Computer Controlled Fireworks Display

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crapflinger
 
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Computer Controlled Fireworks Display

Post by crapflinger »

i'm planning on building a PC controlled fireworks display using two of These serial connected relay controllers (you can multiplex them with a kit to make them work as one device)...i'd prefer to NOT get a 100+ foot serial cable....so i searched for wireless serial connections....all roads point to the xbee.... and quite a few of them point to the ADAfruit xbee adapter kit as something that makes it all easier to use... now my biggest hurdle at the moment is that i'm an electronics ludite....i'm not very good at figuring out the wiring and such (i can learn)

basically i'm thinking that i can hook up an xbee with the adapter board to my pc with a FTDI cable and this will let me send serial commands over the air through the xbee to another xbee....but on the other end i just want to make sure i can do what i'm wanting to do...i would imagine that i'd connect the common ground to the common ground pin on the adapter to the ground pin on the serial port of the relay board (pin 5) then the rx of the adapter to the tx of the relay (pin 3) and the tx of the adapter to the rx of the relay (pin 2)....as a base set up i'd imagine this would work to send the data (basic text codes) to the relay....but the relay board has inputs and it can send data back as far as the status of the relays and all kinds of funky stuff....so would i/should i need to connect up the rest of the pins?

also....i'm wondering about powering the two xbees...both the local and the remote....is the local one powered through the connection to the FTDI cable? the remote one will be in a box that will have some form of power...probably a 12v battery to power the two relay boards and a 24v battery to make the *boom boom* (if you pass 24v across the right resistors the burst into flames and can light gunpowder)...if anyone could tell me what i'd need to either step down the 12v power to the 3v/5v needed to power the xbee or any suggestions on powering the thing for at least an hour or two with it's own battery i'd be really appreciative

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Re: Computer Controlled Fireworks Display

Post by adafruit »

eveything is OK except that the module uses 12V serial (which computers like) not 5V (which xbees need). you'll have to stick a MAX232 chip between the xbee adapter board and your controller. there is bazillions of examples online for how to wire up a max232. its easy and they can be powered off of 12V.

likewise, to power the remote XBee use a 7805 5V regulator (super common) on the 12V power supply and make sure that its outputting 5V. then you can plug that into the xbee adapter board's 5v pin

otherwise, it should work just fine!

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richms
 
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Re: Computer Controlled Fireworks Display

Post by richms »

Or since that box has a 232 or similar inside it and a regulator etc then pop out the 232 from its socket and get power and serial from there straight to the xbee, then you can stuff it inside the large plastic box so its protected from being dropped etc and save on some components.

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crapflinger
 
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Re: Computer Controlled Fireworks Display

Post by crapflinger »

see this is the part where hand holding is needed hehe

i know the basics of what you guys are saying but clarification is good so tell me if i'm right here in what you're saying

on the PC side...all the voltages should be right if i use the usb/serial cable (FTDI) that you can get with the kit from adafruit...i'd assume that it's designed to get the voltage right from the USB (5v)...

but on the other end...there's no voltage being supplied by the serial connection...the relay board is powered by a separate power supply (at 12v) and i can power the xbee at 5v from some source...your suggestions would be to either tie in a separate regulator to drop from 12v to 5v into the 12v source for the relay board...or in theory figure out a way to use the one that's assumed to be in the relay board already?




there's a chance that i may use a PC PSU in the box to power the relay boards (easy source of 12v)...but that would negate the purpose of having anything wireless there..

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richms
 
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Re: Computer Controlled Fireworks Display

Post by richms »

Inside the box there is a socketed max232 chip which is converting the ttl which goes to the atmel into the rs232 that goes to the socket on the back.

Its pretty inefficient to convert it to rs232 only to convert it back just the other side of it, so what I would do is remove the socketed max232 chip, and then use its socket as a place to get to the 5v, ground, transmit and recieve connections and hook that up to the xbee adapter. If you are want to make it reversible just get a 16 pin IC socket and solder to it, and then plug it into the existing socket on the board in there. Thatway you can swap the max232 back in when done with this and make it as origional. If you just stick wires into the IC socket you are likely to bust it.

Pin 16 will give you 5v, pin 15 is the ground, and you will find the signal that goes to the controller on pin 12, and the signal out of the controller back to the PC on pin 11. The other side of the max232 connects straight to the 9 pin socket on the back, and will become inactive without the max232 chip in place.

I always get confused with tx and rx naming of things, so if you hook it up with tx to 11 and rx to 12 and it doesn't work, then swap them around.

If you really want to make up a level shifter to keep the xbee external then there are several schamatics online on how it is done with the max232 chip - its the industry standard on how it is done so easy to find. There is another chip that doesnt need the capacitors to do its job, I haven't used one myself and it costs more.

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