Setting up LEDs on Timer + Dimmer circuit, help needed

[pescadero]

for you bitnerds: i ran across a site last night about using a linux bash script to control swimming pool chemistry. looks like it would be fertile ground for DIY aquarium automation.

[MeuserReef]

I have been considering the idea of making something out of a 555 IC timer just for the sake of learning a bit more about electronics.

Anytime I get the chance to learn something new and play in my fish tank, Im game!


{Quietly subscribes to thread}

[BeanAnimal]

My feeding timer is a monostable 555 circuit

[stugray]

Use a chip like the:

DS1804-010-ND

for ~$2 from digikey.

With two digital lines from any computer you like, you can adjust the resistance up & down.

Stu

[RyanBrucks]

Sounds cool!

out of curiosity:

the ISK aquastar claims dimming capability

"The extensive day/night simulation makes child's play of your aquarium's lighting and optimises it too. You can use it to set a wide variety of lighting on- and off times. If the lighting you use can be dimmed, you can simulate sunrise and sunset. It's even possible to recreate the sunrise and sunset of a particular region of the world (by entering the latitude and longitude.This function even makes the period of the
reduction in nocturnal values possible (pH-value, temperature, current etc.). "


Can anybody comment on exactly what the sunrise/set functionality is? Is it something limited that only works on T5s (like their sunrise model)?

If this truly does do light sunrise sunset in a programmable way (in addition to all the other sweetness), then I might just have to consider it.

Of course, I'm probably dreaming, it's probably not the full-fledged-programmable-dimming that I've invented in my head.

Ryan

[RyanBrucks]

also, the aquacontroller claims 'moon cycle'

"Moon Cycle Simulation

The AquaController III Pro has another special type of timer which can be used to simulate the moon cycle in your tank. The lunar simulator is used for this feature and is capable of varying the intensity of light emitted from its LEDs. The intensity variations are controlled by the AquaController which is preprogrammed with correct intensity values for each day of the moon cycle. The AquaController automatically updates the intensity value depending upon the current setting of the AquaControlle's clock. With this artificial moon cycle, it is possible to induce corals and fish to spawn."

Sounds to me like this is exactly what I need.

Thoughts anybody?

Ryan

[BeanAnimal]

Ryan my homebrew controller does sunrise/sunset moonrise/moonset/percent of disk illuminated for any location on the planet. The first revision worked from a PC but the new version is based on an ATMEGA128 and a 5" touchscreen.

[pescadero]

that sounds like it worth discussing. did yoiu document the build?

[ronjeremy311]

I would be very interested in some build documentation. I am plenty capable of building a project like this if I have good documentation, I'm just not good enough to build it from scratch.

I plan on getting an AC3, so the Lunar Sim. would be an option except for the fact that my light has LED's built in. I'd rather not go chopping up a rather expensive light fixture if I can come up with a way to control the built-in LED's.

[BeanAnimal]

I am not even good at documenting code!

The PC software was pretty straight forward. VB.NET controlling relays. The setup was never run in production. It was a perpetual test bench kind of thing. The rest of the "controller" software was never complete (I had a huge list of features left to implent like alarms, sms messaging, voice messaging, status by phone, web based control, etc. I had most of the pieces working, but not alll tied together.

Anway, I embarked on the AVR Atmega 128 light controller a few weeks ago. The code is pretty much done and stable. I have the 5" touchscreen coming wednesday and need to debug the code for it. I also need to come up with a suitable enclosure. I may try to document the project once I get it debugged and running.

[RyanBrucks]

I think what would help us, more than the code, would be a list of what electronic parts you used (like circuits, chips, etc), and a rough example of how its laid out. The code part looks like pretty straightforward if/then stuff, but I am still HEAVILY confused about which electronic parts I need, and how to wire them, and how to connect that to my computer for programming (altough that looks easy to learn).

I can't wait until I have more time to dedicate to this part of my project, but for now I have a bunch of other tank-related setup work to do (finish building my 50G water changing tank, 50G RO tank, finish building garage stand/closet).

At this early stage, my rough understanding of how this might work is:


Microprocessor interfaces with PC, allows you to write a few lines of basic code (if time < X, then set voltage/curren=?). I assume these lines of code contain the voltage/current information?

I2C RTC allows the system to track time/date for use in code, wired to microprocessor

Microprocessor controls a digital potentiometer chip, and tells it what voltage/current to output.

--
For a digital potentiometer, do you need to use a DAC?

If I'm understanding correctly, the 555 and the microprocessor implementations are completely separate (one is digital, one is analog).

For using the microprocessor to do smooth dimming, would I just need to create an expression that raises current exponentially(or linearly for lazyness++) over a given timeframe?

[BeanAnimal]

You pretty much got it

There are doznes of PIC and AVR demo boards available that can be programmed in basic. I2C, 1-wire, LCD, Serial, etc are all pretty mcuh standard built ins to the compilers.

I prefer BASCOM-AVR (just learning it this week) over the PICBASIC stuff.

You can literaly have a program up in running in minutes with either. The atmega88 and similar devices come in DIP packes so soldering will be easy. They lack enough power and program space to be full blown aquarium controllers, but will work fine for just about anything else.

Ther appears to be much more community support for the picbasic than there is for bascom. If you are more comfortable with C then either will do (there are many more programmers that know C than there are that know basic)

It is a very interesting hobby!

[RyanBrucks]

I built some really uh... basic stuff (screensavers, buy-n-trade games, calculator etc) using Basic (pun intended) way back when. So I pretty much have a beginners knowledge of basic, and no real C experience.

But I don't think C would really be all the more difficult for a project with such minimal coding.

So was I also right assuming I would need a DAC for a digital potentiometer, or do those actually output raw voltage?


maybe I should go with a picbasic demo board, because you say there's alot of support for it, and because I already have basic experience.


Thanks,
Ryan

[BeanAnimal]

There are seveal ways to "dim" the leds. You can use the PWM output of the micro to do it, or you can use a DAC to do it. I would search around google a bit and look at examples of both types of dimming.

[RyanBrucks]

this makes pretty good sense to me

http://www.iguanalabs.com/pwm.htm

"You can see that the output is 0 most of the time and the LED or motor will be on most of the time."

is it just me, or is their explanation of tHigh vs tLow backwards?

[stugray]

Check out rabbit microprocessors. They have demo boards for under $100 that have built in ENET and free open-source enet stack software.

They even have some with AtoD or PWM built in:

http://www.rabbitsemiconductor.com/p...00/index.shtml

Once you learn how to run the chip, the unit price is less than $20.

Also see my DIY thread: 'I'll do anything for money $$$!!'

A PWM LED dimmer is one project that should be on the list, and I am currently sitting 2 feet from the circuit that I am currently trying to make do just that ( parts ~$5 ).

It is one project that- once one of us figures it out, we can all benefit. Maybe there should be an open-source DIY movement. Everyone pitches in to make it work as long as the step by step instructions are made public. We could even start a Wiki page for each build.

Stu

[barjam]

Man I really need to get into pic/avr programming. I have a buddy that made some AVR boot loader code that allows it to reprogram itself over a simple serial PC connection.... so I have no excuse not to get started.

[MeuserReef]

Stu,

Thanks for the link.

This definetly makes for some good reading material.

Are you using this chip?

[RyanBrucks]

yah, great product link

the RCM4400W has 802.11b wifi capability. With this I could reprogram remotely with ease

Strangely, the 4000 model has 32MB of flash memory for data, whereas the wifi enabled board only has 512K. Would 512k be limiting if I decided to try and program a complete aquarium controller in the future? Would I be better off getting the ethernet version and using a separate wifi solution?

"4 channels synchronized PWM with 10-bit counter 4 channels
variable-phase or synchronized PWM with 16-bit counter"

looks like I'd have enough PWM to run a host of operations.

*edits, rephrase * Is any kind of filter necessary when connecting the microproc to the potentiometer when using PMW? I seem to be missing what links the PWM output to the pot.

Or is PWM actually a replacement for a potentiometer altogether? If so, is the microprocessor supplying the voltage/current entirely, or is there another piece I am missing?

[pescadero]

Stu, I like your idea for an open source project. I'm kinda surprised that nothing like that has been started already.

as I see it, the biggest problem (for me anyway) is going to be to find the right programmable hardware for the job and creating the interfaces, rather than writing the code. in the big scheme of things i don't think that the choice of programming language matters that much, as coding in one language vs. another just involves getting used to different syntax. the fundamental concepts are pretty much the same.

as far as hardware goes, there are multiple ways that one could go in doing this. one would be to use a PC interface, antoher would be to use an embedded type of system that can run without a PC. i'd prefer an embedded system that draws less power than leaving a PC running 24/7. the choice of an embedded, non-proprietary freeware solution essentially means that we'd need a CPU that runs on an embedded linux kernel.

[stugray]

pescadero,

"non-proprietary freeware solution essentially means that we'd need a CPU that runs on an embedded linux kernel"

http://www.newegg.com/Product/Produc...SYS-_-33124036

&

http://owfs.org/index.php?page=nslu2

The second link is specifically talking about 1-wire, but there are serial & USB ports on it, so you could do a lot more.

[barjam]

Or is PWM actually a replacement for a potentiometer altogether? If so, is the microprocessor supplying the voltage/current entirely, or is there another piece I am missing?

Replacement for. Sounds like LEDs run basically like an electric motor... you don't change voltage but rather flip the "switch" many, many times a second. The eyes would be unable to see the flicker (if present, not sure how fast a LED actually switches on/off visibly).

[RyanBrucks]

Looks like the PWM of those chips only outputs ~3volts?

I need ~30volts DC and 1 amp (1000mA).

Also, I believe that my icecap 430 ballast is dimmable so I'd like to control the brightness of the VHOs.

What device can I use to boost the current/power of the PWM to be enough for these devices?

[barjam]

You would run them through a Power IC... basically a relay. Essentially you would end up with a motor speed controller circuit.

Let one of the other guys respond though, I don't know much about electronics.

[Donw]

With PWM what frequency or cycle rate do you have to pulse a led to get 50% dim?

Don