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john g

Issues sending/reading waveforms using discovery 2

Question

Hello,

I just purchased a Discovery 2 board and am trying to familiarize myself with it and WaveForms (win 10). When I plug the board's waveform generator (pins 1+ and 1-) into the board's scope (pins W1 and GND) and deliver a sin wave, I can view it in WaveForms. However, when I plug the Discovery waveform generator into my Tektronix oscilloscope, I cannot detect any waveform. Similarly, when I plug my Tektronix waveform generator into the Discovery 2 scope and apply a sinusoid, the Discovery 2 cannot measure any waveform. Does anyone know why the discovery 2 board is able to generate/read its own waveform, but it can neither generate/read a waveform that can be detected by other instruments? I have included an image of my wavegen and scope setup windows within WaveForms (when the Discovery 2 waveform generator and scope are connected).

Thanks for any suggestions!

-John

WaveFormsExample.PNG

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Hi @john g

If you have connected as it is in the drawing it is wrong.
According the wire colors in the waveGen_DPO you have connected AD2 Scope to Tek Scope and in AFG_Scope looks like you have connected AD2 WaveGen to Tek AFG

When connecting AD2 Scope to AFG you should have 3 connections:
- AD2 GND (black) to AFG GND, this is a must, the scope inputs are differential but not floating
- AD2 1- (orange/white) to GND, this is important specially for high frequency signals
- AD2 1+ (orange) to AFG output
When connecting AD2 WaveGen to Scope:
- AD2 GND (black) to DPO GND
- AD2 W1 (yellow) to DPO input

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Hi @john g

Make sure you have ground connection between the devices and circuits!
Without such the readings/measurements likely to be wrong or the devices/circuits can be damaged 

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Hi Attila,

Thanks for the response. I have connected the grounds between the Discovery 2 and my other devices, but find the same result.

-John

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Hi @john g

Could you post photo with the wiring between the devices?
It would be also good to see the Tektronix scope and awg configuration? scope time base, range, input coupling, generated frequency, amplitude...
Can you see the signal generated between the Tektronix devices?

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Hi Attila,

I cannot provide photographs, but I drew schematics for each of the setups that I have tried and screen shots of the results. To help clarify, I will refer to the Discovery's waveform generator as "WaveGen", Discovery's scope as "Scope", the Tektronix function generator as "AFG", and the Tektronix scope as "DPO". I used the following parameters:

WaveGen: freq = 10 kHz, amp = 1 V

AFG: freq = 5 kHz, amp = 1 V

DPO: time base = 100 us/div, range = +/- 4 V, coupling = 1 MOhm, 11.5 pF

AFG_DPO.tif AFG_Scope.tif WaveGen_Scope.tif waveGen_DPO.tif

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Hi Attila,

This is a very silly mistake. I am not sure how I misread those wires. Thanks for your help!

-John

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