project design

Hi, I am a hobbyist that came up with a cool idea for saltwater fishtanks; however, this idea calls for the use of an electronic control system. I went to college for ~7mo. for electronics, but never completed my training and I just possess minimal knowledge on the subject. However I've been doing alot of research on this, and I've got some ideas on what I'll need. I figured I would run them by this group and see if I can get my questions answered.

First off, view a rough design of the control box:

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The delay and tubes will be set with a 12position and 7position rotary switch respectively. The rotator will be a small switch and the feed will be a push button. This control box will drive a stepper motor (probably bipolar) and will have a position sensor on the main drive. (Is this needed?)


inputs: (22?) 12 for delay rotary switch, 7 for tubes rotarty switch, 1 for rotator switch, 1 for feeder push button, and 1 for the sensor located on the rotator

outputs: (?) 1 for status LEDs, 1 for relay to pump receptacle, and 4??? for the stepper drive control?

Basically what I want this unit to do at startup is rotate the rotor until the position sensor is aligned at point "0", then it will launch into its regular program. This program will check how many tubes are used, and which rotator model is installed. From that it will determine how to move the rotator to make use of this configuration. After movement it will check the delay and pause for this amount of time (3-15 seconds) Then it will move again and repeat. After the first pass it will turn on the relay that enables the pump recepticle to become energized and turn on the green status LED.

When the feed push button is depressed I want the unit to go into a hibernation mode. This mode will turn the red status LED on, and turn the green one off. It will also reset the relay to the pump recepticle to turn this external unit off. I want the unit to then pause for 5 minutes and then initiate a restart of the complete system. (Basically like I just flipped the on/off switch off and then back on)

Now according to this picture and information above I have figured I would need a basic stamp II (40 pin variety) as a microcontroller. Is this correct? Will it run this application?

Also is there a way to use a smaller basic stamp with less inputs by some means? Or would any other microcontroller be cheaper or work better for this application. I went back to college and I have a degree in computer programming. So I know BASIC, C, JAVA, and I could probably even learn Assembler if it came right down to it. Like I said this is just a hobby project for me, (since I discovered patents are very, very costly) and I know very little about this. I am willing to find my own way with a little guidance. Thank you -Chris

Reply to
Chris Gentry
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Maybe I'm missing something, but most of your complexity seems to be due to looking after the over-complex system. I can't see what you're doing which is different to a $10 timer (or two?? it's hard to tell from your description) from a fish shop.

On the assumption that there's a deeper meaning I'm missing, then yes, a PIC would very nicely be able handle 20-odd inputs and a few outputs (hell, you could even get clever in the Mk. II version and make it a keyboard and alpha-num display! :-) and this would probably be a nice learning curve. PIC's should be available in your local area for a cheapo price.



Reply to
Ken Taylor

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