Phillip Pearson - web + electronics notes

tech notes and web hackery from a new zealander who was vaguely useful on the web back in 2002 (see: python community server, the blogging ecosystem, the new zealand coffee review, the internet topic exchange).



Here's another couple of CPU possibilities: one from Atmel, and one from Microchip:

First, the South Island Component Centre stocks a bunch of Atmel CPUs, including the $4.77 ATTINY12-8PI, an 8MHz 8-pin micro with 1kB of flash and 6 I/O pins. You can program these with an Atmel port of GCC if you don't like their assembly language.

Second, from Microchip, I can get the PIC12F629 chip, in the guise of the PICAXE-08. Also the 12F675 is available. The cool thing about the PICAXE-08 is that it has an ultra-cheap prototype board to make playing around easier. CPU + board = $15 incl GST. It might need a $10 download cable too. The disadvantage is that it only has 128 bytes of program memory, so only really small programs will fit.

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Home automation notes

The PIC16F628 seriously fails to suck. All the features of the 16F84 and then some, and US$1.80 each for 25+ at Digikey. By the time a batch of 25 would make it to New Zealand, that's about NZ$5 each. I may be out of date, but this seems about 20-50% of the cost of comparable AVR chips. They don't look as efficient or easy to program as the AVRs, though. [The AVRs execute one instruction per clock, and I built a parallel cable to program them a while back that only needed two transistors.]

OpenPic.Net is a complete DIY home automation system that uses the 16F84 (or 16F628). It's controlled by a PC, and uses a star-connected serial bus for communications (very simple protocol, at about 500 bps).

Now what I need is a slightly safer / better equivalent of the OpenPic.Net switched power plug. I don't like the look of the solid-state relays they're using; I'd prefer an optocoupled magnetic relay, to make things less catastropic in case of a fault and to allow switching beefier devices.

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Camera choices

Just before Christmas, I managed to destroy my Casio Exilim EX-S2 camera. The repair will cost either about $150 or about $600, depending whether the main circuit board is screwed or not. I'm not sure if I want to risk the latter bill, so I've been cameraless for the past few months.

Now I'm looking for a replacement. Here are the choices so far:

  1. another EX-S2 (off eBay; 2MP; small) - about NZ$300
  2. an EX-S3 (new; 3MP; small) - NZ$580
  3. an EX-Z3 (new; 3MP; optical zoom) - NZ$650
  4. a Pentax Optio S (new; 3MP; optical zoom; smaller than EX-Z3) - NZ$700

I can't decide whether I want to go for another small/slim camera (EX-S2 or EX-S3), or for something with optical zoom (EX-Z3 or Optio S). My father has an Optio S, and it looks good, but it's quite big compared to my old EX-S2. The EX-S2 permanently lived in my shirt pocket, so it was always there when I wanted to take a picture, but I'm not sure if I could do that with either of the EX-Z3 or the Optio S.

(Note: NZ$1 is about US$0.50-0.70, depending).

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