measuring the signal from a circuitry by feeding to the digilent

[Thasni_am]

we are using digilent for giving two types of signal input to the circuitry, so i want to recheck whether the signal is reaching the circuit is working correctly by feeding that to the digilent, so how to feed the signal  from one circuit to digilent and see it in the waveform. how to do it?

 

give me the suggestions or example

[JColvin]

Hi @Thasni_am,

It depends on what hardware you are using.

If you are using something like the ADP3450, https://digilent.com/reference/test-and-measurement/analog-discovery-pro-3x50/start, then you can directly add a waveform generator in the scope view which uses direct internal feedback within the device as of WaveForms beta 3.19.21 (https://forum.digilent.com/topic/8908-waveforms-beta-download) by adding it as a channel in the Scope view. You can either have it display whatever you are outputting in the Wavegen tab (such as the modulated signal I set up) or you can set up a simple wavegen output directly from the scope view.

Otherwise if you are using something like the Analog Discovery 2, no such integrated feedback is available so you would have to externally connect one of the analog input (scope) pins to the to the waveform generator output to view the actual waveform coming out of the device.

Let me know if you have any questions about this.

Thanks,
JColvin

 

[Thasni_am]

@JColvin

Hi, my basic aim is 

from a cicuit(its led circuit, i want to measure how much power/v/current is passing through each led),  i want to take the voltage/ current and i want to see its level like in a oscilloscope how we are seeing, same way i thought i will convert that analog signal using a adc then that converted digital signal i need to pass to digital discovery and want to see that waveform, how to do it ?? is it possible ??

for that i want to know how this adc to digital discovery transfer happening?

 do you have any idea related to it??

if yes can you please tell me how to do it ??is there any link for it similar application??

Is there any other way to check this led current level / power using digital digilent discovery??

 

 

Edited March 24, 2023 by Thasni_am
need to add one more quesion

[Thasni_am]

@JColvin

Hi, my basic aim is 

I HAVE A ADC ADS115, WHICH IS WORKING ON I2C PROTOCOL, HOW TO CONNECT AND SEE  THE DATA IN DIGITAL DIGILENT DISCOVERY? CAN YOU PLEASE TELL ME HOW TO DO IT?/

IF YOU HAVE ANY SAMPLE CODES FOR ENABLING IT PLEASE LET ME KNOW??

 

 

[JColvin]

Hi @Thasni_am,

The Digital Discovery, https://digilent.com/reference/test-and-measurement/digital-discovery/start, does not have an Analog to Digital Converter, so you would not be able to directly measure voltage or current of any kind.

If you wanted to directly measure voltage (presumably to double check what the ADS115 is measuring) with a Digilent device, you would need to use a Test and Measurement device that has analog features like the Analog Discovery Pro 3450 or the Analog Discovery 2.

On a different note, if you were going to use the Digital Discovery to communicate over I2C with the external ADC, you can certainly do this through the I2C tab of the Protocol tool, but as noted earlier you can not directly measure the LEDs voltage or current with the Digital Discovery.

Thanks,
JColvin

[Thasni_am]

@JColvin

Yeah i understood sir, thats why am planning to use ads115 externally then i thought from that output will communicate to digital discovery, using i2c protocol, so how to connect and select the pins, which all parameters i need to set, likein (pattern generator), and do you have any python code samples of how an adc communicate with digital discovery??

that is the part am struggling??

[JColvin]

Hi @Thasni_am,

I don't have any examples for communicating specifically with the ADS115, but WaveForms has some built in I2C examples within the Protocol tab:

You can choose which pins of the Digital Discovery you want the SCL and SDA to be attached to, and then use the built in Read and Write commands to read and write the registers of the ADS115 as dictated by its datasheet.

As for Python examples, there is are a few Digital_I2c scripts available in WaveForms SDK:

Let me know if you have any questions.

Thanks,
JColvin

[Thasni_am]

@JColvin

Hi sir,

thank you for your input, now am working on it., i

1. have one more query(urgent😎),is it possible to control current and voltage of an led (if we given to digital discovery) by using adc, ?? or this controlling is possible with any of the digilent controller?? because i need to program how to   control my led current from digilent digital discovery? if any possible method is there, just let me know

2. i have basic digilent discovery hardware, now i saw higher versions of it digilent digital discovery 2 and all, so basically what is the difference  between higher version, if you have any link just share it? we are planning to buy those things

3. if i have 2 input signal, how to multiply those inputs  signals and getting the new waveform (eg like voltage and current and getting power  wveform)

Edited April 17, 2023 by Thasni_am
need to add one more point

[JColvin]

Hi @Thasni_am,

1. It is effectively (or at least very cumbersome and requires extra external hardware) not possible to control the voltage and current of an LED with the Digital Discovery.
2. The Analog Discovery 2 would be much better suited for your application, based on what you have described. I would not say it is a "higher" version, as opposed to a different product. As for the differences:
   1. The Digital Discovery has 40 digital channels, with a number of the high speed inputs supporting a rate of up to 800 MS/s.
   2. The Analog Discovery 2 only has 16 digital channels, but makes up for the difference with two differential analog inputs (oscilloscope) and two analog outputs (arbitrary waveform generator). The oscilloscope can receive signals between -25 V to +25 V with respect to ground, and the analog outputs can generate signals ranging between -5 V and +5 V. 
      1. Since you tangentially brought it up, the Analog Discovery 2 is not able measure current directly. If you have a resistor of a known value, the WaveForms software (which controls Digilent Test and Measurement devices) can easily calculate the current and plot it alongside the voltage measurement. I'll show how this would be done a bit later in this post.
      2. Similarly, Analog Discovery 2 is not designed to be able to control the amount of current output. The two dedicated power supply channels (+500 mV to +5 V and -500 mV to -5 V) can provide up to 700 mA per channel when an external power supply is used, but the Analog Discovery 2 itself only controls the voltage output; it does not have the ability to adjust the current at a constant voltage or to freely adjust its higher wattage power supply outputs.
      3. If your application instead needs to be able to measure and control current (what you have described so far would not as far as I can tell), I would recommend considering the Discovery USB Programmable Power Supply which has integrated readback on its three variable supplies and can be use in either constant voltage or constant current mode. 
3. The best way to get other calculated signals on the oscilloscope view would to be add a Math channel. Section 3.4 within the Scope section of the integrated Help tab within WaveForms goes into more detail than I will be providing, but by clicking on the "Add Channel" dropdown just above the two oscilloscope channels you can then choose to select a custom Math channel, allowing you type in your own equation to best fit your application. There are also some built in examples for reference, such as the one shown in the screenshot below that calculates the power flowing through a resistor with a value of 100 Ohms by multiplying the voltage measured downstream of the resistor (Channel 2) by the current flowing through the resistor (Channel 1 voltage upstream of the resistor minus the Channel 2 voltage downstream of the resistor, divided by the 100 Ohm resistor value).
   This will create a new channel that will then be shown alongside the analog input channels for easy viewing. The Math channels can also do more complex trignometric calculations as well calculations over an array of values (usually the full buffer of data shown on the display) to enable other types of calculations such as maximum rate of change, integral calculations, and more. Additional Math channels can be subsequently added to perform further calculations on existing channels in case you want to have multiple reference channels.

Let me know if you have any questions.

Thanks,
JColvin