pi pico

69 Articles

The board in question, with a Pi Pico soldered on, with old PCBs for macropads being used as captouch electrodes

Give Your Pi Pico Captouch Inputs For All Your Music Needs

March 31, 2024 by 11 Comments

Unlike many modern microcontrollers, RP2040 doesn’t come with a native capacitive touch peripheral. This doesn’t mean you can’t do it – the usual software-driven way works wonderfully, and only requires an external pullup resistor! In case you wanted a demonstration or you have a capacitive touch project in mind, this lighthearted video by [Jeremy Cook] is a must watch, and he’s got a healthy amount of resources for you in store, too!

In this video, [Jeremy] presents you with a KiCad schematic and an PCB design you can use to quickly add whole 23 capacitive touch sensing inputs to a Pi Pico! The board is flexible mechanically, easy to assemble as [Jeremy] demonstrates, and all the pins involved can still be used as regular GPIOs if you’d like. Plus, it’s fully open-source, can easily be assembled on your own, and available on Tindie too!

Of course, such a board doesn’t get created for no reason – [Jeremy] has a healthy amount of musical creations and nifty ideas to show off. We quite liked the trick of using old PCBs as capacitive touch sensing, using copper fills as electrodes – which has helped create an amusing “macropad of macropads”, and, there’s quite a bit more to see.

If capacitive touch projects ever struck a chord with you and you enjoy music-related hacking, [Jeremy]’s got a whole YouTube channel you ought to check out. Oh, and if one of the musical projects in the video caught your eye, it might just be the one we’ve featured previously! Continue reading “Give Your Pi Pico Captouch Inputs For All Your Music Needs” →

Playing Audio On The Pi Pico With No DAC To Speak Of

March 12, 2024 by 24 Comments

Normally, if you want to play music or other audio on a microcontroller, you need to get yourself a DAC. Or at least, that’s the easiest way to go about it and the one most likely to get you good, intelligible audio. You don’t have to go that way, though, as [antirez] demonstrates.

[antirez] decided to do this with a Pi Pico, but it’s applicable to other microcontrollers too. It’s all done with a single pin and a PWM output. The PWM output is set to a very high frequency beyond human hearing. In this case, it was 100 KHz. Then, the duty cycle of the PWM is changed to essentially output various average voltage levels at the pin. Vary the output voltage as per your desired sound file by using each sample to vary the duty cycle of the PWM. Voila! You can output whatever sound you want on that pin! [antirez] steps through the basics of doing this, including processing simple WAV files into a raw format that can be dumped into MicroPython code.

There’s no sound sample on the project page, and we’d have to assume it sounds pretty crunchy when hooked up to a speaker. And yet, it could prove a useful technique if you’re designing your own audio greeting cards or something, so keep that in mind!

Pi Pico Enhances RadioShack Computer Kit

February 20, 2024 by 9 Comments

While most of us now remember Radio Shack as a store that tried to force us to buy batteries and cell phones whenever we went to buy a few transistors and other circuit components, for a time it was an innovative and valuable store for electronics enthusiasts before it began its long demise. Among other electronics and radio parts and kits there were even a few DIY microcomputers, and even though it’s a bit of an antique now a Raspberry Pi Pico is just the thing to modernize this Radio Shack vintage microcomputer kit from the mid 80s.

The microcomputer kit itself is built around the 4-bit Texas Instruments TMS1100, one of the first mass-produced microcontrollers. The kit makes the processor’s functionality more readily available to the user, with a keypad and various switches for programming and a number of status LEDs to monitor its state. The Pi Pico comes into the equation programmed to act as a digital clock with an LED display to drive the antique computer. The Pi then sends a switching pulse through a relay to the microcomputer, which is programmed as a binary counter.

While the microcomputer isn’t going to win any speed or processing power anytime soon, especially with its clock signal coming from a slow relay module, the computer itself is still fulfilling its purpose as an educational tool despite being nearly four decades old. With the slow clock speeds it’s much more intuitive how the computer is stepping through its tasks, and the modern Pi Pico helps it with its tasks quite well. Relays on their own can be a substitute for the entire microcontroller as well, like this computer which has a satisfying mechanical noise when it’s running a program.

Continue reading “Pi Pico Enhances RadioShack Computer Kit” →

Sonolithography With The Raspberry Pi Pico

February 16, 2024 by 5 Comments

You can do some wild things with sound waves, such as annoy your neighbours or convince other road users to move out of your way. Or, if you get into sonolithography like [Oliver Child] has, you can make some wild patterns with ultrasound.

Sonolithography is a method of patterning materials on to a surface using finely-controlled sound waves. To achieve this, [Oliver] created a circular array of sixteen ultrasonic transducers controlled via shift registers and gate driver ICs, under the command of a Raspberry Pi Pico. He then created an app for controlling the transducer array via an attached computer with a GUI interface. It allows the phase and amplitude of each element of the array to be controlled to create different patterns.

Creating a pattern is then a simple matter of placing the array on a surface, firing it up in a given drive mode, and then atomising some kind of dye or other material to visualize the pattern of the acoustic waves.

It could be a useful tool for studying the interactions of ultrasonic waves, or it could just be a way to make neat patterns in ink and dye if that’s what you’re into. [Oliver] notes the techniques of sonolithography could also have implications in biology or fabrication in future, as well. If you found this interesting, you might like to study up on ultrasonic levitation, too!

Saving PIC Microcontrollers With DIY Programmer

January 14, 2024 by 32 Comments

When working on a project, plenty of us will reach for an Atmel microcontroller because of the widespread prevalence of the Arduino platform. A few hackers would opt for a bit more modern part like an ESP32. But these Arduino-compatible platforms are far from the only microcontrollers available. The flash-based PIC family of microcontrollers is another popular choice. Since they aren’t quite as beginner or user-friendly, setting up a programmer for them is not as straightforward. [Tahmid] needed to program some old PIC microcontrollers and found the Pi Pico to be an ideal programmer.

The reason for reaching for the Pico in the first place was that [Tahmid] had rediscovered these decade-old microcontrollers in a parts bin but couldn’t find the original programmer. Thanks to advances in technology in the last ten years, including the advent of micropython, the Pico turned out to be the ideal programmer. Micropython also enables a fairly simple drag-and-drop way of sending the .hex file to the PIC, so the only thing the software has to do is detect the PIC, erase it, and flash the .hex file. The only physical limitation is that the voltages needed for the PIC are much higher than the Pico can offer, but this problem is easily solved with a boost converter (controlled by the Pico) and a level shifter.

[Tahmid] notes that there’s plenty of room for speed and performance optimization, since this project optimized development time instead. He also notes that since the software side is relatively simple, it could be used for other microcontrollers as well. To this end, he made the code available on his GitHub page. Even if you’re more familiar with the Arduino platform, though, there’s more than one way to program a microcontroller like this project which uses the Scratch language to program an ESP32.

Pico-Sized Ham Radio

January 10, 2024 by 18 Comments

There are plenty of hobbies around with huge price tags, and ham radio can certainly be one of them. Experienced hams might have radios that cost thousands of dollars, with huge, steerable antennas on masts that can be similarly priced. But there’s also a side to the hobby that throws all of this out of the window in favor of the simplest, lowest-cost radios and antennas that still can get the job done. Software-defined radio (SDR) turned this practice up to 11 as well, and this radio module uses almost nothing more than a microcontroller to get on the air.

The design uses the capabilities of the Raspberry Pi Pico to handle almost all of the radio’s capabilities. The RF oscillator is driven by one of the Pico’s programmable I/O (PIO) pins, which takes some load off of the processor. For AM and SSB, where amplitude needs to be controlled as well, a PWM signal is generated on another PIO which is then mixed with the RF oscillator using an analog multiplexer. The design also includes a microphone with a preamplifier which can be fed into a third PIO; alternatively it can receive audio from a computer via the USB interface. More processor resources are needed when generating phase-modulated signals like RF, but the Pico is still quite capable of doing all of these tasks without jitter larger than a clock cycle.

Of course this only outputs a signal with a few milliwatts of power, so for making any useful radio contacts with this circuit an amplifier is almost certainly needed. With the heavy lifting done by the Pico, though, the amplifier doesn’t need to be complicated or expensive. While the design is simple and low-cost, it’s not the simplest radio possible. This transmitter sends out radio waves using only a single transistor but you will be limited to Morse code only.

Continue reading “Pico-Sized Ham Radio” →

The Pi Pico replacement board in question, assembled, held diagonally in some type of holder

ProPico For Your Pro Pico Needs

January 3, 2024 by 6 Comments

Ever feel like the Pi Pico board could be doing way more given its footprint? Does it bother you that the RP2040’s ADC quality is even further decreased because of the noisy onboard switching regulator? Miffed about decisions like the MicroUSB socket, the 2MB flash, or lack of the reset button? [Dmytro] brings us an open-source Pi Pico design, sporting the same RP2040 and a fully compatible footprint, but adding a number of improvements to its surroundings.

There’s a good few additions, all of them hacker-friendly – [Dmytro] adds comfortably-spaced reset and boot buttons, a USB-C socket, a dedicated low-noise voltage reference for the ADC, one more LED, and an I2C EEPROM footprint socket that is compatible with FRAM chips. Everything worth preserving is preserved – the pinout stays the same, including the SWD connector, which now sports an extra RESET pin. The bottom side USB testpoints remain, with only the four testpoints changed for more useful signals. Last but not least, the switching regulator is replaced by the venerable 1117 – you lose the ability to power your Pico from two AAs, and the capacitor series resistor requirement isn’t great, but you can easily put one of the drop-in 1117 replacement regulators on there.

What’s great is that the design is fully open-source, with KiCad files available. Want to design your own Pi Pico footprint board, improve upon this one even further, or maybe make a more tailored one? Treat yourself to the GitHub repository! There’s also a pinout diagram and a KiCanvas schematic for all your tinkering needs. We’ve covered drop-in replacements for classic drawer-inhabiting parts like the Pi Zero, for the 7805 (twice!), the 6502 CPU, and even for the DE9 serial port connector. No matter the purpose, they’re always a joy to see.