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Author Topic: Here's a challenge. I don't know where to start.  (Read 705 times)
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Washington, DC
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I've got a little project I want to start, but I have no idea if it's even possible.

I have three stations (1, 2, 3). Each has three LED lights (a, b, c), and a power outlet. Each station has a button.
-  Power to the outlets at each station is off to start and light a is lit.
-  Button is pressed. Power to outlet is switched on. LED a goes off; c turns on. Power on is timed for 5 minutes. At 2.5 minutes remaining, LED c goes off; b turns on. Power switched back off at time end.
-  Each station can do this without interrupting power to another.
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Grand Blanc, MI, USA
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Plenty possible. What sort of "power outlet" is it, and what might be connected to it?
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Plenty possible. What sort of "power outlet" is it, and what might be connected to it?

A regular 110V power outlet. There is a 10 Watt usb adapter plugged in the outlet. When power is switched on, whatever's plugged in the usb adapter goes on (or whatever's plugged into the outlet).
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The switching circuitry for the 110V would need to be sized for whatever maximum load needs to be switched. If it's just 10W, then a small relay or a solid state switch could do the job. If the intent includes switching large and inductive loads like motors, then that needs to be known and designed for accordingly.

The way I read the description, the three stations are completely independent of each other. So while the three could be implemented with a single controller, each could be a standalone device with its own controller. The smallest microcontrollers (e.g. ATtiny85, less than $2 each) could be used in the latter case. I might favor three standalone devices, as it would reduce wiring and be simple to add additional stations if needed. But I don't understand the total scenario here, the purpose of the project.
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The switching circuitry for the 110V would need to be sized for whatever maximum load needs to be switched. If it's just 10W, then a small relay or a solid state switch could do the job. If the intent includes switching large and inductive loads like motors, then that needs to be known and designed for accordingly.

The way I read the description, the three stations are completely independent of each other. So while the three could be implemented with a single controller, each could be a standalone device with its own controller. The smallest microcontrollers (e.g. ATtiny85, less than $2 each) could be used in the latter case. I might favor three standalone devices, as it would reduce wiring and be simple to add additional stations if needed. But I don't understand the total scenario here, the purpose of the project.

I was a little vague.

Say I have a long table with three stations, each has a 10w power adapter coming from it. Red light on when power is off, green light on when power is on, yellow light on when 1/2 time remains.

The "button" is really a computer input. Could I send a "yes" to station 1 and have it turn on while 2 and 3 remain. Or even better, have the computer handle the timing.

The lights simply indicate the availability of current, "in-use." Is there a way to get a "server" to send the "on" signal to stations independently of each other.
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Grand Blanc, MI, USA
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I was a little vague.

smiley-grin

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Say I have a long table with three stations, each has a 10w power adapter coming from it. Red light on when power is off, green light on when power is on, yellow light on when 1/2 time remains.

The "button" is really a computer input. Could I send a "yes" to station 1 and have it turn on while 2 and 3 remain. Or even better, have the computer handle the timing.

I don't see why not, depending on the computer and assuming appropriate interfaces are available.

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The lights simply indicate the availability of current, "in-use." Is there a way to get a "server" to send the "on" signal to stations independently of each other.

Sure, depending on the definition of "server". Still just a bit vague... smiley-wink
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I don't see why not, depending on the computer and assuming appropriate interfaces are available.

Okay, so let's say there are 30 of these stations. Still possible? Do interfaces exist to do that?

We'd use a Mac to develop this. The Mac would theoretically handle the on/off signals to the stations. It could, say, turn stations 4, 6, 23, and 30 on while leaving the others alone, or any combination therof. Or at least, that's what I'm trying to figure out. I know nothing at all of Arduino, just heard of some awesome stuff and have a project in mind that could use it. I don't know if computers can even send messages to Arduino setups.
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Grand Blanc, MI, USA
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Sure, anything can be done given enough time and money smiley-wink

Arduinos and other microcontrollers can indeed communicate with computers. Addressing individual stations is not an issue.

Connecting 30 stations to a Mac would probably require some intermediary device, as 30 cables cannot conveniently be connected to a single Mac. Then there are also wireless solutions. Whatever software on the Mac that is sending the signals would need to be designed together with the electronics to interface to the stations.

Still feel like I'm about three-quarters in the dark here. A nice, reasonably complete problem statement would be great, one that doesn't make any assumptions about the solution. PM or email me if you'd prefer.
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Just throwing some ideas into the wind here.
You build individual devices (maybe with the ATTiny85) that have a 6 or 8 port DIP switch connected to a 74HC165 and bus pullup resistor to select it's address or the address could be programmed into the device. It also has a RS485 or RS422 chip to receive commands from the PC. A relay to control the mains device and a 3 pin bi-colour LED (Red/Green/Yellow) The PC command data structure contains an address and then the command, all devices hear this command but only the one who's address matches act on it. You could also have a global address that all devices work on so all equipment can be turned on/off with one command.
The connecting cable would be 2/4 core or more to carry (power?) comms and each device has an in & out connector to allow daisy chaining.
The MCU would get the on command (maybe with a duration) from the PC and then do all the countdown timing before turning the relay off but sending another on command will restart the countdown or an off command will turn it off instantly.
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Riva,
Google X10, off the shelf components, easy intigration with arduino and computers.
TomJ
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Einstein once said you don't really understand anything until you can explain it to your Grandmother

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