High voltage drop on Nano outputs caused by sketch

[PaulRB]

Here's the signal I see on pin D2 with your original code.

Frequency is around 16KHz, duty cycle around 70%, peak voltage 4.6V, average voltage 4.2~4.3V

Here's signal from D9. Frequency is around 16KHz, duty cycle around 10%, peak voltage 4.6V, average voltage 1.6~1.7V

[machambers]

That's about what I see also.

Thanks again.

[johnerrington]

How to make a schematic you can post.

When you submit a question on the forum you will usually need to add a schematic (circuit diagram). The tutorial that follows will explain some ways to create a useful image; however lets start by explaining how to add the image to your post. Its easy. Having created the image all you need to do is : Save the image somewhere convenient - maybe your desktop Start your post, and place the cursor (insertion point) where you want the image to be shown; [upload image to forum] 3: click th…

You may think the description is enough, but a FULL schematic (EVERY part and how its connected to the "nano" may show factors that havent been considered. Such as supply decoupling or circuit losses.
Are your LEDs all the same type and color? How (physically) are the grounds connected.

skillbank: Experiments and projects with an Arduino microcontroller

what is supplying your 5V?

[TomGeorge]

Hi, @machambers

@machambers

A picture is worth a thousand words.
RPM Footswitch x8 v2 schematic 00c.pdf (15.0 KB)

When everyone can see it.

Tom....

[machambers]

For bench testing it is supplied by the computer USB connection.
In actual use it will be supplied by the DSP processor, a Rane RPM 2m.

[johnerrington]

@johnerrington

Are your LEDs all the same type and color? How (physically) are the grounds connected.

@machambers

With D9 selected, the voltage at the LED side of the resistor is 2.55V.
With D2 selected, the voltage at the LED side of the resistor is 4.03V.

If you measure those voltages with a meter you will be reading the average voltage and as your program is generating PWM signals they arent immediately meaningful.
To test the hardware I'd suggest you run a VERY simple sketch just to turn each on in turn with a useful delay, or read in a number and turn on only that LED.
Different LEDs have different forward voltages, so it would be better to measure the voltage levels at the NANO outputs.

When you reference particular equipment its useful to post a link

rpm2mdat.pdf

[mr_kce_2560]

I have just spent about a week debugging a similar issue using (I think) the same Arduino Nano board as you. Something I came across which did help is the analogReference() function. Check what the default voltage is for your board, it might not be the 5V you expect it to be - it wasn't for me!

There's more info in the arduino documentation about the options for different boards.