Light field stereoscope VR headset

Moving away from traditional stereoscopic 3D for VR headsets (such as the Oculus VR devices) is all the rage now. Microsoft’s HoloLens and Magic Leap‘s upcoming headset are part of this new wave but details of the underlying technology are virtually non-existent. However, a group from Stanford are presenting a paper on their light field stereoscope at SIGGRAPH2015 in Los Angeles next month that describes how the light field technology works. Worth reading if you want to know more about this emerging tech.

Incidentally, I first went to SIGGRAPH in Dallas in 1981. Quite a bit has changed since then!

Changing the Raspberry Pi/Pi2 I2C bus speed, device tree style

Pi2v1Recent releases of Raspbian have started to use the device tree which has the effect of altering the procedure for controlling the I2C bus speed (amongst other things). The new procedure involves a device tree overlay or device tree parameter. These instructions have been distilled from this page.

On the latest Raspbian releases, the required overrides are already present. All that’s needed is to set a device tree parameter. To do this, edit /boot/config.txt and add the line:


Reboot and then you should see a message ( or use the dmesg command) indicating that the I2C speed is indeed 400000. If the release is older, a device tree overlay is needed to add the overrides.

Continue reading “Changing the Raspberry Pi/Pi2 I2C bus speed, device tree style”

Using the Raspberry Pi’s serial port

DB-25Yes, that is a DB-25 plug I found in a box of old stuff. Anyway, I wanted to connect a GPS via a serial interface to a Raspberry Pi. Somehow it had escaped my attention that there is a handy serial port available on the Pi’s connector – I had been wondering what /dev/ttyAMA0 was!

Continue reading “Using the Raspberry Pi’s serial port”

The end of the (phone) line

PhonesThey were just sort of there, a legacy from a past barely remembered. If only they had just sat there quietly they probably would have been allowed to hang around collecting dust for ever. But no. The scam artists, scumbags, political organizations (also scumbags), the IRS (not really, just more scam artists) etc that kept calling made them a target for the axe. Comcast only allows 25 blocked numbers – that’s nowhere near enough! Now relegated to a plastic bin, they join all kinds of other archaic objects in the basement such as big desktop PCs, Blackberries and VGA monitor cables.

So long phones – your annoying and pointless rings will not be remembered fondly.

Avoiding USB serial port permissions problems on Ubuntu

One of the most annoying things about Ubuntu (and Linux in general) is that USB serial ports can only be accessed in superuser mode unless something is done. The result is that you can see the port as /dev/ttyXXXX but can’t open it. While there are other ways, adding your user name to the dialout group will usually fix this:

sudo adduser <username> dialout

Then log out and log in again to kick in the new setting.