Connect Arduino to a speaker with an AUX cable

Hi!
I'm currently working on an arduino project that reads music from an SD card and outputs that music to an aux cord that leads into a speaker with an aux input.
Thats the general idea, but after researching on the web I haven't found a proper tutorial or explanation on how an arduino can output sound via an aux cord.
Can someone help me with that? Thanks in advance.

Goldixan:
after researching on the web I haven't found a proper tutorial or explanation on how an arduino can output sound via an aux cord.

There's a good reason for that: most Arduinos use an 8-bit microcontroller, they were never designed to play music, they lack the necessary hardware.

Either get a dedicated chip/module to play sounds (e.g. DFPlayer), or get a more powerful microcontroller that has more RAM, DMA and an I²S interface or built-in DAC. Most Teensy boards have this, and they can play audio clips from an SD card.

Pieter

I assume you're using the TMRpcm library? And, I'm assuming an Aux input means you have a powered speaker? Add a series capacitor (to block the DC component) and a volume-control pot, and it should "work". (The amplifier may already have both, but if you don't have a schematic you can't be sure about the capacitor.)

But, the Arduino doesn't really put-out PCM (or analog). It puts-out PWM which is a 5V high-frequency signal. That can be "hard" on an amplifier. There is chance of burning-up the amplifier or it may make nasty noises, or just "sound bad", etc. Or, if the amplifier is powerful enough you might fry a tweeter. I would NOT connect it to my stereo system or anything that I really care about... You can filter the PWM to get analog (at least in theory) but I don't think a simple RC filter will help that much.