raspberry pi

tl;dr: The Raspberry Pi Pico is a new $4 microcontroller board with a custom new dual-core 133 MHz ARM Cortex-M0+ microprocessor, 2MB of built-in flash memory, 26 GPIO pins, an assortment of SPI, I2C, UART, ADC, PWM, and PIO channels.

It also has a few other party tricks, like edge castellations that make it easier to solder the Pico to other boards.

The Pico is powered by a new RP2040 chip—a brand new Raspberry-Pi-built ARM processor. And the best thing about this processor is the insanely-detailed Datasheet available on the Pico website that steps through every bit of the chip's architecture.

Video Review and 'Baby Safe Temperature' Project

I posted an entire video reviewing the Pico and demonstrating a MicroPython project. The video is embedded below:

I didn't know it at the time, but my results testing the EDUP WiFi 6 card (which uses the Intel AX200 chipset) on the Raspberry Pi in December weren't accurate.

It doesn't get 1.34 gigabits of bandwidth with the Raspberry Pi Compute Module 4 like I stated in my December video, WiFi 6 on the Raspberry Pi CM4 makes it Fly!.

I'm very thorough in my benchmarking, and if there's ever a weird anomaly, I try everything I can to prove or disprove the result before sharing it with anyone.

In this case, since I was chomping at the bit to move on to testing a Rosewill 2.5 gigabit Ethernet card, I didn't spend as much time as I should have re-verifying my results.

I got this Rosewill RC-20001 PCIe 2.5 Gbps Network Adapter working on the Raspberry Pi Compute Module 4.

Right after I got the card working, though, I tested it in an external powered PCI Express riser, and that test released the card's magic smoke. Oops.

Here's a dramatic re-enactment that's actually pretty accurate to what it looked like in real life:

Luckily, buying a replacment wasn't too bad, since the card is less than $20. But to get it to work on my spiffy new ten gigabit network, I also had to buy a new SFP+ transceiver that was compatible with 1, 2.5, 5, and 10 Gbps data rates, and that cost $60!

Raspberry Pi OS isn't really built to be a server OS; the main goals are stability and support for educational content. But that doesn't mean people like me don't use and abuse it to do just about anything.

In my case, I've been doing a lot of network testing lately—first with an Intel I340-T4 PCIe interface for 4.15 Gbps of networking, and more recently (yesterday, in fact!) with a Rosewill 2.5 GbE PCIe NIC.

And since the Pi's BCM2711 SoC is somewhat limited, it can't seem to pump through many Gbps of bandwidth without hitting IRQ limits, and queueing up packets.

In the case of the 2.5G NIC, I was seeing it max out around 1.92 Gpbs, and I just wouldn't accept that (at least not for a raw benchmark). Running atop, I noticed that during testing, the IRQ interrupts would max out at 99% on one CPU core—and it seems like it may be impossible to distribute interrupts across all four cores on the BCM2711.

January 1, 2021 Update: My 1.34 Gbps benchmark was flawed. See this GitHub issue and this updated blog post to learn more: WiFi 6 is not faster than Ethernet on the Raspberry Pi.

After buying three wireless cards, a new WiFi router, optimizing my process for cross-compiling the Linux kernel for the Raspberry Pi, installing Intel's WiFi firmware, and patching Intel's wireless driver to make it work on the Raspberry Pi, I benchmarked the EDUP Intel AX200 WiFi 6 PCIe card and got 1.34 Gbps of bandwidth between the Raspberry Pi and a new ASUS WiFi 6 router.

This is my story.

Last year, I wrote a blog post titled The Raspberry Pi 4 needs a fan.

And in a video to go along with that post, I detailed the process of drilling out a hole in the top of the official Pi 4 case and installing a 5v fan inside.

But that solution wasn't great. The fan was a little loud and annoying, and would stay on constantly. And who wants to damage the nice-looking Pi Case by putting a hole right in the top?

Since the day I received a pre-production Raspberry Pi Compute Module 4 and IO Board, I've been testing a variety of PCI Express cards with the Pi, and documenting everything I've learned.

The first card I tested after completing my initial review was the IO Crest 4-port SATA card pictured with my homegrown Pi NAS setup below:

But it's been a long time testing, as I wanted to get a feel for how the Raspberry Pi handled a variety of storage situations, including single hard drives and SSD and RAID arrays built with mdadm.

I also wanted to measure thermal performance and energy efficiency, since the end goal is to build a compact Raspberry-Pi based NAS that is competitive with any other budget NAS on the market.

There are many Raspberry Pi projects where I spend a few hours (or dozens of hours) building something with a Pi, and realize at the end that not only could I have purchased an off-the-shelf product to do the same thing for half the component cost, but it would work better too.

But this is not one of those projects:

The Raspberry Pi and its HQ camera make a surprisingly potent webcam, and if you want to cover the basics, and rival the image quality of all but the highest-end dedicated webcams, you can do it for under $100.

Above is a single frame from a recording I did with the HQ Camera on my Raspberry Pi Zero W connected as a standard USB webcam using the Camera app on Windows 10 on my Dell laptop.

Out of the box, to conserve power, the new Raspberry Pi Compute Module 4 doesn't enable its built-in USB 2.0 ports.

You might notice that if you plug something into one of the USB 2 ports on the IO Board and don't see it using lsusb -t. In fact, you see nothing, by default, if you run lsusb -t.

To enable the USB 2.0 ports on the Compute Module 4, you need to edit the boot config file (/boot/config.txt) and add:

dtoverlay=dwc2,dr_mode=host

Then reboot the Pi. Now you should be able to use the built-in USB 2.0 ports!

After doing a video testing different external GPUs on a Raspberry Pi last week, I realized two things:

1. Compiling the Linux kernel on a Raspberry Pi is slow. It took 54 minutes, and I ended up doing it 7 times during the course of testing for that video.
2. If you ever want to figure out a better way to do something, write a blog post or create a video showing the less optimal way of doing it.

To the second point, about every fifth comment was telling me to cross-compile Linux on a faster machine instead of doing it on the Pi itself. For example:

And on the Pi Forums, it seems like nobody worth their salt compiles the kernel on the Pi either, so I figured—since I'm probably going to have to do it again another thousand times in my life—I might as well put together a guide for how to do it on a Mac.