r/raspberrypipico

It look me months to finish this. It's my first Raspberry Pi Pico project.

Features:

- Automatic midi output (aligned with the playback whenever you want it to happen)

- Click output (for drummers IEMs)

- Stereo backing tracks output (for FOA), can output mono from left channel if FOA doesn't have space.

- Dynamically generated click and count-in. The click you hear in the demos isn't an audio track but generated live on the Chrona

- Banks (each bank being a setlist of tracks)

- Fully controllable via two footswitches

- Tempo LED that doubles as an aux button (used to open the menu)

- Expression MIDI support (ramp up and down whatever you want)

- 32GB memory

AI disclosure:

I'm a full stack software engineer and did most of the microcontroller myself, save for asking AI to help me make USB file transfer faster as it kept getting bogged down from RAM use.

PCB and CAD design all my own (from my guitar pedal background)

Desktop app is pretty much vibe coded, directed it feature by feature until I was happy

Hi everyone!

For the last 2 months, I’ve been learning raspberry pi pico, electronics, soldering, CAD software, and more to remake a mechanical drawing toy I found in my drawer:) On the second image you can see the insides of it.

Hardware is really fun, and I enjoyed the process so much. Finally, I got everything working, and it just looks very cool in my opinion.

Also, if you are interested, I made a whole video about the creation process, challenges and how it works.

https://youtu.be/IhqKNODgfBE

Code is available on my github page

I'd love to hear your feedback and what you think about it!

Who know how I can use a rp2040 board to but pwn on iPhone XR. Every infor is appreciated

A while ago, I posted here about getting the first CPU-independent parts of CHARM-II, an RTOS I originally developed in 1986, running on a Raspberry Pi Pico.

Previous post:

The First Original CHARM-II Kernel Code Running on Raspberry Pi Pico
https://www.reddit.com/r/osdev/s/gthHF6vBrl

At that point, there were no timer interrupts or real context switches yet.

Now those parts are working too.

Six tasks are running with independent stacks. An RP2040 hardware timer interrupt calls the CHARM-II tick and scheduling logic, and the actual context switch is done with PendSV on the Cortex-M0+.

I also ported a six-task demo I had previously reconstructed on POSIX. Six tasks move around three tracks, with a critical zone protected by a CHARM-II queue used as a semaphore. On the Pico, the tasks are now actually being preempted by the hardware timer rather than cooperatively yielding.

So technically, this is pretty much the milestone I wanted to reach.

But getting it working gave me another question.

The original targets in the 1980s were processors such as the 68000 and 80186. With the CPU resources available at the time, an RTOS was a useful way to organize multiple concurrent real-time activities.

But what if we had had something with the performance and price of a Raspberry Pi Pico back then?

For many systems I work with today, especially UI-oriented embedded systems, if all the required processing comfortably fits within one frame, a superloop plus interrupts may actually be simpler.

Once everything becomes preemptive, I also have to start thinking about reentrancy, synchronization and shared state in existing libraries. That cost is starting to look more significant to me than it did when I started this experiment.

Yesterday I visited someone who has built a home railway simulator using real railway controls connected to a Windows PC through Pico, ESP32 and Arduino boards. We talked about this, and he said something very simple:

“If one Pico isn't fast enough, add another Pico.”

That hadn't really occurred to me.

In the 1980s, adding another CPU was a fairly serious architectural decision. With today's inexpensive MCUs, distributing the work across two or three processors can be a perfectly ordinary option.

So after spending quite a bit of effort getting a 40-year-old RTOS to perform real preemptive context switching on modern hardware, I'm becoming more interested in a different question:

Where would you draw the line today between an RTOS, a superloop/event-driven design, interrupts, and simply distributing the work across multiple cheap MCUs?

I'm also thinking that when I publish the modernized version of CHARM-II, I may deliberately keep it very small — just enough task scheduling, queues, timer ticks and context switching to run this six-task demo.

Then I can use it as one reference implementation and try implementing the same behavior without an RTOS.

Hey all!

As a fun hobby project, I wanted to see what kind of Unix-like experience could be squeezed out of the RP2040 using bare-metal Rust (no_std) & ARM Assembly.

I ended up building Pico-OS, a tiny dual-core operating system that fits into just ~70 KB:

• Dual-Core SMP: Core 0 runs the shell, Core 1 handles real-time tasks with dynamic load balancing.
• 4-Pane tmux: Virtual split screens (split-v, split-h) directly over USB/UART serial.
• Live htop: CPU% per core, RAM, VFS, Swap, and interactive task manager.
• Storage: In-memory tmpfs + 1.0 MB persistent flash partition with delayed auto-commit to protect flash wear.
• Extras: Full math CAS (calc), nano editor, and a 95% RAM OOM-killer guard.

I'm planning to work on ESP-01 Wi-Fi modem and OLED drivers next.

Would love to hear your feedback, thoughts on the architecture, or any cool ideas you think would be fun to add!

(The project is fully open source on GitHub if anyone is curious: https://github.com/MortalErlik/pico-os )

There are WiFi controlled sprinklers out there, doubtful any open sourced for control. According to Google it is a popular DIY project, so why should they get all the fun.

Most people seem to be using 8 relay boards available on Amazon for under $10. That really is quite deal, but relays are overkill for a sprinkler system running at 24 VAC.

Most consumer units use run of the mill triacs. And you can get opto-isolated versions.

My first design would have attempted to just use the opto-isolated triac, sounds good, but between comments from others and claude reviews real power triacs had to be added. Luckily it all still fit into my proposed PCB layout (and enclosure I picked up). Just had to move the MOC30x2 to the bootom of the PCB along with snubber networks. (schematic and layout in gallery)

So I got the PCBs in, but still had to chose some components. Instead of building 8 channels, I used an old blank PCB and breadboarded up one channel. With that I verified the operation and started tuning the components. Discussions with Google AI and probing with a scope, the zero-cross opto-triacs behaved well and had no overshoot problems. Actually the overshoot for rnadom triacs was less than 20% so lots of headroom on voltage so a snubber was not needed, but the best values would be 4700pF and 47ohms. (jig in the gallery).

So now time to build up the board, where I am now. The 24VAC -> 5V power module will get added when the software testing is done. (box with power module picture in the gallery).

Using the RP2350 W will give me access via wifi and through my tunnel via cell phone so I can control sprinklers while walking around the yard.

I'd like to share a small project I've been working on over the last few weeks.

It's an RFID-based audio player built around a Raspberry Pi Pico clone from AliExpress. I specifically chose that board because I wanted a USB-C connector instead of the standard micro-USB port.

The hardware includes:

- Raspberry Pi Pico

- DFPlayer Mini

- RC522 RFID reader

- SSD1306 OLED display

What's probably even more interesting is that the entire project was developed with the help of ChatGPT. As a beginner, I used it as a programming assistant while designing both the hardware and the software.

One of the features I'm most proud of is a desktop application I wrote for managing the music library. The application scans audio files, extracts metadata such as the title, artist, track length, and folder number, and then automatically generates a "songs.txt" file for the player.

The firmware also includes a built-in menu that allows me to:

- Change the equalizer settings

- Adjust playback settings

- Access a simple diagnostics menu

The diagnostics system checks whether all modules are working correctly and verifies communication with the display, the RFID reader, and the DFPlayer.

Another feature I really like is the RFID management system. New cards can be assigned directly from the device menu. Whenever the player detects an unknown card, it asks whether I want to assign it to a music folder or ignore it.

The project may not be the prettiest one you'll see here, but I'm really happy with how well it works, especially considering my limited programming and electronics experience.

The final version will be battery-powered. I experimented with lithium cells recovered from disposable e-cigarettes, but the enclosure became much thicker than I wanted, so I'm currently redesigning the power system.

There is still a lot of work left to do, but I've learned an incredible amount while building it.

Feedback and suggestions are always welcome. 🙂

Turn Pico 2 W into a USB to Bluetooth Aduio Streaming Dongle; Support AAC; AAC-ELD; LDAC; LHDC-V5

https://github.com/wasdwasd0105/USBPods-Pico2W

I plugged in the usb power and a 18v battery via a buck converter (18v - 3.3v). It was working fine before, but randomly after plugging it in, it stop working. something is fried as it gets really hot with power and obviously, doesn't turn on. every other peripheral runs on the pico's 3v out or gpio. should I have not plugged them in at the same time, usb and vsys?

Recently, I was building a DIY button box on my first-ever PCB. Now, the Pico sometimes works and sometimes doesn't. When it does work, SW9 doesn't work at all. When I plug it in, it doesn't open a folder in Windows like it normally did. It only opens the folder when I upload something to it, and after I upload it, the folder closes. I dont see any phisical damage on the board itself. Did I do something wrong, or is there a way to troubleshoot this?

So I am trying to make a 9 pin DB9 Commodore Joystick to USB converter using a Pico H.

I followed this tutorial here 😄 https://www.instructables.com/Retro-9-Pin-Joystick-to-USB-Converter/

and also this YouTube Vid here 😄 https://www.youtube.com/watch?v=3trAJ24geVI

I managed to get up to the point where you need to basically program the Pico with the supplied code from the website. Then it tells you to modify the code (PicoGamepad) with the new code supplied:

/*

Pico Joystick Converter

Original Code by

by Jake Wilkinson (RealRobots)

https://www.gitlab.com/realrobots/PicoGamepad

Modified by Nick Stevens Feb 2022

*/

#include <PicoGamepad.h>

#define PIN_BTN_0 8

#define PIN_BTN_1 6

#define PIN_BTN_2 7

#define PIN_BTN_3 27

#define PIN_BTN_4 26

PicoGamepad gamepad;

// 16 bit integer for holding input values

int val;

void setup() {

Serial.begin(115200);

pinMode(LED_BUILTIN, OUTPUT);

// Button on pin

pinMode(PIN_BTN_0, INPUT_PULLUP);

pinMode(PIN_BTN_1, INPUT_PULLUP);

pinMode(PIN_BTN_2, INPUT_PULLUP);

pinMode(PIN_BTN_3, INPUT_PULLUP);

pinMode(PIN_BTN_4, INPUT_PULLUP);

}

void loop() {

// Fire Button & flash the LED when pressed

if (!digitalRead(PIN_BTN_0)) {

gamepad.SetButton(0, 1);

digitalWrite(LED_BUILTIN, 1);

} else {

gamepad.SetButton(0, 0);

digitalWrite(LED_BUILTIN, 0);

}

// Left, Right, Up, Down - uncomment these to map to buttons 1 -4

// gamepad.SetButton(1, !digitalRead(PIN_BTN_1));

// gamepad.SetButton(2, !digitalRead(PIN_BTN_2));

// gamepad.SetButton(3, !digitalRead(PIN_BTN_3));

// gamepad.SetButton(4, !digitalRead(PIN_BTN_4));

// Set hat direction, 4 hats available. direction is clockwise 0=N 1=NE 2=E 3=SE 4=S 5=SW 6=W 7=NW 8=CENTER

int hat0_dir = 8;

// Centre the X and Y Axis

gamepad.SetX(0);

gamepad.SetY(0);

//Check where joystick is pointed and set values accordingly

if (!digitalRead(PIN_BTN_1)) {

// North

hat0_dir = 0;

gamepad.SetY(-32767);

gamepad.SetX(0);

}

if (!digitalRead(PIN_BTN_2)) {

// South

hat0_dir = 4;

gamepad.SetY(32767);

gamepad.SetX(0);

}

if (!digitalRead(PIN_BTN_3)) {

// East

hat0_dir = 6;

gamepad.SetX(-32767);

gamepad.SetY(0);

}

if (!digitalRead(PIN_BTN_4)) {

// West

hat0_dir = 2;

gamepad.SetX(32767);

gamepad.SetY(0);

}

if (!digitalRead(PIN_BTN_1) && !digitalRead(PIN_BTN_4)) {

// NE

hat0_dir = 1;

gamepad.SetY(-32767);

gamepad.SetX(32767);

}

if (!digitalRead(PIN_BTN_4) && !digitalRead(PIN_BTN_2)) {

// SE

hat0_dir = 3;

gamepad.SetY(32767);

gamepad.SetX(32767);

}

if (!digitalRead(PIN_BTN_3) && !digitalRead(PIN_BTN_2)) {

// SW

hat0_dir = 5;

gamepad.SetY(32767);

gamepad.SetX(-32767);

}

if (!digitalRead(PIN_BTN_3) && !digitalRead(PIN_BTN_1)) {

// NW

hat0_dir = 7;

gamepad.SetY(-32767);

gamepad.SetX(-32767);

}

//Set HAT direction - uncomment if you want to use the HAT

//gamepad.SetHat(0, hat0_dir);

// Send all inputs via HID

// Nothing is send to your computer until this is called.

gamepad.send_update();

}

I am assuming this means to overwrite the original code with this Pico Joystick Code, which I did. I also included in the Library the PicoGampad.h file, as it seems to need that also?

ok so then it says to write or program the Pico, so it compiles and I get this error:

C:\Users\Rowan\AppData\Local\arduino\sketches\40E539D0694D00283DB7A2A40808C35D\sketch\PicoGamepad.ino.cpp.o: In function `loop':
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:43: undefined reference to `arduino::PicoGamepad::SetButton(int, bool)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:60: undefined reference to `arduino::PicoGamepad::SetX(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:61: undefined reference to `arduino::PicoGamepad::SetY(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:67: undefined reference to `arduino::PicoGamepad::SetY(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:68: undefined reference to `arduino::PicoGamepad::SetX(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:73: undefined reference to `arduino::PicoGamepad::SetY(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:74: undefined reference to `arduino::PicoGamepad::SetX(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:79: undefined reference to `arduino::PicoGamepad::SetX(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:80: undefined reference to `arduino::PicoGamepad::SetY(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:85: undefined reference to `arduino::PicoGamepad::SetX(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:86: undefined reference to `arduino::PicoGamepad::SetY(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:91: undefined reference to `arduino::PicoGamepad::SetY(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:92: undefined reference to `arduino::PicoGamepad::SetX(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:97: undefined reference to `arduino::PicoGamepad::SetY(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:98: undefined reference to `arduino::PicoGamepad::SetX(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:103: undefined reference to `arduino::PicoGamepad::SetY(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:104: undefined reference to `arduino::PicoGamepad::SetX(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:109: undefined reference to `arduino::PicoGamepad::SetY(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:110: undefined reference to `arduino::PicoGamepad::SetX(unsigned short)'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:119: undefined reference to `arduino::PicoGamepad::send_update()'
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:46: undefined reference to `arduino::PicoGamepad::SetButton(int, bool)'
C:\Users\Rowan\AppData\Local\arduino\sketches\40E539D0694D00283DB7A2A40808C35D\sketch\PicoGamepad.ino.cpp.o: In function `__static_initialization_and_destruction_0':
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:20: undefined reference to `arduino::PicoGamepad::PicoGamepad(bool, unsigned short, unsigned short, unsigned short)'
C:\Users\Rowan\AppData\Local\arduino\sketches\40E539D0694D00283DB7A2A40808C35D\sketch\PicoGamepad.ino.cpp.o: In function `_GLOBAL__sub_I_gamepad':
C:\Users\Rowan\Documents\Arduino\libraries\PicoGamepad/PicoGamepad.ino:121: undefined reference to `arduino::PicoGamepad::~PicoGamepad()'
collect2.exe: error: ld returned 1 exit status
exit status 1

Compilation error: exit status 1

I'm in the dark, as I'm not a programmer, and the YouTube tutorial made it look almost plug and play.

Any help would be greatly appreciated

SOLVED, thanks

I have finished phase 1, which is getting the amstrad's printer output as text in the serial monitor, that allowed me to develop the circuit . Circuit is some bi-directional logic level shifters between gpio of the raspberry pi and amstrad's printer port, they don't have to be bi-directional but those were cheaper and easier to replace than resistor voltage dividers and a transistor buffer. Now I'm trying to develop the second phase which is controlling a printer over a USB port using the USB host capabilities of the raspberry pi pico. However I can't get pico to print anything to the printer. I'm trying to solve this issue for the last few days, so if you can help me with the coding part of phase 2 I will be more than willing to share every detail. Also this project is just a start because the same methodology can be implemented to other computers such as commodore 64, Amiga and Atari ST.

Here is the working and tested phase 1 code:

// ==========================================

// Amstrad CPC 7-Bit Parallel Printer Capture

// ==========================================

// --- Pin Definitions ---

const int PIN\_STROBE = 1; // GP1 (Physical Pin 2) - CPC Pin 1 (/STROBE)

const int DATA\_PIN\_START = 2; // GP2 to GP8 (Physical Pins 4-11) - CPC Pins 2-8 (D0-D6)

const int PIN\_BUSY = 9; // GP9 (Physical Pin 12) - CPC Pin 10 or 11 (BUSY)

// --- Circular Buffer (FIFO) ---

// Safely passes bytes from the fast hardware interrupt to the main loop

const int BUFFER\_SIZE = 512;

volatile uint8\_t rx\_buffer\[BUFFER\_SIZE\];

volatile int head = 0;

volatile int tail = 0;

volatile bool character\_received = false;

// --- The Hardware Interrupt (The Data Catcher) ---

// Triggers automatically on the falling edge of STROBE

void strobeTriggered() {

// 1. Instantly pull BUSY high to tell the Amstrad CPC to hold

digitalWrite(PIN\_BUSY, HIGH);

// 2. Read the 7-bit data bus instantly.

// Shift right by 2 so GP2 moves to bit 0, then mask the lower 7 bits (0x7F).

uint8\_t incoming\_char = (gpio\_get\_all() >> DATA\_PIN\_START) & 0x7F;

// 3. Calculate the next buffer position

int next\_head = (head + 1) % BUFFER\_SIZE;

// 4. If buffer isn't full, push the character into the queue

if (next\_head != tail) {

rx\_buffer\[head\] = incoming\_char;

head = next\_head;

character\_received = true;

}

}

void setup() {

// Start Serial Monitor communication at 115200 baud

Serial.begin(115200);

// Wait up to 3 seconds for Serial Monitor to open after reset

unsigned long start\_wait = millis();

while (!Serial && (millis() - start\_wait < 3000));

// Configure the 7 data pins (GP2 through GP8) as inputs

for (int i = DATA\_PIN\_START; i < DATA\_PIN\_START + 7; i++) {

pinMode(i, INPUT);

}

// Configure Handshake pins

pinMode(PIN\_STROBE, INPUT\_PULLUP);

pinMode(PIN\_BUSY, OUTPUT);

digitalWrite(PIN\_BUSY, LOW); // Start in "Ready" state

// Attach the interrupt to trigger on STROBE's falling edge

attachInterrupt(digitalPinToInterrupt(PIN\_STROBE), strobeTriggered, FALLING);

Serial.println("=========================================================");

Serial.println(" Amstrad CPC Printerface, Phase 1 ");

Serial.println(" Circuit Design By Ege Ozpalamutcu & Code by Gemini ");

Serial.println(" Listening on GP1 (STROBE) & GP2-GP8 (DATA) & GP9 (BUSY)");

Serial.println("=========================================================");

}

void loop() {

// 1. Process characters from the circular buffer

while (tail != head) {

// Grab the oldest unread character from the queue

uint8\_t c = rx\_buffer\[tail\];

tail = (tail + 1) % BUFFER\_SIZE;

// Handle standard printable ASCII

if (c >= 32 && c <= 126) {

Serial.write(c);

}

// Handle Carriage Return (CR) and Line Feed (LF) for newlines

else if (c == 13 || c == 10) {

Serial.write(c);

}

// Handle the Escape character (used for printer commands)

else if (c == 27) {

Serial.print("<ESC>");

}

// Print everything else as a hex code for debugging

else {

Serial.print("\[0x");

if (c < 0x10) Serial.print("0"); // Leading zero

Serial.print(c, HEX);

Serial.print("\]");

}

}

// 2. Safely release BUSY only after /STROBE has returned HIGH

if (character\_received) {

// Wait until the CPC finishes its strobe pulse

if (digitalRead(PIN\_STROBE) == HIGH) {

delayMicroseconds(10); // Small settling delay for cable stability

character\_received = false;

digitalWrite(PIN\_BUSY, LOW); // Signal to CPC that we are ready for the next byte

}

}

}

Selling a 7-inch touchscreen display, perfect for Raspberry Pi and DIY/electronics projects.
✅ Fully working touchscreen
✅ Tested and working properly
✅ Compact 7” size
✅ Great for Raspberry Pi projects
I’m selling it because I’ve just finished the project I used it for, so I no longer need it.
Used only one time
💰 Price: 35€
The post will be payed by you.
📍 Albania
📩 DM me for more information.

I’m connecting a 2.4" color TFT display to a Raspberry Pi Pico and I’d like to create a text-based selection interface similar to the one shown in the attached image, using physical buttons to navigate through the options. I’m not looking for a full graphical interface, just a clean menu system with selectable options, navigation, and a way to enter/return from submenus. What would be the best way to implement something like this on a Pico?