How wiring: Load Cell ---> AD620(amp) ---> ADS1115(amp + analog to digital converter) ---> Arduino Leonardo

Projects General Guidance
1

Hi,

This is my first post, and I'm a beginner with Arduino. I think what I want to do is possible, but the question is how.

i need help with this:

I'm making some pedals for sim racing, but I have doubts about how to wire the pedal and then program the brake pedal. I want it to work with a Loaded Cell.

I've managed to get the following configuration working:

Loaded Cell --> AD1115 --> Arduino Leonardo
But the signal is very weak, resulting in a loss of resolution, or so I think.

What I want to do is the following:
Loaded Cell --> AD620 (amp) --> ADS1115 (analog-to-digital converter) --> Arduino Leonardo

(1) Loaded Cell --> AD620: To amplify the Loaded Cell's signal up to 5V, because the signal from the Loaded Cell is very weak and difficult for an Analog-to-Digital converter to read.

(2) AD620 --> AD1115: Which would be responsible for transforming the signal it receives from the AD620 into a digital signal.

(3) AD1115 --> Arduino Leonardo: Which receives the digital signal and uses it to display the Loaded Cell's reactions on a Windows game controller.

That's the idea, but the wiring isn't "linear," and I'm not sure how to do it... Does anyone know how to do it, or where I can find information?

Thanks

2

Simplify your life and use an HX711 loadcell amplifier, They are cheap, you can buy them almost anywhere and are more accurate than what you are now trying to do now

3

Yes, and it has higher resolution... in fact, it's a test I did before the ADS 1115... but it's slow to respond, there's a lot of lag. I can notice that from the moment I press the pedal until the game controller in Windows detects it, there's a delay.

4

One option that would be ideal... would be an alternative to the HX711, but faster in reaction.

Is there something like that?

5

There will be a delay with any amplifier/ADC. It's probably your software that is causing the delay.
The HX711 can to 80 samples/second.
How fast do you need?

6

Please, give a link to your load cell to see how much signal it gives on full load under known excitation.

7

This is the link to aliexpress

https://es.aliexpress.com/item/1005004517640674.html?spm=a2g0o.order_list.order_list_main.97.5257194dj2NXCB&gatewayAdapt=glo2esp#nav-specification

its the 120 kg model

In a label in loaded cell, can you read:

Model: CZL601

Rated Load: 120 kg

Precision: 0.2

8

You can use the AD620 and the ADS1115 but the 1115 is only 16 bits and the AD620 does requires a +/- supply.

9

I suppose that with 16 bits (65,536?), I'll have enough resolution for a brake pedal; I don't think it'll be that precise. I'd rather lose resolution and gain response speed...

10

Why did you select 120kg?
The lower the max weight, the more sensitive it will be.

Are you making your own PCB?

11

I didn't know that; it was the model they recommended when I ordered the components to manufacture the pedals. It was in the pedals' Bill of Materials: a 100/120 kg load cell.

No, I'm not making my own PCB...

Gemini proposal
Gemini proposal1920×1047 291 KB

Gemini gave me this wiring... but I don't really trust it, I think I see some "weird" things.

12

Do you know the sensitivity (mV/V of excitation) of your load cell?

13

Is this?

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14

Does your AD620 board look like this

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15

yes, this is

photo

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16

To get started you will need a 9V power supply and a voltmeter to make measurements.
You may be able to use a 9V battery but I'm not sure how long it will last.

17

I failed; I thought the amplifier could work with 5V.

bufff…. think i must change amplifier… some other model?

18

It can but you will only get maybe 3V maximum signal output. That may be OK with the ADS1115, have to check.

19

But if at any point the AD620 allows more than 5V to pass through, I could damage the Arduino, right?

20

No because what connects to the Arduino will be the outpot of the ADS1115 and that is an I2C signal.

So it can be done with the AD620 and the ADS115 if you hook them up right and adjust the AD620 gain and offset correctly.

Do you have a voltmeter?
Have you installed a library for the ADS1115?

For your reference

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