Computing stuff tied to the physical world

More re-design needed

In Hardware on Sep 21, 2009 at 00:01

This is embarrassing…

It looks like some trivial plugs in Plug Panel 1 do work, but everything of even the slightest complexity (and usefulness) is faulty :(

The Expander Plug has a completely incorrect pin allocation for the MCP23008 18-SOIC chip. Which I had to create from scratch in EAGLE, and obviously I’m still learning just how to do that. Lesson one: don’t move pins in a package around without checking their pin numbers afterwards!

Unfortunately, that means the LCD Plug I sent off a few days ago will also come back useless :(

The Thermo Plug can’t turn off its buzzer because a trace is shorted out to a pad (I guess I didn’t do a DRC), and the thermocouple interface isn’t working because the AD597 chip needs at least 5V as power supply. So much for sensing or controlling anything. Oh well, I suppose the NTC and 1-wire inputs work.

The Room Plug didn’t work with a 1-wire DS18B20 sensor, in fact it looks as if the 1-wire sensor is hooked up the wrong way around since it’s shorting out the 3.3V supply. And the EPIR sensor isn’t responding either. I haven’t tried other configurations yet.

The Clock Plug mistake was described yesterday. It’ll probably work with a DS1340 chip i.s.o. a DS1307.

The I2C Connector … well, ehm, I mixed up the AIO and DIO pins. Incredible stupidity.

Oh, yes, there is some good news – the Breadboard Connector “works”:


But then again, it’s a bit hard to mess up a tiny pcb with no electrical components on it :)

Drat. Back to the drawing board. I may need several iterations to get my act together. This will add weeks to the process. Of course it’s a learning experience, such as: lesson 2 – check and double-check, and lesson 3 – check everything again. E v e r y t h i n g !

Man, do I feel JeeSilly right now…

  1. That’s what prototypes are for! Thanks for putting all the effort and resources in it! I got my jeenode boards. I’ve got them half assembled, waiting on the radios from china and I can’t find female header recepticle at a reasonable price at a US distributor. I’m excited though!

  2. Ahh, this explains why I couldn’t get the DS18B20 sensor to work on Room Plug wiring. But now I figured out how to connect it. I will write more in the forum.

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