Build your own web-based multimeter using a Pi Pico

Introducing the Electromaker Multimeter W!

Note: We have Raspberry Pi Pico's in stock and can ship worldwide!

Here at Electromaker, we understand the challenges faced by makers, and after putting our best and brightest to the task (Robin, of course), we have come up with the ultimate solution; the Electromaker Multimeter W! 

Powered by a Raspberry Pi Pico W, the multimeter is able to read both current and voltage simultaneously via two independent inputs while making this data available over a web interface. The use of an external circuit allows for the Pico W to read voltages and currents safely with numerous protection circuits, and the use of a current-to-voltage converter allows the Pico W to use an ADC to measure current.

Thanks to the Pico W’s Wi-Fi capabilities, we use the Pico to host a simple website that can be accessed by any device on the local network. This web page displays the current reading of both ADCs with some additional processing so that the correct voltage and current are shown. At the same time, JavaScript that locally runs in-browser make repeated GET requests for new data, and this allows the web page to show live changes in data without needing to refresh.

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▬ Contents of this video ▬▬▬▬▬▬▬▬▬▬

The trouble with multimeters 00:00
Introducing the Electromaker Multimeter W 02:26
How it works, the schematic 04:12
The Raspberry Pi Pico W Code 09.36
The HTML code 12.04
How you can support us! 14:25
PCBs, how he makes it! 14:57
A practical demonstration 16:15
Final thoughts 17:57

[bLaaSsFTW]

What an amazing idea was of using the positive gpio detection, such an ingenious engineer :D Thank You!

[Electromakerio]

We have Raspberry Pi Pico's in stock and can ship worldwide!

[rmfeld]

Great Idea! That analog input circuit is just what I was missing! 
I recently used the Pico to measure and record a rather weak signal and I realised, that the ADC ist quite noisy. In the Picos data sheet is in section 4.3 a hint on how to (in my experience significantly) reduce the noise. You basically can reconfigure the power regulator on the pub to trade off power efficiency for reduced noise levels by driving high GPIO23. It's could reduce the somewhat noisy behaviour that your build showed in the video.

[louco]

Can we use a bigger R1 to avoid loading the circuit under test with only 10K when the voltage goes negative?
Thank you for the video.

[gadoke]

Hi this is a great video especially for us who are just starting to learn new things integrating software and hardware, just want to ask the voltage and current range this project can be used to. Is this for low voltage and current only. If it, is can you make a sequel for higher voltage and current use case. I'm thinking of using this project for monitoring my solar setup and to automate powering up / down some electric devices based on the voltage available on my battery bank.

Thank you and hope to see more of this kind of tutorials from you.

[CPRebels]

What is the max input voltage? Could it be increased with additional output dividers?

[gregMD]

Would love to do this with 6 analog inputs. Is it scaleable?

[dn]

Freqency. Inductor. Capacitor measure possible?

[Konrad_Wallmeier]

Great video. Where can I download the sample code?

[opijkkk]

it will be a good idea monitorin pc voltage

[jyvben]

sadly the demo webpage was way too small too read, that font could have been much larger or the insert bigger !
still interesting.

[nemesis_]

Project is what I want
But your magic RV2 was not explained
Is a manually adjusted potentiometer? If so, should have said that instead.
Otherwise what is a voltage divider “by 10”.
Also I skipped the coding, and saw the demo
The demo had 2 batteries 🔋 🔋 1.6+1.6=3.2 and if they went through a divider /10 the out put should have showed 0.3v, perhaps you code multiplied it back up x10

Would have been more satisfied seeing the demo with voltage beyond the 3.3v max GPIO can handle (such as an automotive 12V 850amp battery)
Because if the RV2 simply passed the voltage (as shown in the demo) with simple batteries nothing is damaged.

I’ll re review the video in entirety and consider building it, thanks

**EDIT... The RV2 could have been shown as (OpAmp output junction with the above R3) connection to
1K ohm >> 9k ohm >> GND, with the GPIO26 connected between the resistors

1 / (1+9) = 1/10th = R1 / (R1 + R2)

For Comment readers, another example: R1 / (R1+R2) = 2.5kohm / (2.5kohm + 10kohm) = 2.5 / 12.5 = 0.2 = 2/10 =1/5 so only 20% of the input voltage would get to GPIO pin

[xaytana]

I've been considering integrating various projects together. This, the HaD oscilloscope, I've seen talks about an experimental LCR using an RP2040, etc. Basically an all-in-one electrical measurement multitool (not just a multimeter) for at least lightweight work with all bases covered within a singular tool, not to mention how compact and portable it could be, and at a fairly low cost assuming it works well enough. The only real downside of the chip is its absolute dogshit ADC, nearly every project that uses analog on a Pico outright requires a better ADC due to how utterly limited and poorly limited the built-in one is. I hope the Foundation's next mcu chip fixes this issue and is overall more usable, as the limited number of input itself is also a bit lackluster.

[byronin]

nice project you can check last video:)