automating, building and graphing the world


[*** Look at the Rabbit section for an update on the Basic Stamp and Ethernet. Originally the only available product to add ethernet to a Basic stamp was an expensive $75 and only left 1 pin for your projects. - The Rabbit is $55 in quantities of 1 but is much more powerful, especially if you just use serial i/o to communicate with the Rabbit ***]

The first project was designed so that I could get used to the Basic Stamp and the electronics behind it. I have to own up here and now that I have little or no electronics experience or knowledge..Which really goes to show how good this Basic Stamp stuff is!!

The first part of the project was to get some data (temperature readings) out of the DS1620. All very easy if you read the notes in the (free, downloadable) book "Stampworks", it's also available as a 'real' book if you want.

MM74HC165 - Parallel-in/Serial-out 8 bit shift register
DIP switches
433 Mhz Tranceiver

Next Steps... I really want to get these devices working over ethernet but want to maintain the flexability of the wireless(ness) of this version.. Let me use a real world example to explain what I'm thinking:

You want to measure the temperature in your greenhouse.
You don't have CAT5 available in the greenhouse.

What do you do?

Simple on 433Mhz temperature monitor in the greenhouse which 'talks' to the receiver in the house. The receiver, as well as having a 433Mhz transceiver has a CAT5 interface which is plugged into you network.

Essentially we are talking about 2 types of temperature monitor:

Direct network connection via CAT5 (ideal).
Wireless monitor to receiver with CAT5 Interface.

You wouldn't need a receiver with CAT5 interface for all of your units because the DIP switches allow for up to 255 wireless 'nodes', the only limiting factor might be the range. The CAT5 interface modules will need to utilise the 40 pin versions of the BS2p Stamp because of the extra input/output pins required for the network interface. Currently on a standard 24 pin BS2p I'm using 7 of the 15 available... the ethernet module requires 14 of the 15 to work. I'd also like to utilise some form of storage for the final module to store information like the IP address, MAC address and, say, the last 20 readings. The BS24p allows you to store data in other program slots (2k per slot 8 slots in all) so this is more than enough to hold the information required.. The BS24p is more expensive though :-(

There is also a BS40p with 16 extra i/o pins which means that the entire project is perfectly feasable, if a little more expensive...

Ethernet Controlled AV Switcher
The ASEL ( ) Audio and video switchers work extremely well. Theses ASEL boards come in two flavours, the 16 input 2 output Video or the eight input 2 output stereo audio. The boards are identical except for the ROMs so one hardware device should be able to interface with either incarnation. The advantage of these boards is that not only do they respond to serial commands to select the inputs/outputs, but they can be daisy chained off each other. What this means is that you can en up with an eight port stereo audio AND video switcher with another eight ports of video only.

Simplicity itself with a BASIC stamp controlling it! A little harder with ethernet ;-)
At What Cost?
Practically speaking this method of implementaton is far too expensive to implement on a house-wide scale. The ethernet module alone costs $75 (about 45 GBP) and RF tranceivers are around $119 (around 71 GBP). You're not going to get much change out of 160 GBP for each project and that doesn't include things like the ASEL boards (for the AV Switch).