Raspberry Pi 4

I know it’s been a while since I’ve posted, but I’m still working on Raspberry Pi (and Raspberry Pi related projects). My latest project is Dive into Systems, a free on-line textbook for introductory computer systems concepts that I co-author with Swarthmore professors Tia Newhall and Kevin Webb. You can learn more about it here: http://www.diveintosystems.cs.swarthmore.edu

Of course, the other bit of news is that the Raspberry Pi 4 was released earlier this summer, and it not only boasts gigabit Ethernet, but configurations that support up to 4 GB of memory. I managed to get my hands on one of them, and I have to say, I’ve been having a LOT more difficulty with this version than previous Raspberry Pis.

Getting the monitor working (HDMI out of range error)

My first challenge was getting it to work with my older HDMI portable monitor, which has worked great with previous Raspberry Pi models without any issue. However, I got an “HDMI out of range” error when I tried to boot with the Raspberry Pi 4, regardless of what image I chose to use. Very frustrating, since one of the key selling points of the Raspberry Pi is its “work out of the box” capability.

I was able to fix the issue. If you run into something similar, start by inserting your microSD card into your computer and navigating to the /boot partition. The file you are typically looking for is /boot/config.txt. Please note that this is completely different from the /rootfs/boot directory, which is located on a separate partition (it will likely mount as two separate drives on a Desktop computer). If you don’t see a config.txt file, it is likely that you are looking in the wrong partition.

Next, modify the /boot/config.txt file to include the following lines:

hdmi_force_hotplug=1
hdmi_drive=2
hdmi_safe=1

Save the file, reinsert into your Raspberry Pi 4 and commence rebooting. You should now be able to see the desktop, and continue Raspberry Pi configuration as per normal.

Note: in some distros (e.g. Ubuntu IOT), the file you want to edit is /boot/usercfg.txt, NOT /boot/config.txt. In these cases, the config.txt file will warn you not to edit it directly, and point you to the file that should be edited instead.

Heat Issues

The next thing I noticed was that the Raspberry Pi 4 runs HOT. This is not an OS issue; the temperature of a Raspberry Pi 3B+ running the new Raspbian Buster OS stays consistent at around 75 degrees when doing sudo apt get update && apt-get upgrade. In contrast, the Raspberry Pi 4 running Buster runs significantly hotter, with the SDRAM chip reaching temperatures of 116 degrees.

Thankfully, a new firmware update has been made available that will fixes many of the issues. After running sudo apt-get update && apt-get upgrade, run the following two commands:

sudo apt-install rpi-eeprom rpi-eeprom-images
sudo reboot

Tom’s Hardware has a nice article explaining the issue in detail and how the firmware updates fix it.

Comparing different images for the Raspberry Pi 4

Raspbian Buster is (at the time of writing) the newest Raspbian release from the Raspberry Pi foundation. It will likely work well for most applications. Note that this is a 32-bit OS, like previous versions of Raspbian. If you want a 64-bit OS, you will need to do a bit more searching.

I also tried Ubuntu Server IOT for the Raspberry Pi 4. This has 64-bit support; However, the image is very bare bones, and does not include many of the basic networking tools by default. Therefore, you will need a working Ethernet connection to complete setup. However, the 64-bit core release is still in beta, and the USB ports don’t seem to work for the 4GB version. Ubuntu recommends adding the following line in /boot/firmware/usercfg.txt for 4GB models:

total_mem=3072

This limits the memory on the 4GB model to 3GB. Again, this should not be an issue for the 1GB and 2GB models. Some channels are reporting that while Canonical plans to extend full desktop support to the Raspberry Pi 4, it may be a while yet; the immediate focus will be Ubuntu Core.