yo holmes: Archive

Bob Pease is not just an electrical engineer

He is definitely also a magician

Apr 19th

Feb 4th

Linux Device Drivers, 3rd Edition (it's free!) →

Oct 26th

Oct 22nd

USB host on android

Attaching a broadcast receiver at runtime for the USB_DEVICE_ATTACHED event doesn’t work in 4.1.2. See here. Intent filter method works but has a deadlock bug in the usb subsystem. Lovely.

Oct 16th

ADS1118 problem solving

1. If you continuously update the configuration register and read it at the same time, the device will lock up. 2. Make sure you are using SPI with negative edge stable polarity 3. It takes about 3ms to switch the mux between channels; it will only switch after all of the pending conversions are complete What is it? one of these.

Oct 16th

Prior HK101 motorised microscope stage pinout

DB25 connector: 1 - first coil in x stepper, A+ 2 - second coil in x stepper, B+ 3 - limit switch 1 for x axis (NC) 4 - limit switch 2 for x axis (NC) 5 - first coil in y stepper, A+ 6 - second coil in y stepper, B+ 7 - limit switch common for y axis 14 - first coil in x stepper, A- 15 - second coil in x stepper, B- 16 - limit switch common for x axis 17 - first coil in y stepper, A- ...

Aug 1st

Jul 27th

“Three weeks in the lab will save you a day in the library every time”

– R. Stanley Williams

Jul 23rd

NASA research on lead-free solder →

One interesting point: lead can only enter the body by inhalation (it boils at ~1700C) and by ingestion.

Jul 23rd

“Probes are vital to oscilloscope measurements. To understand how vital,...”

– Tektronix Probe Fundamentals

Jul 14th

“In this world, Elwood, you must be oh-so-smart or oh-so-pleasant. Well, for...”

– From the play Harvey

Jul 11th

Pandora is live in Australia! →

Been waiting a long, long time for this

Jul 10th

South: schema migrations for Django →

Pretty sure this should be built in, but I suppose they have their reasons.

Jul 9th

Jun 29th

The innocuous 'inline' keyword →

Some love it, some hate it. I personally think it is useful, but one must always be careful with these sorts of compiler features.

Jun 20th

Xilinx and Digilent release a low cost Zynq kit →

Exciting stuff! The Zynq is a dual core ARM A8 merged with an FPGA. This is the way general purpose CPUs will go once we hit the point of diminishing returns for the number of cores. Also, PetaLogix builds the Linux gear for it; UQ represent!

Jun 18th

walter lives →

hey overdetermined RLC equations, take this!

Jun 16th

DSA815-TG: 1.5GHz spectrum analyser with tracking... →

Oh Rigol, why you make so many things I want ?

Jun 14th

STM32F0: actually, they are pretty neat

80uA per MHz? Even my grandmother can run a micro with that

Jun 11th

iOS development: pretty cool

Although I do not enjoy wearing out my square bracket keys, Apple definitely have this UI stuff down.

Jun 8th

note to self

when using GCC to do all-in-one linking, the order of library flags matters.

Nov 29th

STM32F4 compiling under linux (with hardfloat!)

Get a patched version of summon-arm-toolchain clone https://github.com/jeremyherbert/stm32-templates cd to the “stm32f4-discovery” folder run make enjoy hardware floating point support To add hardfloat support to your own projects, use the compiler flags: -mcpu=cortex-m4 -mthumb-interwork -mfloat-abi=hard -mfpu=fpv4-sp-d16

Nov 29th

STM32VL Discovery experiments

Picked this board up a while back and decided to start playing with it. They do *not* make it easy to use open source tools (or provide decent documentation).

Oct 28th

FPGAs are really cool

it’s so refreshing to do digital signalling without having to use interrupts.

Sep 23rd

Jul 16th

May 20th

May 1st

interrupts are not to be messed with

I came across an interesting bug while working with one of my students today. His AVR would continuously reset unless interrupts were switched off, but he needed them on for his project. This might seem pretty baffling (it was to me for a few minutes), but if you sit down and think about the code from an assembly perspective it should be obvious what was going on. Try and work it out! ...

Apr 3rd

laser-related epiphany

just realised how the optics in a laser cutter works. Laser tube is mounted parallel to the gantry/gantry rail attachments with 3 mirrors: one 45 degree which redirects the beam from the laser tube down the gantry rail, one 45 degree on the gantry which redirects the beam across the gantry and one rotated 45 degrees down the z axis to redirect the beam into the material to be cut. bloody sickness...

Mar 10th

sick, in bed

time to give my kindle a proper run through

Mar 10th

just put an SSD in my macbook

Not buying another computer without an SSD. The performance boost is ridiculous.

Feb 25th

Feb 20th

Feb 18th

Feb 17th

a fun trick to play on your friendly sysadmin/user

find a video on youtube you know they will recognise use your favourite youtube downloading mechanism (I used catchvideo) put the flv somewhere you know append the following to their .bashrc: resize -s 60 170 ; mplayer -vo caca -framedrop -quiet -really-quiet -loop 0 /home/bob/video.flv wait for them to log in with putty enjoy keep on truckin’ jozza

Feb 15th