Thursday, July 30, 2009
I was aimlessly Googling about today when I came across... No, let me rephrase that - when I encountered the phrase "crotchless chastity belt"...
Now is it me, or is someone seriously missing the point there? Or is someone getting the point when they shouldn't? Either way the phrase "crotchless chastity belt" has replaced "chocolate teapot" in my vocabulary...
I was working with a chip today, doesn't really matter what it was, when I realised that we are well and truly into the aftermath of the n'th industrial revolution. It's over, bar the shouting.
What shows this is the number of designs I now see that are fundamentally flawed, and flawed in ways that show the designers really don't know what they are doing. They get the basics wrong. I think the problem is that the leaders of the silicon revolution, or whatever fancy phrase you want to use to describe it, are now dying off and their hard-earned knowledge is being lost - the problem is that the good guys were all too busy doing it, whatever their particular "it" was, to write about how they did it, and they are now being replaced by people who have not learned from the ground up but rather were taught complicated subjects by those who weren't all that competent in the first place...
Up to the biotechnology people to take up the baton now, I guess.
Tuesday, July 28, 2009
Monday, July 20, 2009
Someone asked me recently what aspect of my time in the games industry I remember most fondly. My knee-jerk answer to this sort of question is "Halls" but for a change I thought about it and there really is only one thing (aside from Halls) that still amuses me every time I come across it, and it is this couple of sentences that Psi and I wrote for the story line of Dr Strangefruit:
Strangefruit removed a dog-eared, loose-leaf notebook from an inside pocket and placed it reluctantly on the desk, as if parting with an art treasure of great value. Pratt reached over and picked it up, holding it by one corner, as one might retrieve a piece of used toilet-paper that had missed the bowl. It was not in keeping with Pratt's idea of documentation and did not appear to merit being on such an executive desk. "Might I ask what this is about ?" asked Pratt, who didn't want to have to read it to find out.
Well, there you go. More fun contained in a single paragraph than some of my complete games. We don't write 'em like that any more...
Tuesday, July 07, 2009
So, today I'm working on a new industrial input card for our logger family. Lots of 0..20mA inputs and some switched outputs, usual sort of stuff.
For added interest it has two AVR processors. A Mega128 sitting down near ground doing most of the work (handling the comms, multplexing inputs, driving the ADC and so on) and a Mega8 sitting up near the supply positive rail watching the current drawn on the outputs and turning them off if the current exceeds preset limits. These two talk to each other through a level shifting serial link.
Doing it with two processors is both the cheapest and neatest solution to the problem, the alternative would be to have lots of level shifting hardware for the various outputs and current sensing lines, which would involve much more hardware and be less accurate with it.
But - there had to be a but - it does mean that I have to simultaneously develop software for two processors that are running at different grounds, and also one of them needs a software emulated serial port because the hardware ones are busy doing other comms jobs, hence there is some slightly awkward software and the programming requires isolated AVR programming/debugging interfaces. Well, I have those, so no problem.
Hah. The gods don't like cunning designs.
I blow the first Mega8 up when the bloody ground clip of a 'scope probe unclips itself and wanders across the PCB, managing to touch one of the AVR I/O pins. Normally this wouldn't be a problem, but it picks the AVR that has its ground up at +20V or so. It doesn't like having one of its pins dragged down to -20V (as it sees things) so bye-bye and off to silicon heaven it goes.
Much gallic muttering ensues as Herve replaces it.
A few hours later I'm busy working on the serial comms between the two processors when the 'scope probe slips out of my hand. It misses the board and I have a moment of relief until I realise it's heading for the exposed PCB of the isolated AVR programmer... It lands on it and there is a very slight, but clearly audible, click as the earthed shield of the probe makes contact with some component or other on the programmer.
Of course, it doesn't do this with the programmer that's sitting at ground, it picked the programmer that was connected to the positive rail and which was sitting with its ground at +20V or so, and that click signifies the end of that particular programmer. And, of course, the end of the bloody AVR it was connected to as well.
This happened at 10:30 pm, and at about 11:30 pm there was even more gallic muttering as Herve (dragged back into work) replaced the Mega8 again. This was accompanied by a fair bit of my own muttering as I repaired the AVR programmer.
About an hour and a half later the other AVR, which had been sitting down at ground and minding its own business, stopped talking to the debugger. After a bit of investigation it turned out that one of its I/O pins was damaged at some point in the preceeding fiasco and had quietly rotted.
Think I'll wait 'till tomorrow before I tell Herve he's got to replace the Mega128 now.
I'm starting to think the gods really don't like this design...