raspberry pi

Monitoring my home's air quality (CO2, PM2.5, Temp/Humidity) with AirGradient's DIY sensor

A few months ago, I found this Hacker News post about the AirGradient DIY Air Quality Monitor. I had already been considering buying an AirThings Wave Plus sensor to monitor my home's CO2 levels, but the high price and limited 'ownership' of the data coming from it turned me off.

AirGradient DIY Air Quality Sensor - Focus Stacked by Jeff Geerling

So I built two AirGradient DIY air quality monitor boards (see above), and integrated them into my Prometheus + Grafana home monitoring setup I've been using to monitor other things in my house:

AirGradient DIY Grafana Dashboard for CO2 PM2.5 Temperature Humidity monitoring

Time Card and PTP on a Raspberry Pi Compute Module 4

Ahmad Byagowi, the project lead for Open Compute Project's Time Appliance, reached out to me a couple weeks ago and asked if I'd be willing to test the new Time Card Facebook had announced in mid-August on a Raspberry Pi Compute Module 4. Since I have a sort of obsession with plugging anything and everything into a Pi to see what works and what doesn't, I took him up on the offer.

The official specs had PCI Express Gen 3 on a x4 slot as a requirement, but it seems the Gen 3 designation is a little loose—the card and its driver should work fine on an older Gen 2 bus—like the one the Raspberry Pi Compute Module 4 exposes if you use the official IO Board:

Raspberry Pi Compute Module 4 IO Board PCI Express Slot

The slot is x1, but you can plug in any width card using an adapter like this one or by hacking an open end into it with a razor saw or dremel tool.

Why build a Raspberry Pi Cluster?

Raspberry Pi Cluster next to a banana for scale

After I posted my Raspberry Pi Blade server video last week, lots of commenters asked what you'd do with a Pi cluster. Many asked out of curiosity, while others seemed to shudder at the very idea of a Pi cluster, because obviously a cheap PC would perform better... right?

Before we go any further, I'd say probably 90 percent of my readers shouldn't build a Pi cluster.

But some of you should. Why?

Well, the first thing I have to clear up is what a Pi cluster isn't.

Note: This blog post corresponds to my YouTube video of the same name: Why would you build a Raspberry Pi Cluster?. Go watch the video on YouTube if you'd rather watch the video instead of reading this post!

Uptime Lab's CM4 Blade adds NVMe, TPM 2.0 to Raspberry Pi

A few weeks ago, I received two early copies of Uptime.Lab's CM4 Blade.

Uptime Lab's Raspberry Pi CM4 Blade Computer with NVMe SSD

The Blade is built for the Raspberry Pi Compute Module 4, which has the same processor as the Pi 4 and Pi 400, but without any of the built-in IO ports. You plug the CM4 into the Blade, then the Blade breaks out the connections to add some interesting features.

A 1U rackmount enclosure is in the works, and 161 of these boards would deliver:

  • 64 ARM CPU cores
  • up to 128 GB of RAM
  • 16 TB+ of NVMe SSD storage

That's assuming you can find 8 GB Compute Modules—they've been out of stock since launch almost a year ago, and even smaller models are hard to come by. More realistically, with 4 GB models, you could cram in 64 GB of total RAM.

Raspberry Pi OS now has SATA support built-in

After months of testing various SATA cards on the Raspberry Pi Compute Module 4, the default Raspberry Pi OS kernel now includes SATA support out of the box.

SATA card and Samsung SSD with Raspberry Pi Compute Module 4 IO Board

In the past, if you wanted to use SATA hard drives or SSDs and get native SATA speeds, and be able to RAID them together for redundancy or performance, you'd have to recompile the Linux kernel with SATA and AHCI.

Sure you could always use hard drives and SSDs with SATA to USB adapters, but you sacrifice 10-20% of the performance, and can't RAID them together, at least not without some hacks.

There's a video version of this post: SATA support is now built into Raspberry Pi OS!

Review: MyElectronics Raspberry Pi hot-swap rack system

MyElectronics Raspberry Pi Rack mount system

MyElectronics, a small business in the Netherlands, specializes in small computer rackmount solutions. They sent me these two racks (a 1U and 2U Raspberry Pi rack) and asked me to test them out and compare them to the 3D Printed Raspberry Pi Rack I built earlier this year, based on a design by Russ Ross.

They also have a 3U Raspberry Pi rackmount unit, but I won't be reviewing that here.

The contents of this review are summarized in this video I posted on YouTube:

Getting faster 10 Gbps Ethernet on the Raspberry Pi

If you read the title of this blog post and are thinking, "10 Gbps on a Pi? You're nuts!," well, check out my video on using the ASUS XG-C100C 10G NIC on the Raspberry Pi CM4. Back? Good.

To be clear: it's impossible to route 10 gigabits of total network throughput through any Raspberry Pi on the market today.

ASUS 10G NIC in Raspberry Pi Compute Module 4 IO Board

But it is possible to connect to a 10 gigabit network at 10GBase-T speeds using a Raspberry Pi Compute Module 4 and an appropriate PCI Express 10G NIC. And on my Pi PCI Express site, I documented exactly how I got an ASUS XG-C100C working on the Raspberry Pi. All it takes is a quick recompile of the kernel, and away it goes!

The Raspberry Pi IoT Notification Bell

Harbinger of the Internet of Dings

Last year, I built the first version of what I call the "Raspberry Pi Bell Slapper." It was named that because it used a servo and a metal arm to slap the top of the bell in response to a stimuli—in this case, an email from a donation notification system for a local non-profit radio station.

This year, that same radio station had another one of their fund-raisers (a radiothon), and to celebrate, I thought I'd do the thing justice, with a better circuit (using a solenoid instead of a servo) and a 3D printed enclosure. And this is the result:

Clarence 2.0 - The Raspberry Pi Notification Bell

There is a Raspberry Pi Zero W with a custom solenoid control HAT on top inside the case to the left, and the solenoid right up against the bell, which is mounted on the right.

I also posted a video on YouTube exploring the project in detail: The Raspberry Pi IoT Notification Bell.

Monitor your Internet with a Raspberry Pi

Internet Service Providers are almost universally despised. They've pushed for the FCC to continue defining 25 Mbps as "high use" broadband, and on top of that they overstate the quality of service they provide. A recently-released map of broadband availability in the US paints a pretty dire picture:

USA map showing areas with limited high speed broadband availability

Here in St. Louis—where I guess I should count my lucky stars we have 'high use' broadband available—I have only two options: I can get 'gigabit' cable Internet from Spectrum, or 75 megabit DSL from AT&T.

That's it.

And you're probably thinking, "Gigabit Internet is great, stop complaining!"