The FDT file for Raspberry Pi, declares UART. I’ve had quite a bit of trouble understanding how declaring a uart in the FDT results in /dev/tty0 and /dev/cuau0 appearing in /dev/ Here are the relevant lines from the FDT: uart0: uart0 { compatible = “broadcom,bcm2835-uart”, “broadcom,bcm2708-uart”, “arm,pl011”, “arm,primecell”; reg = <0x201000 0x1000>; interrupts = <65>;…
Recently I found myself wanting to understand how I2C for FreeBSD ARM, on the Pi works. The first step is to understand the GPIO implementation on Pi, since on a Pi, I2C is implemented on the GPIO. So, here’s the basic summary. Firstly, the FreeBSD source browser is here. In the directory /sys/ is the…
The FDT is the “Flattened Device Tree”, a simple device tree used in embedded FreeBSD, for example on a Pi. Every architecture has a DTS file, which contains a human-readable list of hardware for that architecture. For example, the Pi FTD is here. You should notice that there are declarations for: cpu axi (the…
I recently found myself in a situation where mission-critical software was suffering from performance problems due to relying on a remote API which was both slow (as slow as 11sec / transaction), and unreliable. In this case, it turned out that there were multiple applications accessing this API, and every individual application was affected….
One of the best things about the Pi is that it’s small, and portable. It’s very tempting to use it on wireless networks, unattended. Sadly, in the real world, any wireless network can be hacked, and any device on wireless should be considered vulnerable. So, pf is an easy way to harden your Pi. The…
I’ve been building FreeBSD-CURRENT images for my Pi, and I’ve noticed I have this: ugen0.5: <vendor 0x7392> at usbus0 So, it turns out I have one of these plugged in, and it seems likely that the unknown USB device is ugen0.5. So firstly, there is the question of “ugen”. You can read about it here….
The default FreeBSD kernel for Raspberry Pi can be found here in the FreeBSD source browser. It’s everything you need to boot FreeBSD on a Pi, and includes GPIO support. However, the Pi is a nice small computer, so it’s likely that you’ll want it to include options such as Wifi, and pf. In my…
I’ve been making FreeBSD-Current builds for my Raspberry Pi. Naturally I wanted to try out the GPIO support to find out just how simple it is to use. Here’s an example, and the full code is here. int main (int argc, char *argv[]) { char *device = “/dev/gpioc0”; int gpiofd = open(device, O_RDWR); if…
I’ve had the opportunity to make some updates to the freebsd-arm-tools. If you’re interested in trying FreeBSD-current on a Raspberry Pi, I’ve posted a build at http://files.khubla.com/freebsd-raspberry-pi/ which has full Wifi and pf support. If you’re interested, the kernel configuration is here. Installing the FreeBSD on the Pi is simple. Firstly, get an image, such…