Category Archives: Scribbles

Don’t buy garbage

I often hear expectations on what electronics “should” cost being set based on the cheapest price available on Ebay, Aliexpress et al.  Everybody loves a bargain, but the old saying “you get what you pay for” is just as true as ever.  What worries me is that by paying for junk, rather than quality, consumers are voting with their wallets for an inferior technological future.

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Taming the rPi Touchscreen PCB

After my last article‘s mission of discovery I set about trying to stop the rPi Official 7″ Touchscreen from interfering with my 2-way radio.  It looked like the LCD ribbon cable was broadcasting spurs every ~1MHz or so right through the VHF range.  I acquired some adhesive copper tape thinking I could shield the cable to prevent the noise from escaping.

The copper tape arrived, and despite wrapping the LCD ribbon cable and grounding the copper tape it failed to provide any shielding benefit.  Nuts.  So what else can I try?

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RPi SD Card corruption, a new kernel, device trees and a lesson learned

I recently fell victim to the perils of my own laziness.  Rather than gracefully shut down my Raspberry Pi in order to move it, I pulled the power cord.   I had done this dozens of times in the past with no ill-effects but today was my unlucky day.  The Pi did not come back!

Unfortunately, this snowballed from a simple file corruption issue into a full reinstall, which ended up using a different kernel version that broke my custom 1-wire bus setup.  Great.

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Fixing Random Electronics

Last Xmas I bought myself a quadcopter, and have had fun flying it.  Unfortunately after an “attack of dog” (a friend’s dog was trying to be helpful by retrieving the quad any time it landed) one of the motor wires broke.  Rejoining the wire was a snap, but the quad did not turn on.  It just gave a brief flash of its LED before switching off again.

I had a close look at the main board and found a generally shoddy soldering job – look for the upside down resistor!  One of the components was also missing (blacked out in the picture).  So how to identify and replace this mystery component?

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Hello World


Computers should be easy, right?  Well, providing someone behind the scenes is doing the grunt work, they are.  Most people are unaware of the level of complexity under the surface.  As an embedded engineer I am closer to the metal than most. I’ve made a living out of turning diodes, resistors, capacitors and microcontrollers into something useful.  Nothing is terribly useful in isolation, so you invariably want to communicate with it.  That needs computer software; I do that too.  All of this takes hours.  Hours and hours and hours.  Then, once it works as intended (a stage I call barely working), it needs to be tested in a way NOT intended.  Let’s face it, the first thing somebody is going to do is type in the wrong thing, connect the wrong wire, or connect the power backwards and blow it up.  Manuals are only consulted under a cloud of blue-grey smoke (that’s the magic smoke inside the chips, it’s surprisingly expensive to put back in and this upsets most people).

Of course, in the customer’s eyes they can do no wrong.  What separates an average engineer from a good one (in my opinion) is the good one tries to break his creation as soon as he’s made it. Reliability is a cornerstone of good engineering, and a device that only works when all the stars and planets align, and people use it as the designer intended, is going to take around 5 minutes on average to fall over.

The problem with consumerism is people want things yesterday, and they want it cheap.  They will buy the gadget that has been rushed to market and released barely working and then have an experience like the xkcd comic above.  The challenge is to find the happy medium, where barely working becomes good enough and then everybody wins.  After good enough you get almost perfect and this is an excellent device that has been well-developed but took its time getting to market.  It usually costs more and this is my favourite type of device because it works brilliantly.  However, it seems most people shop primarily on price and few are willing to pay a premium for something amazing.  This is unfortunate as excellence is what drives us forwards and it is important to seek it out.  We didn’t land on the moon by being average.


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