Hi everyone, I built a synth first out of breakout boards - either an Arduino Nano or a A-Star 328PB Micro into a PAM8302 breakout into speakers or a headphone jack breakout board. When that prototype worked, I moved on to create the PCB around an Atmega328pb, capsense keys, and an on-board PAM8302…

As my crystal ball is out of order today, would be better if you put the schematic with all the details of the PCB, specially how do you power it. And the specs of all the parts, like the speakers.

Hi, @chiptune Welcome to the forum. [image] How to get the best out of this forum IDE 1.x See also FAQ - Arduino Forum for general rules on forum behavior and etiquette. Hello, Welcome to the Arduino Forum. This guide explains how to get the best out of this forum. Pl…

Thank you both! Here is the full schematic and the PCB section I suspect is causing issues, showing the decoupling capacitors on the MCU and the crystal. The crystal is 20MHz because the Atmega328pb supports that - the UNO and Nano are on the older Atmega328p. I can run off of 2x CR2032 but the vo…

It's not surprising the voltage drops. 5V / 8-Ohms = 625mA. (You may not be putting 5V into the speaker, but I wouldn't expect much audio power out of those batteries.)

Exactly. I accepted that the batteries can only run things with an externally powered speaker. Every scenario works with an externally powered speaker. The problem now is the crashes on USB power with an unpowered speaker at >= 20% of the volume (and on the 20Mhz crystal).

As you havent provided deatils of the load you are attaching - speaker or hedphones - I cna only guess; however as has been said if the load impedance is 8 ohm you should not expect to drive it directly - thats why you have added an amplifier. [image] chiptune: I wanted to add, I have 100nF and…

Apologies. The on-board speaker is 8 Ohm 1 W, same issue plugging in headphones. I did not. Is this the best practice? What is the process? I went by the the capacitors that I have on the breakout setup, except I missed the 4.7uF capacitor. Is it critical? I should mention, I am a software person,…

[image] chiptune: The problem now is the crashes on USB power with an unpowered speaker at >= 20% of the volume (and on the 20Mhz crystal). Are the batteries removed when you try this?

Yes they are. It'd have been very silly of me if I missed that :slight_smile:

What is the part number of the crystal you are using?

Synth WIP: Atmega328pb crashes outputting PWM signal into unpowered speaker

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TomGeorge July 15, 2024, 5:35pm 3

Hi, @chiptune
Welcome to the forum.

Can you please post your PCB overlay?
Can you please post a schematic?
Why 20MHz crystal when the UNO is 16MHz.

Thanks.. Tom..

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Synth WIP: Atmega328pb crashes outputting PWM signal into unpowered speaker

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