Benchmarking Latency Across Common Wireless Links For MCUs

February 11, 2024 by 13 Comments

Although factors like bandwidth, power usage, and the number of (kilo)meters reach are important considerations with wireless communication for microcontrollers, latency should be another important factor to pay attention to. This is especially true for projects like controllers where round-trip latency and instant response to an input are essential, but where do you find the latency number in datasheets? This is where [Michael Orenstein] and [Scott] over at Electric UI found a lack of data, especially when taking software stacks into account. In other words, it was time to do some serious benchmarking.

The question to be answered here was specifically how fast a one-way wireless user interaction can be across three levels of payload sizes (12, 128, and 1024 bytes). The effective latency is measured from when the input is provided on the transmitter, and the receiver has processed it and triggered the relevant output pin. The internal latency was also measured by having a range of framework implementations respond to an external interrupt and drive a GPIO pin high. Even this test on an STM32F429 MCU already showed that, for example, the STM32 low-level (LL) framework is much faster than the stm32duino one.

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Hackaday Prize 2023: Bolt Bot Micro Servo Droids

May 9, 2023 by 1 Comment

This Hackaday prize entry from [saul] is the beginning of a reconfigurable kit of 3D printed parts and servo motors for robotics learning. With just access to a printer, a few cheap-as-chips servo motors, an Arduino, and some nuts and bolts, you could be hacking together robot walkers within a few hours of starting!

Bolt Bots is very simple to understand, with all the mechanics and wiring out there in the breeze, but strictly for indoor use we reckon. If you want to add remote control to your application, then drop in one of the ubiquitous nRF24L01 boards and build yourself a copy of the remote control [saul] handily provides in this other project.

There really isn’t a great deal we can say about this, as it’s essentially a build kit with quite a few configuration options, and you just have to build with it and see what’s possible. We expect the number of parts to proliferate over time giving even more options. So far [saul] demonstrates a few flavors of ‘walkers’, a rudimentary ‘robot arm’, and even a hanging drawbot.

The bolt hardware can be found in this GitHub repo, and the remote control code in this second one.

Servo-based designs are sometimes sneered at due to their dubious accuracy and repeatability, but with a little of effort, this can be vastly improved upon. Also, multi-legged walkers need multiple servos and controllers to drive ’em. Or do they?

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Flipper Zero Mayhem Hat Adds Camera, More Radios

March 12, 2023 by 28 Comments

For a device advertised as the “Multi-tool Device for Hackers”, the Flipper Zero already offers a considerable list of onboard capabilities. But some hard decisions had to be made to get the retail price down, so features like WiFi and Bluetooth had to be left off. Luckily, there’s an expansion interface along the top of the device which makes it possible to plug in additional hardware.

One of those expansions is the “Mayhem Hat” from [Erwin Ried]. This board adds many requested features to the Flipper Zero, as well as some that might not seem as obvious. The addition of an ESP32-CAM brings WiFi and Bluetooth to the party, while also unlocking access to the highly-capable ESP32Marauder firmware and the plethora of security research tools therein.

But the camera also enables some interesting features, such as motion detection and the ability to read QR codes. It even lets you use the Flipper as an impromptu digital camera, complete with an onscreen viewfinder reminiscent of the Game Boy Camera.

What’s more, the Mayhem Hat features its own expansion capabilities. There’s a spot to plug in either a CC1101 or NRF24l01 radio module, both of which are supported by community developed plugins that allow the user to sniff out and hijack signals. There are also extra pins for connecting your own sensors or hardware. In the demo video below you can see the device automatically detect the popular DHT11 environmental sensor and display the current temperature and humidity readings.

[Erwin] has the Mayhem Hat up for sale on Tindie, but as of this writing, is currently out of stock. Apparently, demand for the add-on boards is just as high as for the Flipper Zero itself — not a huge surprise, given the excitement we saw around this platform during its $4.8 million Kickstarter campaign.

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A Hackaday.io page screenshot, showing all the numerous CH552 projects from [Stefan].

All The USB You Can Do With A CH552

March 3, 2023 by 12 Comments

Recently, you might have noticed a flurry of CH552 projects on Hackaday.io – all of them with professionally taken photos of neatly assembled PCBs, typically with a USB connector or two. You might also have noticed that they’re all built by one person, [Stefan “wagiminator” Wagner], who is a prolific hacker – his Hackaday.io page lists over a hundred projects, most of them proudly marked “Completed”. Today, with all these CH552 mentions in the Hackaday.io’s “Newest” category, we’ve decided to take a peek.

The CH552 is an 8-bit MCU with a USB peripheral, with a CH554 sibling that supports USB host, and [Stefan] seriously puts this microcontroller to the test. There’s a nRF24L01+ transceiver turned USB dongle, a rotary encoder peripheral with a 3D-printed case and knob, a mouse wiggler, an interface for our beloved I2C OLED displays, a general-purpose CH55x devboard, and a flurry of AVR programmers – regular AVRISP, an ISP+UPDI programmer, and a UPDI programmer with HV support. Plus, if USB host is your interest, there’s a CH554 USB host development board specifically. Every single one of these is open-source, with PCBs designed in EasyEDA, the firmware already written (!) and available on GitHub, and a lovingly crafted documentation page for each.

[Stefan]’s seriously put the CH552 to the test, and given that all of these projects got firmware, having these projects as examples is a serious incentive for more hackers to try these chips out, especially considering that the CH552 and CH554 go for about 50 cents a piece at websites like LCSC, and mostly in friendly packages. We did cover these two chips back in 2018, together with a programming guide, and we’ve seen things like badges built with its help, but having all these devices to follow is a step up in availability – plus, it’s undeniable that all the widgets built are quite useful by themselves!

Dial-Up Internet Over WhatsApp

November 13, 2022 by 42 Comments

As we returned from Supercon 2022, we noticed many airlines offer free in-flight messaging. While the messages are handy for complaining about the seat size, it isn’t quite as exciting as access to the internet. In the air, we wondered how hard it would be to tunnel an internet connection over messaging. Funny enough, [Aleix Rodríguez Alameda] has a project that does exactly that by tunneling traffic over Whatsapp.

In [Aleix]’s case, cell carriers are pretty stingy with internet data when traveling in South America but often give unlimited WhatsApp data. So, ahead of time, two accounts are set up. A server is on one account and acts as a proxy to the broader internet and listens to messages to the server account. Then when in a restricted access setting, the client connects with a WebSocket and sends messages. The real trick for turning the WhatsApp messages into an internet connection the client can use is exposing a port from a local nodeJS web server. It connects to the WhatsApp API through a WebSocket and then acts as a proxy. Then, you set up traffic to be redirected through that port with curl or Firefox.

Packets are split to prevent you from sending too many messages, as in their testing, [Aleix]’s accounts were banned quickly. You shouldn’t expect massively fast speeds, as 300kbps was pretty typical during testing, which according to Wikipedia, is about what dial-up got with V.44 compression.

Which is around the same speed as TCP/IP tunneled over NRF23L01 radios.

An NRF24L01 module soldered onto a 6502 single-board computer

Wireless Bootloader Saves You From Swapping ROM Chips

April 5, 2022 by 14 Comments

Flashing your code into an Arduino, an ESP32 or any other modern microcontroller platform is pretty straightforward: connect the device through USB, fire up the appropriate software platform, and press “program”. But those who followed embedded programming classes in the ’80s and ’90s will remember a more complicated procedure that consists of swapping EPROM chips between a programmer, a target board and a UV eraser. Veterans of that era might even remember how you could overwrite a previous program with NOPs and place new code behind it, to save yourself a trip to the “blank chips” bin.

If you’re a retrocomputer enthusiast and would like to have the easy programming of modern tools, but the authenticity of a self-contained ROM-loading computer, you might want to check out [Anders Nielsen]’s latest design of a wireless boot loader for a 6502 single board computer. The target platform for this project is a beautiful custom-made 6502-based retrocomputer that [Anders] documented in detail on his Hackaday.io page.

The basic idea here is to have a wireless receiver on the target system that receives data from a transmitter connected to a modern PC. When you click “program”, the object code is sent to the 6502 machine, stored in RAM and executed. The wireless link is implemented with a pair of nRF24L01 2.4 GHz modules that communicate through SPI. Since [Anders]’s Mac Mini doesn’t come with GPIO ports he hooked up the transmitter to a Raspberry Pi which he controlled through a network link.

On the 6502 side he wrote a bootloader in assembly language, which bit-bangs the SPI protocol to communicate with the wireless module. A simple user interface is included to allow the user to control the loading and running of programs. All code and hardware documentation is available on Github for use by anyone with a similar 6502 system.

Those nRF24L01s are versatile little things: we’ve seen them being used to transfer anything from MIDI data to TCP/IP links, as well as code for other microcontroller platforms.

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Mechanical Musical Sculpture Recalls The Four Muses

November 24, 2021 by 8 Comments

Music was created by humans, but often we find ourselves creating performances with machines. [Alana Balagot] and [Federico Tobon] did just that, constructing the stunning 4 Muses musical sculpture with their combined talents.

4 Muses is made up of four individual instruments, under the command of a single keyboard controller. The keyboard can be used to play the instruments live, or alternatively, can learn from the player or be used as a sequencer. It can also act as a simple device to play back music using the four instruments.

The pipe instrument uses servo-controlled valves, which allow air from a blower fan to reach several wood pipes. The xylophone instead uses solenoids to play its 13 tines. Percussion is provided by a mechanized cajón drum, using motors to actuate mallets that strike the various sections of the box. Meanwhile, hackers will be familiar with the concept of the motor-noise instrument, which drives stepper motors at different frequencies to generate tones.

Inside, a cavalcade of microcontrollers make everything work, from Arduino Megas and Teensys to NRF24s sending wireless packets from the controller to the instruments. [Alana] and [Federico] go in-depth with their documentation, highlighting the challenges they faced putting together the various instruments and showing how the final build came together.

Built with and brass hardware and sporting a variety of exquisite wood finishes, the final result is a quartet of machines that play beautiful music composed by [Alana] herself. Musical sculptures are often a great example of the artistry possible when putting electrons to work. Video after the break.

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