How to make the insides of a small portable device?

Question

Electronics

This device should only work with one lightweight program. Initially, I wanted to buy a microcomputer, but they have extra connectors that will not be used just like that, taking up space. I have never soldered, so I don’t know what to take as a basis, and also how to attach a display, 4 buttons, a speaker, a headphone jack, a removable microSD to this basis, and so that it all works from a small battery, like in smartphones, with charging from usb-microusb cable.

Answer 1

The display, buttons and microsd can be screwed to arduino (atmega, attiny) or to esp, stm or other microcontroller, depending on the tasks. There are many different microcontrollers, they differ markedly in power consumption, hardware "power" and price, and when choosing, you would need to understand what you generally want to do.
With charging, too, everything is quite simple, you can screw something like such chips
. But with sound, everything is more complicated. If a "tweeter" can be made on any trash, then to reproduce high-quality sound, you will need a good DAC, and perhaps a more powerful processor.
Your best bet is to hire/call someone who is good at electronics design to help. If you are interested in it yourself - look for diagrams of similar devices, go to the electronics forums and start asking your questions.

Answer 2

Maybe it's easier to consider raspberry?

Answer 3

it all depends on your task.
Maybe you need a "microcomputer" (and what is it?)
Maybe an inexpensive tablet is enough for you, which is much cheaper and more convenient and better than a bunch of Raspberry + display and there already is a "display, 4 buttons, speaker, headphone jack, removable microsd"
Maybe you don't need a screen, but you need to solve multiple tasks in real time and manage a complex system, then you need a Raspberry or equivalent. Again, there are a lot of options.
If the task is one and not difficult, maybe an STM32 board or even an Arduino board is enough for you.
Again, it is not clear if your "lightweight program" already exists, then it is written for a specific platform and equipment, and if there is no program, then it is not clear who will create it
The probability of soldering in the case of using STM32 / Arduino is higher than with Raspberry. But you can do without soldering.
Briefly speaking. Describe the task, and there it will be seen