PiSquare Lets You Run Multiple HATs On A Raspberry Pi

April 13, 2022 by Lewin Day 8 Comments

The Raspberry Pi’s venerable 40-pin header and associated HAT ecosystem for upgrades has been a boon for the platform. It’s easy to stack extra hardware on to a Pi, even multiple times in some cases. However, if you want to run multiple HATs, and wirelessly at that, the PiSquare might just be the thing for you.

The PiSquare consists of a board featuring both RP2040 and ESP-12E microcontrollers. It interfaces with Raspberry Pi HATs and even lets you run multiple of the same HAT on a single Raspberry Pi, as it’s not actually directly using the UART, SPI, or I2C interfaces on the host Pi itself. Instead, the PiSquare communicates wirelessly with the Pi, handling the IO with the HAT itself.

It’s unclear how this works on a software level. Simply using existing software tools and libraries for a given Raspberry Pi HAT probably won’t work with the wireless PiSquare setup. However, for advanced users, it could serve a useful purpose, allowing one Raspberry Pi to command multiple HATs without the fuss of having to run more single-board computers where just one will do. Boards will be available on Kickstarter for those interested in the device.

We’ve seen other creative things done with the Raspberry Pi and the HAT system, too. If you’ve been cooking up your own neat hacks for the platform, drop us a line!

ayan-sensor2notion-dashboard+raspberryPi

Know Which Way The Wind Blows, Whether Weather Boosts Your Mood

March 31, 2022 by Michael Shaub 4 Comments

As a quantified-self experiment, [Ayan] has tracked several daily habits and moods for a couple of years and discovered some insights. Too much coffee is followed by anxiety while listening to music leads to feelings of motivation and happiness. There was a strong correlation in the data, but [Ayan] wondered if external factors like the weather and air quality also played a role.

To find out, [Ayan] extended the custom dashboard built in Notion.so with weather data and some local sensors. Working at Balena.io (yes, the makers of the ubiquitous Raspberry Pi SD card flashing tool, Etcher), [Ayan] turned to balenaCloud to translate the data from (you guessed it) a Raspberry Pi into the dashboard via Notion’s API beta. We think Notion holds a lot of promise for all sorts of web-based dashboards as a research notebook and organizational tool. Who knows where the API will lead any interested readers?

Check out the full tutorial where [Ayan] walks you through the hardware used and each step to connect the APIs that bring it all together. [Ayan] plans to add a coffee-maker integration to automate that data entry and would welcome help getting a manual trigger set up for the data integrations.

New Part Day: Raspberry Pi HAT For IEEE1588 Precision Time Protocol

August 16, 2021 by Dave Rowntree 18 Comments

The new Real-Time HAT by InnoRoute adds IEEE1588 PTP support in hardware to a Raspberry Pi 4 nestled beneath. Based around a Xilinx Artix-7 FPGA and a handful of gigabit Ethernet PHY devices, the HAT acts as network-passthrough, adding accurate time-stamps to egress (outgoing) packets and stripping time-stamps from the ingress (incoming) side.

This hardware time-stamping involves re-writing Ethernet packets on-the-fly using specialised network hardware which the Raspberry Pi does not have. Yes, there are software-only 1588 stacks, but they can only get down to 10s of microsecond resolutions, unlike a hardware approach which can get down to 10s of nanoseconds.

1588 is used heavily for applications such as telecoms infrastructure, factory equipment control and anything requiring synchronisation of data-consuming or data-producing devices. CERN makes very heavy use of 1588 for its enormous arrays of sensors and control equipment, for all the LHC experiments. This is the WhiteRabbit System, presumably named after the time-obsessed white rabbit of Alice In Wonderland fame. So, if you have a large installation and a need for precisely controlling when stuff happens across it, this may be just the thing you’re looking for.

IEEE1588 PTP Synchronisation

The PTP client and master device ping a few messages back and forth between themselves, with the network time-stamper recording the precise moment a packet crosses the interface. These time-stamps are recorded with the local clock. This is important. From these measurements, the time-of-flight of the packet and offset of the local clock from the remote clock may be calculated and corrected for. In this way each client node (the hat) in the network will have the same idea of current time, and hence all network packets flowing through the whole network can be synchronised.

The beauty of the system is that the network switches, wiring and all that common infrastructure don’t need to speak 1588 nor have any other special features, they just need to pass along the packets, ideally with a consistent delay.

The Real-Time HAT configures its FPGA via SPI, straight from Raspberry Pi OS, with multiple applications possible, just by a change on the command line. It is possible to upload custom bitstreams, allowing the HAT to be used as a general purpose FPGA dev board should you wish to do so. It even stacks with the official PoE HAT, which makes it even more useful for hanging sensors on the end of a single wire.

Of course, if your needs are somewhat simpler and smaller in scale than a Swiss city, you could just hack a GPS clock source into a Raspberry Pi with a little soldering and call it a day.

Rasberry Pi PoE Hat Released

August 26, 2018 by Brian Benchoff 37 Comments

It was announced at the beginning of March, but now the Raspberry Pi Power over Ethernet (PoE) hat is out. Thanks to the addition of a new 4-pin header on the Raspberry Pi 3 Model B+, the Pis can get power from an Ethernet cable, provided you’ve got the setup to deliver PoE.

This is a remarkable bit of engineering, even though it’s just adding Power over Ethernet to a small single board computer. Mechanically, the PoE hat doesn’t increase the 3D bounding box volume of the Raspberry Pi at all. It adds cooling with a fan controlled over I2C. Even more bizarrely, the transformer is mounted in a PCB cutout, and we’re desperate to know how that was specced, designed, and assembled. Yeah, it might just be an add-on for the Raspberry Pi, but there’s some clever work that went into designing it.

The Raspberry Pi gained PoE capability with the introduction of the Raspberry Pi 3 Model B+ last March, a release that did require a slight change to the hardware and pinout of the Raspberry Pi. Compared to the Pi 3 Model B, the Pi 3 Model B+ sports a four-pin header right next to the Ethernet jack and one of the mounting holes. This is the same location of the ‘Run’ header found in the Pi 3 Model B, and probably caused much consternation to anyone who built a hat to take advantage of having a real power button on their Pi.

Nevertheless, what’s done is done, and now we have a real PoE solution for the Raspberry Pi. This is bound to be a boon for anyone who wants to build a Raspberry Pi cluster computer, or anyone who is dropping a few Pis into a server rack that already has PoE hardware.

You can pick up a PoE Pi hat through the usual suspects (Farnell, RS, and other resellers) for $20.

Pi Replaces Keiko-chan

November 30, 2017 by Anool Mahidharia 20 Comments

[Tobias Kuhn] and a handful of colleagues at his workplace built Crystal Signal Pi, a Raspberry Pi based low-cost alternative for a notification device that provides visual, audio and network warnings about server problems. [Tobias] works for a Japanese company where it is critical for their servers to keep humming nicely all the time. Any emergencies or error conditions must be broadcast immediately so the technicians can fix it ASAP. Network enabled warning light stalks are used to provide these alerts. A local company produces a series of indicator and hazard warning lights which are colloquially called as Keiko-chan. These are similar to the hazard warning tower lights commonly fixed on machines on factory floors or many kinds of vehicles such as fork lifts. The Kieko-chans add a few bells and whistles making them more suitable for use in the server data centre — a Gigabit LAN port for wired networks and a USB port for WiFi modules. So, besides visual and audio warnings, it can also transmit messages over the network to alert the maintenance folks. Using this commercial solution should not have been a problem were it not for their rather hefty price tag of almost $500 per pop.

So [Tobias] decided to build his own warning lights based around the Raspberry Pi. After two rounds of prototypes, a simple HAT was designed that could be plugged in to a Pi. Details of the hardware are sketchy, but it’s simple enough to figure out. The part list consists of a PLCC-6 style RGB LED, three transistors to drive the three LED pins, a voltage regulator with a couple of electrolytic capacitors and a large push button. A simple acrylic case, and an acrylic cylinder mounted on top of the RGB LED creates a nice edge lit effect for the indicator.

The code for the Crystal Pi is hosted on Github, and includes handy scripts to make installation easy. Once installed, the Crystal Pi can be accessed and controlled either through a web-based GUI or via the API. There are some more interesting features already implemented or scheduled for later, so do check out the blog and the repository for more. Check out the video below to see the Crystal Pi in action.

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Pedal-Pi, Simple Programmable Guitar Pedal

September 12, 2017 by Anool Mahidharia 26 Comments

For several years, [Ray] and [Anna], the team behind ElectroSmash, have been smashing audio electronics and churning out some sweet DIY audio gear. This time around, they’ve built Pedal-Pi — a simple programmable guitar pedal based around the Raspberry-Pi Zero. It is aimed at hackers, programmers and musicians who want to experiment with sounds and learn about digital audio. A lot of effort has gone in to documenting the whole project. Circuit analysis, a detailed BoM, programming, assembly and background information on related topics are all covered on their Forum.

The hardware is split in to three parts. On the input, a MCP6002 rail-to-rail op-amp amplifies and filters the analog waveform and then a MCP3202 ADC digitizes it to a 12-bit signal. The Pi-Zero then does all of the DSP, creating effects such as distortion, fuzz, delay, echo and tremolo among others. The Pi-Zero generates a dual PWM signal, which is combined and filtered before being presented at the output. The design is all through hole and the handy assembly guide can be useful for novices during assembly. The code examples include a large number of pedal effects, and if you are familiar with C, then there’s enough information available to help you write your own effects.

Even if you don’t plan on building one, technical background such as the Basics of Audio DSP in C for Raspberry Pi Zero, Using MCP3202 ADC with Raspberry Pi Zero and PWM Audio on Raspberry Pi Zero ought to make for interesting reading. Check out the video after the break detailing the build.

If you’d like to check out some of their earlier work, check out 1WAMP, an Open Hardware Guitar Amplifier and pedalSHIELD, an opensource Arduino Guitar Pedal.

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Sense Hat Lights Up Pi

September 13, 2015 by Al Williams 15 Comments

One of our chief complaints about the Raspberry Pi is it doesn’t have a lot of I/O. There are plenty of add ons, of course to expand the I/O capabilities. The actual Raspberry Pi foundation recently created the Sense Hat which adds a lot of features to a Pi, although they might not be the ones we would have picked. The boards were made for the AstroPi project (the project that allowed UK schools to run experiments in space). They don’t appear to be officially for sale to the public yet, but according to their site, they will be selling them soon. Update: Despite some pages on the Raspberry Pi site saying they aren’t out yet, they apparently are.

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