Devlog #8 Finishing The project.

What have i done?

• Created a BOM.
• Created a readme.md and made it look good and fit the criteria for submission.
• Compiled all the code libraries into precompiled binaries.
• Created gerbers.
• Rendered good images for the project in fusion 360.
• Added good colors to the design.
• Separated the 3D design printable components into individual printable files.
• Created visual explaining of circuit images.
• Made the first release on github, with all the things you need to make the projects yourself.
• Fixed errors.
• Other things.

Problems i had:

• Forgot to add PCB to BOM.
• Forgot to add Gerbers to BOM.
• Recorded timelapses, but then i accidentally closed the recording tab or my computer shutdown, so i lost the time.

I think that my project is done, i will submit it to the outpost and build it when i get funding.

Devlog #7 Adding holes and mounting holes, battery, pcb changes and adding a hatch and expanding the case

Making holes for micro sd card and micro usb connector:

I have created holes for the micro sd card and micro usb cable.
The micro usb cable is there for when i need to flash code, but dont want to unsolder everything and for when not using battery to test it.
I will mount the micro sd card module with two screws to the case.

Battery:

I always had battery planned in my circuit, but for now i didnt know how big or wich capacity. I chose li-pol. because they fit my size requirements and are small, effiecent. I tried many different sizes and capacities, until i found the one that barely fits in the design (450mah). It should be able to runthe mp3 player for few hours, so that is okay.

PCB changes:

• moved some things to the opposite layers
• moved some things somewhere else, so that it fits in the case
• changed the classic dupont pint for the micro sd card, for a smd spi connector cable, because that is what the micro sd card reader also uses so it uses less space

Case design change:

I had a green pcb still visible with pins and condensators, wich doesnt look good, and can be dangerous. So i covered that part with a hatch and left only the buttons visible.

Things left:

• create bom
• polish the design and the pcb
• check the code for errors
• find the components online
• submit my project

Devlog #6 3D design and PCB

What have i done?

• I have started designing the case for the player in fusion 360.
• I also downloaded all the modules i need and put then in the assembly.
• I exported the pcb and created holes in the case, to fit the components in.
• I created hole for the 3.5mm headphones jack.
• I changed the pcb layout: moved the pico 2 mcu to the back layer, moved many things back.

Problems

• I thought i needed an external amplifier for the headphones, and i changed the design of the case for the amplifier. But then i read somewhere that the pcm module can drive headphones like earphones okay, so i put it back to the original settings.
• I had a micro sd card module that fit in my assembly and i had model for, but then i realized that it is 5v module, so i decided that i change it for 3.3v one, wich is smaller. After some time trying to find the correct model i found one.

Things i need to do:

• Secure the micro sd card to the case
• Add a hole for the micro sd card, so you can plug it in
• Add a hole for the micro usb cable

Devlog #5 PCB

What have i done?

• i have fixed some issues with the code
• added adc voltage divider calculation functio to use my pcb voltage dividers to show me battery voltage.
• added button to the schematic
• routed the pcb

The floating pin problem:

I have made the buttons like i had them in the last few projects, but something didnt seem right, so i googled it and found out i had incorrectly designed the buttons. I had a gnd pin connected through button to the input button pin, but correctly you need to add some positive power through a resistor (10 kiloohms). This problem is called the floating pin problem, if i would have left it that way it would not work correctly and there would be noise and other issues.

Routing the pcb:

I had started routing the pcb. I connected all the things i needed. But i took sime time with the layout of it, like if buttons are down, where is display, and i think i figured it out. I also added the buttons in like a star pattern so they are good to touch. And the battery will be next to the buttons, and most of the sound modules will be down beneath the board. I plan to have 3D printed casing so i added M3 holes to the pcb so i can screw the pcb in later.

Recording problem:

One day i was normally recording but after 40 minutes, i realized that it was not recording and showed errors like reconnecting. I have asked support but nobody replied to me and i tried fixing it myself but it didnt work. I dont know why. On my windows it doesnt work (not even on the desktop application version), but on my ubuntu dual boot it works, but that is problem because i need to use fusion 360 wich is only for windows

What i need to do:

• start designing the 3D model
• download all the additional electronics modules 3D models and make sure they fit in the casing
• check for errors
• add additional features?
• find the components online

Devlog #4 I have coded a lot of new features for the mp3 player and fixed isssues.

Playing issue:

i realized that when playing the audio it doesnt check the buttons so you would not be able to pause it or interact with the player. I fixed it that in loop, it feeds into the sound generator chip only part of the song, then checks for the buttons and repeats.

What does it do now?

-it has 5 buttons for volume control, pausing/playing and playing next or previous track.
-i added an oled display code, so now you can see info about the song, volume etc.
-all the previous features it had.

What do i need to add?

i need to create and design the 3D printed case completly from scratch. I also need to route the pcb.

Devlog #3 I have started writing first code and designing functionality of the mp3 player.

How should it function?

I want the mp3 player to work like this:

1. it reads the files in format of wav or mp3 from the micro sd card.
2. it shows you the info about those songs and you can choose wich one to play.
3. you play the songs, control volume and skip to other.

For the controling of the settings i think i will be using 5 buttons:

• two for volume.
• two for going forward or backwards through your playlist.
• one for pausing and playing the songs.

What did i do today?

• i have connected the modules on the pcb to the correct pins on the pico mcu.
• i have started writing the code and added features like:
  -scanning the names and loading the songs from the micro sd card
  -outputing the song from mp3 or wav format to the sound generating chip
  -checking the buttons using debounce and digital read

What do i want to add?

• firmware to control the oled display, maybe some menu.
• the entire design of the case (i havent started working on it yet).
• finishing the pcb schematic and routing it.
• some other parts like improving the code and features i dont know right now but will add in the future.

Today i added a battery protection circuit, adc voltage dividers and connected most components together. I also searched pico pins diagram on how to connect the pins and i had to change the micro sd card module to a 3.3v one.

I want to make like a portable mp3 player, where you can upload your songs to a micro sd card, and then play them throgh the sound generator to a 3.5mm headphone jack you can listen to. I found the cheao micro sd card reader module to use. I put the pins to it in the kicad schematic, added the main mcu (pico 2 or 1, wich i already have from another project) and added things like oled display ports and simple battery connector, wich i will expand later. I want it to be on lipo battery.