Unstable range reading

[lass5216]

Hello Community.

I have built an ultrasonic distance measure with an Arduino nano 3.0 (clone) and a Maxbotix sensor.

I just bought a new Arduino nano every (original) to exchange with the old clone. This is to give higher memory and a better input voltage range.

However, I get some unstable readings with the new Arduino Nano every. Everything is wired up the exact same and I have tried with another NEW Arduino nano every - same problem.

I was not expecting the original to perform worse...

Any suggestions on what to look for or any idea why this could be?

Wires:
5V - Voltage input (sensor)
Gnd - Gnd
A0 - 3pin (sensor)
D13 - 4pin (sensor)

All the best,
Lasse.

[Ballscrewbob]

You should bear in mind that the new series of NANO are 3.3 volt so not all sensors will work as anticipated.

Some may even need a seperate power rails with a common ground back to the Arduino board.

[lass5216]

Hello ballscrewbob,

I am pretty sure that this Arduino Nano Every runs on 5V internally and that must be the same reference as the previous one.

I have tried adding a resistor & capacitor but with no luck.

I have also tried using the internal 4.3V as a reference, but the same instability happens. The readings vary between 49-54 cm measuring close focus on a hard surface.

The instability is less running on USB, but it is still there. My plan is to power it with a 16V V lock battery and when doing so, I see a larger instability.

/Lasse

[Ballscrewbob]

A schematic of HOW you are using external power may be useful even if hand drawn.

Stability of power supplies is also pretty important.
Also important is the exact sensor model so people can check the requirements expected.

The more you give EXACT details the better the chance of a good answer.

Could you also take a few moments to Learn How To Use The Forum.

Other general help and troubleshooting advice can be found here.
It will help you get the best out of the forum in the future.

[lass5216]

Thank you,

I have attached a schematic. It is fairly simple.

The reason why I am not questioning the power supply or the sensor is that it is stable with my old Arduino nano 3.0 clone.

The sensor used: Maxbotix MB 7363 HRXL-MaxSonar - WRLS

All the best,

[MarkT]

The Nano Every has an MPM3610 step-down converter module to generate 5V from Vin, I suspect this
is generating a lot of noise on the power rails (there's no room for large bulk decoupling on that PCB...)

I suggest putting 220uF or so directly across the power supply pins of the sensor module so it has much
cleaner power.

[lass5216]

Hi,

Thank you for looking into this. At the moment I only have a 100uF 10V at my disposal, but with no luck. I have tried using this package from maxbotix: MB7961 Power Supply Filter – MaxBotix
I have attached a picture of the readings when using the capacitor. I will try to get a 220 uF, but I guess the 100uF should be able to help a little?

[Wawa]

It seems the serial output has 10 times the resolution. Why not use that.
The Every has an unused TX1/RX1 set.
Leo..