of my confusion.
I appreciate it.

12

Thanks for the input.
I will make above adjustments.

13

  • It appears there might be an issue with split power rails.

  • Make sure you understand the ramifications of breadboard split power rails.

IMG_2734
IMG_27342224×1668 559 KB

14

You busted me on the solder.
I'm going to use a proper gauge wire.
They WERE all on 'blue' with continuity to the nano gnd.
Thanks.

15

IMG_2735

1 Like
16

No power on the Nano?

Where is the power supply connected to the Nano?

17

Wow, yes. Thanks I owe you one.

18

USB[quote="mikedb, post:16, topic:1246285, full:true"]
No power on the Nano?

Where is the power supply connected to the Nano?
[/quote]
Off the laptop USB.

19

Hi guys, so as you remember I had an analog input and a digital input.
The analog input/duty pulse output ran fine.

Then I put code just for digital input/digital output.

I asked it to double the frequency. Tried from 5hz to 30hz. It would not do it.
Put out exactly same frequency as input.
I asked for 4v output to overide noise. It kept the same tiny voltage.

I thought I was on a roll since I had the analog success, but no.
Is the Hz range OK?
Or what could it be?
Seems like the oscope is pretty ironed out.
I tried several codes. Honestly I get them from Controllino. It has made some good codes for me before

20

Hi, @mojave_dean

What are the inputs?
I assume they are from the scope's signal generator.

Can you please post a copy of your circuit, a picture of a hand drawn circuit in jpg, png?
Hand drawn and photographed is perfectly acceptable.
Please include ALL hardware, power supplies, component names and pin labels.

Please include scope connections as well.

Thanks.. Tom.. :grinning: :+1: :coffee: :australia:
PS. What make and model scope? ADS1040D ????