Bluepad32 Brings All The Controllers To Your MCU

May 7, 2024 by 13 Comments

As much as we enjoy spinning up our own solutions, there are times when you’ve got to look at what’s on the market and realize you might be out of your league. For example, take Bluetooth game controllers. Sure, you could make your own with a microcontroller, some buttons, and a couple joysticks. But between the major players like Microsoft, Nintendo, and Sony, as well as independent peripheral companies like 8BitDo, there’s some seriously impressive hardware out there that can be easily repurposed.

How, you ask? Well, Bluepad32 by [Ricardo Quesada] would be a great place to start. This Apache v2.0 licensed project allows you to easily interface with a wide array of commercially available BT controllers, and supports an impressive number of software and hardware platforms. Using the Arduino IDE on the ESP32? No problem. CircuitPython on Adafruit’s PyPortal? Supported. There’s even example code provided for using it on Linux and Mac OS. Sorry Windows fans — perhaps there’s a sassy paperclip or sentient dog built into your OS that can instruct you further.

A few of the controllers supported by Bluepad32.

The nature of the Bluetooth Human Interface Device (HID) protocol means that, at least in theory, pretty much all modern devices should be supported by Bluepad32 automatically. But even still, it’s hard not to be impressed by the official controller compatibility list. There’s also separate lists for Bluetooth mice and keyboards that are known to work with the project.

While it’s somewhat unlikely to be a problem in this particular community, there is an unusual quirk to this project which we think should at least be mentioned. Although Bluepad32 itself is free and open source software (FOSS), it depends on the BTstack library, which in turn uses a more ambiguous licensing scheme. BTstack is “open” in the sense that you can see the source code and implement it in your own projects, but its custom license precludes commercial use. If you want to use BTstack (and by extension, Bluepad32) in a commercial product, you need to contact the developers and discuss terms.

License gotchas aside, Bluepad32 is definitely a project to keep in the back of your mind for the future. You can always build your own controller if you’re looking a challenge, but you’ll have a hell of a time beating the decades of testing and development Sony has put into theirs.

Human-Interfacing Devices: HID Over I2C

April 17, 2024 by 15 Comments

In the previous two HID articles, we talked about stealing HID descriptors, learned about a number of cool tools you can use for HID hacking on Linux, and created a touchscreen device. This time, let’s talk about an underappreciated HID standard, but one that you might be using right now as you’re reading this article – I2C-HID, or HID over I2C.

HID as a protocol can be tunneled over many different channels. If you’ve used a Bluetooth keyboard, for instance, you’ve used tunneled HID. For about ten years now, I2C-HID has been heavily present in laptop space, it was initially used in touchpads, later in touchscreens, and now also in sensor hubs. Yes, you can expose sensor data over HID, and if you have a clamshell (foldable) laptop, that’s how the rotation-determining accelerometer exposes its data to your OS.

This capacitive touchscreen controller is not I2C-HID, even though it is I2C. By [Raymond Spekking], CC-BY-SA 4.0
Not every I2C-connected input device is I2C-HID. For instance, if you’ve seen older tablets with I2C-connected touchscreens, don’t get your hopes up, as they likely don’t use HID – it’s just a complex-ish I2C device, with enough proprietary registers and commands to drive you crazy even if your logic analysis skills are on point. I2C-HID is nowhere near that, and it’s also way better than PS/2 we used before – an x86-only interface with limited capabilities, already almost extinct from even x86 boards, and further threatened in this increasingly RISCy world. I2C-HID is low-power, especially compared to USB, as capable as HID goes, compatible with existing HID software, and ubiquitous enough that you surely already have an I2C port available on your SBC.

In modern world of input devices, I2C-HID is spreading, and the coolest thing is that it’s standardized. The standardization means a lot of great things for us hackers. For one, unlike all of those I2C touchscreen controllers, HID-I2C devices are easier to reuse; as much as information on them might be lacking at the moment, that’s what we’re combating right now as we speak! If you are using a recent laptop, the touchpad is most likely I2C-HID. Today, let’s take a look at converting one of those touchpads to USB HID.

A Hackable Platform

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A new display wedged into a car-based fridge

New Brains Save 12 V Fridge From The Scrap Heap

March 14, 2024 by 17 Comments

Recently [nibbler]’s Evakool 55L vehicle fridge started to act strangely, reporting crazy temperature errors and had no chance of regulating. The determination was that the NTC thermistor was toast, and rather than trying to extricate and replace this part, it was a lot easier to add a new one at a suitable location

Bog-standard fridge internals

A straight swap would have been boring, so this was a perfect excuse for an overboard hack. Reverse engineering the controller wouldn’t be easy, as the data wasn’t available, as is often the case for many products of this nature.

While doing a brain transplant, the hacker way, we can go overboard and add the basics of an IoT control and monitoring system. To that end, [nibbler] learned as much as possible about the off-the-shelf ZH25G compressor and the associated compressor control board. The aim was to junk the original user interface/control board and replace that with a Raspberry Pi Pico W running CircuitPython.

For the display, they used one of the ubiquitous SH1106 monochrome OLED units that can be had for less than the cost of a McDonald’s cheeseburger at the usual purveyors of cheap Chinese electronics.  A brief distraction was trying to use a DS18B20 waterproof thermometer probe, which they discovered didn’t function, so they reverted to tried and trusted tech — a simple NTC thermistor.

Continue reading “New Brains Save 12 V Fridge From The Scrap Heap” →

Thumbs Up To This Pico MIDI Kalimba

March 6, 2024 by 8 Comments

The kalimba, or thumb piano, is an easy way to make some music even if you have next to no idea what you’re doing. The only real downside is that they are limited to the twinkly sounds of metal tines being plucked by thumbs.

[Jeremy Cook] broke the sonic possibilities wide open by converting a couple of kalimbas into capacitive-touch MIDI instruments using the Raspberry Pi Pico. He started with a small one that is curiously made of solid wood. Usually these instruments are at least partially hollow to allow air to resonate inside the body.

After soldering up all the 1 MΩ resistors necessary to utilize the capacitive touch capabilities of the Pico, [Jeremy] found it a bit difficult to play individual notes on such a small instrument, so he made version two out of a much larger specimen.

This time, [Jeremy] cooked up a custom PCB which he is calling the Pico Touch 2, which adds the necessary resistors at the SMD level for capacitive touch sensing and in turn cleans up the wiring a bit. Be sure to check it out in action after the break.

Okay, so you don’t have an iota of musical talent. You could always build a kalimba that plays itself.

Continue reading “Thumbs Up To This Pico MIDI Kalimba” →

Human-Interfacing Devices: Packing For The Descriptor Heist

February 6, 2024 by 4 Comments

We started with figuring out HID descriptors a week ago, and I’ve shown you how to send raw HID packets using a MicroPython fork. We do still have the task in front of us – making a touchscreen device. For that, let’s give you the tools to capture an existing descriptor from a touchscreen, then show you how to tweak it and how it turns out in the end.

Packing For The Heist

When it comes to this kind of adventure, we can’t go without tools and weapons – it could be dangerous! Without them, you could even abandon your project halfway! Here’s enough high-precision tools and ammunition to last you through whatever obstacles you might encounter. Except for the web-based tools, these tools are for Linux, but please remember that you can always use a virtual machine or a Raspberry Pi. Nobody would use Windows for a heist anyway, what’s with all the telemetry and such.

The first tool is for reading descriptors – we need one to learn from, it’s just like a keycard you can flash to a security guard and scan at the vault entry. Of course, with RFID, you want to have enough examples, compare bits between a few cards and all. For now, HID descriptors don’t have authenticity checks, but it looks like that might just change in the future. Leave it to Apple and Microsoft to add them, as usual. On Linux, seeing descriptors is simple – as root, go into /sys/bus/usb/devices/, find your device by its lsusb device tree path, then follow the directory with the VID/PID in it. That directory will contain a report_descriptor file – hexdump it. The entire command could look like this:

sudo hexdump -v -e '/1 "%02X "' /sys/bus/usb/devices/3-6.2/3-6.2\:1.1/0003\:0C40\:8000.0022/report_descriptor

Again, you might need root to even find this path, so use sudo -i if you must. The format string in the hexdump command gives you parser-friendly output. Specifically, for parsing, I use this webpage – it’s wonderful, even adding tabs that delineate different sections of the descriptor, making its output all that more readable! You can also save this webpage locally, it’s a very neat tool. Other than that, you can try other local tools like this one!

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Human-Interfacing Devices: The Descriptor Heist

January 30, 2024 by 9 Comments

Today, we’ll build our own input devices. And they will be easy to create and write firmware for, they will work perfectly, and they will be cross-platform. We can do that with help of the Human Interface Device (HID) standard, and by way of introduction, so that you never get confused by what a “descriptor” means, and we’ll build our own HID device — a Human Interface Device device. The way we build them won’t require reading specifications – instead, I’ll teach your how to steal HID descriptors from existing devices, tweak them for our purposes, and use them in our devices to harness the power of HID.

For decades now, it’s been possible to build a HID mouse or keyboard by using a library or two, and it’s been a godsend for hackers all around the world. However, these libraries are typically confined to a certain template and inflexible, and we hackers often go outside of what’s expected. HID allows for much more than a simple keyboard or a mouse. That’s why today we’re building a touchscreen – something not yet covered online or by libraries.

HID lets you build devices that are friendly. They don’t need drivers, they are plug and play, and they do what you expect them to do. At its core, the HID standard is as simple as is ubiquitous. You can tunnel HID over USB, Bluetooth, I2C, and modern-day operating systems support all three of these. Today, let’s go through the basics of HID, and then build a USB touchscreen out of a SPI-connected resistive touchscreen, with help of the usual RP2040+MicroPython combo. I will also give you a toolkit for how to debug a Human Interface Device device as thoroughly as possible – specifically on Linux, showing all the HID debug and introspection capabilities that Linux gives you. But it’ll work on Windows too through the beauty of standardization.

Continue reading “Human-Interfacing Devices: The Descriptor Heist” →

When Is A Typewriter A Printer? When It Has A Parallel Port

December 14, 2023 by 13 Comments

If you want to talk to a typewriter using something other than your fingers on the keys, you could do a lot worse than to pick up a specimen featuring a Centronics parallel port. That’s what happened to [mlupo], who came across an old Swintec 1146 CMP and decided to hack it into an art installation.

At the push of a giant, clicky button, the typewriter now spits out family stories. This is all thanks to an Adafruit KB2040 keyboard driver being used in a new, exciting way — as a printer driver.

More specifically, the CircuitPython program running on the KB2040 takes in a text file and then sends the data one character at a time until a newline is reached. At that point, the typewriter sends a busy signal and the characters are typed.

As soon as the typewriter is no longer occupied, the data stream picks back up until the next newline or until the file is completely typed out.

Once [mlupo] figured out enough of the parallel port protocol, they were able to build a custom breakout board with the KB2040, a female parallel port, and a row of LEDs for debugging that [mlupo] kept because they look cool.

The KB2040 sets the values high on a series of the parallel port’s data pins, along with the port’s STROBE pin, which pulls low when data is ready. During each STROBE cycle, the high and low pins are read by the Swintec as a binary character.

Of course, you can always use the power of Pi to build your own modern typewriter.

Thanks to [foamyguy] for the tip!