SamplerBox is an electronic musical instrument. Drop audio samples onto it, hook up a MIDI keyboard, and you'll be able to play with realistic piano, organ, drums, etc. sounds!

The Samplerbox is a small device that plays pre-recorded instrumental sounds when it receives MIDI commands. Vintage products that do this include: ASR-10/EPS/Mirage samplers. Here are other similar products: Sound Modules

It's sample player. It's a MIDI sound module. It is a ROMpler. It stores the sounds of instruments and plays notes from those instruments when it receives MIDI note commands. Those sounds can be any WAV files. You can freely download sound files (samples and sample-sets) over the Internet, or you can record them yourself and copy the sound files into SampleBox. It can then receive MIDI from a MIDI keyboard controller, or any other MIDI device and play the sounds out an ordinary line-out jack.

The original Samplerbox project is described at this website:. https://www.samplerbox.org/ However that's outdated now. We're providing current (May 2023), much easier build instructions at http://chromakinetics.com/samplerbox/. 

Extensive, detailed information on the latest Samplerbox development is at: https://homspace.nl/samplerbox/ Note: this website may be offline. Use the Wayback Machine to view the archived version of that website if necessary. There are a whole lot of pro-level features documented there that you can access, depending on how much complexity you want to deal with.

Good article on using a Samplerbox as a Mellotron replacement SamplerboxMellotronArticle.pdf

Full build instructions are at http://chromakinetics.com/samplerbox/

Required Parts

1. Raspberry Pi 3B+ $35 or Raspberry Pi 4 (any memory size) (also should work on a Pi Zero 2, but these directions do not cover that model.
2. Pimoroni Pirate Audio LineOut $25 Pimoroni website
3. Power supply for Raspberry Pi (5V 2.5A with correct connector for the Pi model)
4. MicroSD card at least 2GB (I'm using 16GB)
5. a microSD card reader or microSD adapter (if your computer has a full-size SDcard slot built-in)
6. a MIDI keyboard (either a USB keyboard or a 5-Pin DIN MIDI keyboard connected to a USB MIDI adapter)

MIDI SysEx Patch Loader / MIDI snippet player

MidiCommander is a CircuitPython app running on a PyGamer with a MIDI Featherwing plugged in and with an SDcard. It enables a user to "play" syx and .mic files containing snippets of MIDI commands, stored in folders of "playlists" on the SDcard, out to connected MIDI devices. It may be used to send MIDI data to several devices to configure a MIDI setup for each song during a gig.

• Files containing MIDI command bytes are to be stored on the SDcard in the /syx folder and its subfolders. The joystick UI enables navigation to subfolders.
• Filenames and folder names that start with a period are ignored.
• Only files with a .syx or .mic extension are seen by this program
• You can put any MIDI command bytes into a .mic or .syx file and this will send whatever is in the file, so you can send Program Change, CC and other - you are not limited to SYSEX commands. You can put all the MIDI commands needed to configure your rig for a song in one file.
• Arrange the files in a folder in the order of your setlist and then during a gig, simply choose the file and press a button to send it -- and all your MIDI instruments are configured for the song.
• Press the B button for Help

Full details on this website: http://chromakinetics.com/midicommander/

Open source CircuitPython & Python on Github at https://github.com/gmeader/pybadge/tree/master/MidiCommander

This is a derivative work of the original SysEx “Librarian” by: kevin@diyelectromusic
https://diyelectromusic.wordpress.com/2022/05/28/raspberry-pi-pico-sysex-librarian/

Modified for Adafruit PyGamer with MIDI Featherwing by Glenn Meader 

You can get the required hardware: a PyGamer and a MIDI Featherwing for about $50 at adafruit.com The MIDI Featherwing plugs into the back of the PyGamer to provide DIN-5 MIDI jacks.

With the new Raspberry Pi 5 coming out, it is time to add support to Blinka, our CircuitPython library compatibility layer. One of the biggest changes to the Raspberry Pi 5 is the addition of a new southbridge chip, called the RP1, which now handles the GPIOs. Like many other projects, we have been the RPi.GPIO library to handle the General Purpose Input/Outputs. The only issue is that RPi.GPIO does not work on the Raspberry Pi 5 due to a changed memory mapping. Whereas everything was handled by the /dev/gpiomem device before, now everything is dynamically split into multiple gpiomem devices. The 40-pin GPIO header happens to fall into /dev/gpiomem4.

So this means it's time to look at a couple of new options that do work on the Raspberry Pi 5. The two biggest contenders are libgpiod and gpiozero, though there does appear to be a pure python version of libgpiod called gpiod. RPi.GPIO was written in c, so it should run faster than a pure python implementation, however as mentioned before, that no longer appears to be an option. So the replacement should be able to run as fast as possible.

On the surface, libgpiod appears to be the better option because of several different factors:

• The python bindings use the libgpiod library underneath, which itself is written in c
• We already have multiple other libraries using libgpiod, so adding it is much simpler
• Looking at the source, gpiozero appears to be a pure python implementation

On the other hand, Raspberry Pi is recommending gpiozero as the replacement to use on the the Raspberry Pi 5. So it's time to compare them head to head on speed alone. In order to test the speed, each library will turn a GPIO on and off as rapidly as possible and the results will be measured with a logic analyzer. The environment will be a fresh install of the 64-bit lite version or Raspberry Pi OS Bookworm since that is the minimum that the Raspberry Pi 5 requires. The scripts will be running inside of a virtual environment as is recommended now.

First up will be libgpiod. The script that will be used is:

Next up is gpiozero. The script that will be used is:

How many matrix panels can you use with the Matrix Portal S3?  Theoretically, around 50, however the more panels you add the greater the travel distance and signal degradation. Degraded signals can have effects of pixel artifacts/glitching and visible scan lines that are very hard on the eyes. 

The bit depth (amount of possible colors) is also very important. 12 panels cannot stream more than a bit depth of 4 without significant artifacts.  Normally with Circuit Python, images are 8-bit indexed BMP's but matrix panels can only display a maximum of 6-bit color. A TFT can support up to 24-bit so do not make the mistake of treating a matrix display like a TFT. It will still process 8-bit indexed BMP's with some image quality loss due to the nature of RGB LED's in a matrix panel.

For this project I'm using 12x 5mm pitch matrix panels. The pitch denotes the physical distance between pixels. A 3mm pitch panel will be much smaller physically than a 6mm pitch for example.

Panel Arrangement

The serpentine arrangement of the panels matters.  If you get it wrong you'll end up re-arranging the entire matrix until you get it right. The RGB Matrix library expects the controller (Matrix Portal S3) to be in the top right of any arrangement regardless of post-processing rotation in the code. The library expects each 2nd row to have the panels flipped 180 degrees as shown below. You can have each row or column with as many panels as you want so long as the rules of the serpentine arrangement are adhered to.

The project aims to create a soap bubble machine using a perforated plastic disc attached to a DC motor and a fan.

🫧 Introduction:

The project aims to create a soap bubble machine using a perforated plastic disc attached to a DC motor and a fan. These components are connected to an L298 driver circuit and controlled by a Raspberry Pi Pico microcontroller. This simple and enjoyable project is designed for children to learn about electronics and programming.

Soap bubbles have always fascinated children and adults alike. They bring joy and excitement, creating beautiful floating spheres that reflect light in mesmerizing colors. With this project, children can explore the science behind soap bubbles while having fun building their own machine.

The heart of the machine is the perforated plastic disc, which acts as a bubble wand. When the disc rotates, it dips into a soap solution, creating a film of soap on its surface. As the disc spins, air from the fan blows through the holes, forming bubbles that detach from the disc and float away.

To control the rotation of the disc and fan speed, we use a DC motor connected to an L298 driver circuit. The L298 driver allows us to control the direction and speed of the motor using signals from the Raspberry Pi Pico microcontroller.

We control the speed of the perforated circular bubbles disc through a potentiometer connected to an ADC pin at the Raspberry Pi Pico.

The Raspberry Pi Pico serves as the brain of our project. It runs a program that controls when to start and stop the motor, as well as adjusting its speed. By programming the Raspberry Pi Pico, children can learn about coding concepts such as loops, conditionals, and functions.

This project not only introduces children to basic electronics but also encourages their creativity by allowing them to customize their bubble machine. They can design and decorate their own plastic discs or experiment with different fan sizes for varying bubble sizes.

In conclusion, this DIY project offers an exciting opportunity for children to learn about electronics, programming, and physics while having fun creating their own soap bubble machine. It combines science with creativity in an engaging way that will captivate young minds. So let's dive into this project together and explore the fascinating world of soap bubbles!

The following picture shows the Raspberry Pi Pico pinout (which functions are supported by each pin).

🫧 How to Initialize PWM in MicroPython for Raspberry Pi Pico?

We are going to follow the steps stated below in order to configure PWM in our Raspberry Pi Pico.

• Firstly, we have to choose the PWM pin.
• Next, we set a particular frequency for our digital signal. 50Hz is a good value to start off with to work with an LED and L298.
• Raspberry Pi Pico has 12 bit resolution but in MicroPython it is scaled to 16 bits. Hence the duty cycle will be set from 0-65535 which corresponds to 0-100%

You can read this article on Raspberry Pi Pico ADC:

• Raspberry Pi Pico ADC with Voltage Measurement Examples

Inside the infinite loop we are reading the analog pin through the method read_u16() from the potentiometer variable and storing it in potentiometer_value. This value will vary from 0-65536 because we have 16 bit resolution. You will be able to see the values getting printed on the screen. This value is given as a parameter inside the duty_u16() method which is being accessed through the led and motor speed.

When you run this code on your Raspberry Pi Pico and rotate the potentiometer knob, you will get the value of ADC after every 1 seconds.

Increasing input values from the potentiometer act as increasing duty cycle hence the brightness of the led increases and the speed of motor of bubbles disk..

The blower fan and Raspberry Pi Pico were powered by a power bank. The drive module L298 is powered by an external battery.

Note:

• The smaller the disc area, the greater the possibility of bubbles sticking to each other, so it is preferable to use a larger disc with proper spacing of the holes.
• You should also use a powerful fan to blow bubbles, such as fans that rely on a Brushless motor.
• Using a variable resistor (potentiometer) we calibrate the disk speed to obtain the desired performance.

🫧 Test The Machine 🫧😊🫧

1 - Wokwi Simulation Test:

https://wokwi.com/projects/374559373412279297

2 - Real Test :

https://www.hackster.io/aula-jazmati/diy-bubble-machine-using-raspberry-pi-pico-9f2a54

 

 

Make a robot that reacts to gestures by waving its arms in a cheer!

Introduction:

In this project, we aim to create an interactive paper robot using Hexabitz modules. The robot will be equipped with a servo motor and a motion sensor, enabling it to move its arms and wave in response to any movement detected by the sensor. By combining the versatility of Hexabitz with the simplicity of paper, we hope to create a fun and engaging DIY project that showcases the potential of modular robotics. Whether you're a beginner or an experienced maker, this project is sure to provide a rewarding challenge and a unique addition to your robotics collection. So let's get started and bring this interactive paper robot to life!

Tools:

The DIY interactive paper robot with Hexabitz is a project aimed at designing a paper robot for children using servo motors and motion sensors. The robot is capable of moving its arms and waving whenever any movement is detected in front of the sensor.

This project combines creativity, engineering, and technology to create an interactive and engaging experience for children. By using simple materials like paper and basic electronic components, we can build a fun and educational toy that encourages children to explore the world of robotics.

The main components used in this project are servo motor, which allow the robot's arms to move in different directions, and a motion sensor that detects any movement in its vicinity.

The DIY interactive paper robot not only introduces children to basic robotics concepts but also encourages them to think creatively and problem-solve. They can customize their robots by decorating them with colors, patterns, or even adding additional features like LED lights or sound effects.

Through this project, children will learn about basic electronics, coding, and how different components work together to create a functional robot. It provides an opportunity for hands-on learning and fosters curiosity and imagination.

How I build it 🛠️

Step 1: Plan the array and assemble the hardware

We prepare the project components and plan our array design by aligning modules side-by-side.

CheerBot Template: If you need to print CheerBot templates, you can download them here: https://www.okdo.com/p/okdo-microbit-build-a-paper-robot-kit

Step 2: Writing codes with STM32CubeIDE software

H0AR9x Firmware H0AR9.h code:

First, reduce the number of ports in the.h file. This can be achieved by replacing the original number of ports with one less, and commenting out the last port along with its related USART port and UART Init prototype. For example, if the original number of ports is 6, it should be reduced to 5 by commenting out (//#define _P6), (//#define _Usart6 1), and (//extern void MX_USART6_UART_Init(void);).

H0AR9x Firmware H0AR9.c code:

Second, comment the MX_USART6_UART_Init() port inside the Module_Peripheral_Init() function in the.c file, also commenting this port inside GetPort function.

H0AR9x Firmware H0AR9_gpio.c code:

Third, add the instructions for configuring the pin you are going to use in H0AR9_gpio.c file.

GPIO_InitStruct.Pin = GPIO_PIN_8;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
HAL_GPIO_Init(GPIOB,&GPIO_InitStruct);

H0AR9x Firmware main.c code:

First, we define the motion variable:

uint16_t prox;

and then defined the other variable used in the code.

int q;

And in the repeated closed loop, we made sure that MCU periodically checks the prox value of the sensor using the API from module factsheet.

SampleDistance(&prox);

And if the motion achieves the required condition (i.e. if we wave in front of the PIR motion sensor), the servo motor is turned on at certain angles to move the robot's arms.

if (q > 15)
		HAL_GPIO_WritePin(GPIOB, GPIO_PIN_8, GPIO_PIN_SET);
		Delay_ms(1.5);
		HAL_GPIO_WritePin(GPIOB, GPIO_PIN_8, GPIO_PIN_RESET);
		Delay_ms(20);
                HAL_GPIO_WritePin(GPIOB, GPIO_PIN_8, GPIO_PIN_SET);
                Delay_ms(0.5);
		HAL_GPIO_WritePin(GPIOB, GPIO_PIN_8, GPIO_PIN_RESET);
		Delay_ms(10);
                HAL_GPIO_WritePin(GPIOB, GPIO_PIN_8, GPIO_PIN_SET);
                Delay_ms(2.5);
		HAL_GPIO_WritePin(GPIOB, GPIO_PIN_8, GPIO_PIN_RESET);
		Delay_ms(50);

• Check out this project for : How is a Servo Controlled.

Note: For this project, make sure you're using the standard 180° servo.

Step 3: Test the System 🤖👋😊

In conclusion, the DIY interactive paper robot with Hexabitz is an exciting project that combines art, technology, and education. It offers an engaging way for children to learn about robotics while having fun building their own unique robots. Let's dive into this project and unleash our creativity!

https://www.youtube.com/watch?v=QbJlmUX6kw4

https://www.youtube.com/watch?v=TTemPlQt_nI

References:

• https://www.hackster.io/aula-jazmati/make-diy-interactive-paper-robot-with-hexabitz-a015bd
• https://www.okdo.com/wp-content/uploads/2023/01/Full_Booklet_v1.pdf
• https://www.instructables.com/Make-a-Ticklish-Robot/

BNo055 Sensor CircuitPython Driver GitHub:

https://github.com/adafruit/Adafruit_CircuitPython_BNO055

BNo055 Sensor ReadTheDocs:

https://docs.circuitpython.org/projects/bno055/en/latest/

Nunchuck CircuitPython Driver:

https://github.com/adafruit/Adafruit_CircuitPython_Nunchuk/blob/main/adafruit_nunchuk.py

Nunchuck ReadTheDocs:

https://docs.circuitpython.org/projects/nunchuk/en/latest/api.html#implementation-notes

I've got hundreds of Arduino libraries that we maintain in my 'libraries' folder, and it can very quickly get difficult to maintain them. There's 4 issues I spent an inordinate amount of time on!

First issue is that whenever a library is updated, the IDE does not delete the previous version, but keeps both around...after a few years this ends in a lot of cruft. 

Secondly, libraries downloaded via the IDE are placed into a folder in the format arduino_nnnnn where n is a number, so you don't really know what library is inside it, making the first issue hard to clean up

Thirdly - for Adafruit libraries, they are git clone'd into the library folder which means I sometimes end up in a branch that I'm working on, and then submit a PR. Days later I've forgotten to change back into my main branch, losing out on any merged updates!

Finally - there's constant updates to our libraries, and the IDE does alert me when this happens - which means I need to do a git pull - but in hundreds of libraries this takes a long time to go to each folder and run the git pull command.

THUS a script! This python code does a number of clean up tasks, I only have to run it a few times a week and it will keep my arduino libraries folder nice n tidy. Thanks to ChatGPT4 Sept 25 for the assist, it made the scripting faster (note I did make some changes beyond what GPT4 wrote)

The MAX98357A 3-watt I2S amplifier is wonderful way to output tunes from CircuitPython synthio, but because it produces a balanced Class-D output that only works with speakers, it doesn't interface well with standard unbalanced audio inputs on guitar amplifiers or a workstation's DAW (Digital Audio Workstation). After a couple of somewhat successful attempts to reintegrate the digital speaker signal with special analog amplifiers, it became obvious that what was really needed was an I2S stereo DAC like the discontinued Adafruit UDA1334A DAC (PID#3678).

A search of in-stock and active I2S DAC chips yielded the Texas Instruments PDM510xA family of I2S audio DACs that could meet the overarching project requirements of:

1. Provide an unbalanced ground-centered stereo line-level audio output using a single power supply.
2. A direct pin-for-pin compatible breakout stackable/replacement for the MAX98357A amplifier including shutdown capability (SD).
3. Approximately the same size as the UDA1334A breakout.

The PDM510xA family does not require a master sample clock as the internal phase-locked-loop (PLL) extracts the master clock from the bit clock (BCLK) input. Also, the ground-centered audio output is achieved with an on-chip negative voltage charge pump, eliminating the need for bandwidth-limiting DC blocking capacitors on the DAC output pins.

Assembly of the PCB (YouTube):

Overview

The TV Backlight illuminates the wall behind the TV display to reduce eye strain. The backlight extends the background of the screen image by watching the color near an edge of the display. To reduce distraction, the color and brightness are integrated over time to avoid sudden changes.

The project's CircuitPython code reads the AS7341 spectrometer sensor's eight visible light channels to determine the backlight target color. Using a Euclidean "color distance" comparison, the backlight color is slowly changed to match the target color, within a specified tolerance.

The spectrometer sensor settings are adjusted for relatively low display light levels. The sensor's internal amplifier gain is set to maximum and the integration step and time values are adjusted to maintain a moderately fast conversion rate. Also, rather than just analyzing red, green, and blue components, all eight visible light channels are used to increase the accuracy and resolution of color measurements.

In this configuration, just one of the sensor's channels can reach a count value of near 13k, producing a composite 8-channel resolution that approaches 8x10³² color combinations, much larger than the 17x10⁶ (24-bit) color resolution of the NeoPixel strip. A color count to RGB converter helper reads the three primary color sensor channels, scales the count, and produces an RGB888 (24-bit) color value that's compatible with NeoPixels.

To assist in finding a position near the TV screen for the sensor, the Feather M4's on-board NeoPixel mimics the readings in real-time, albeit at a slightly lower brightness than the illumination strip NeoPixels.

Documents

Test video: https://youtu.be/yFqbalF0FGw

Next Steps

• Build a camouflaged enclosure and vertical mounting wands for the NeoPixel strips.
• Investigate animating the NeoPixel strip color change.
• For home security, enable the NotFlix (Fake TV) code when the TV display is dark for 5 minutes or more.

CircuitPython Code

What had my interest is the combination of price and that it’s a short-throw projector. Typical LCD projectors have a focal distance of 1 meter or more, whereas short-throw varieties…normally quite spendy…focus just a few inches from the front lens, suggesting interesting and creative applications.

See, a few years back we were all agog over the Gakken Worldeye HDMI display — $150 at the time, but now discontinued and “collectible” at $400 — and were looking for economical DIY approaches which never panned out.

Background

Making my annual pilgrimage to all the Halloween stores this year, this “Jabberin’ Jack” animated Jack-o’-lantern caught my attention. It’s a fairly affordable item ($60 or less) with a tiny internal LCD projector and video player to show an animated face:

The Adafruit Controllable Four Outlet Power Relay Module is a very neat piece of hardware (if you live in a 120 volt AC country). It has a pair of contacts on the side that can take a wide range of voltages to switch electrical loads on and off. This is just what my wife wanted, a method to remotely control power outlets to some gear in her office.

But how to switch it remotely. WiFi relies on connectivity that might get hacked over the internet in our view. Bluetooth seems more secure (maybe local hacking is possible, but our locality isn't a concern). I initially picked up an Adafruit Feather ESP32-S3. But CircuitPython Bluetooth doesn't work for UART/Serial profile. I want to, for proof of concept, use the Adafruit Bluefruit LE Connect application (available for iOS and Android) to send codes for on and off. That limits my choices to the Nordic nRF52840-based microcontroller boards.

Code

I modified some example code on how to connect the nRF52840 board to the Connect app. In the Getting Started with CircuitPython and Bluetooth Low Energy guide, I modified the Button Press example to also toggle the button.TX pin high when the up arrow is pressed, low when the down arrow is pressed.

I connected my CPB to my computer with a known good data+power micro B USB cable (Adafruit sells many different ones). I used the Mu editor to copy the example code and modify it to use digitalio for the pin toggling and neopixel to use two of the colorful RGB LEDs as status lights (one for Bluetooth connected, one for the switch state).

I needed to copy several libraries over to the /lib directory on the CIRCUITPY drive with File Explorer on my computer.

• neopixel
• adafruit_ble
• adafruit_bluefruit_connect

The latest Library Bundle is on the circuitpython.org website.

Next I used Mu to save the code to a file named code.py on the CIRCUITPY drive. 

Here is the code:

Unicomp Mini M with CircuitPython

Unicomp is the heir to the IBM Buckling Spring legacy. This style of keyboard has a distinctive sound & feel which some people just can't get enough of. I'm one of them, having used a crusty old Model M for at least a decade at work.

Their "Mini M" is an 87-key ("tenkeyless") layout, and in late summer 2023 the controller was replaced with a board that has a Raspberry Pi Pico soldered on to it.

It's too soon for me to have formed a strong opinion about this keyboard, though I will note that the cable seems to be in the category of "incredibly cursed": It is a USB A-A cable, which should not exist. If your computer is USB-C only you're entering dongle city, but, you're probably used to that.

In this mini-guide, you'll learn how to replace the factory firmware with a fully customizable CircuitPython firmware. Of course, once you have the controller in UF2 bootloader mode, you could also use Arduino or Pico-SDK to program it with the software of your choice.

Note that this involves opening up the keyboard enclosure and there is always the possibility that you will damage the keyboard while doing so.

Reverse Engineering

I don't know who all to credit for the reverse engineering, but all the information I needed was in a fork of the open source keyboard controller "Vial-QMK". Here are the basics:

• Keyboard is organized as a 16x12 matrix, with the columns controlled by a pair of 8-channel muxes. Together, pico pins GP0 through GP4 select one of 16 column channels, with just one of GP3 or GP4 selected by setting to a False pin value
• The 12 row inputs are GP11 through GP22
• The LEDs are on GP6 through 8, with a common anode on GP5 (so set GP5 True always, and GP6 through 8 to False to light the corresponding LED; GP6 is Num Lock)
• The matrix has no diodes, so anti-ghosting must be done in software