Reef Discussion

MagicJ

Moderator
Jul 11, 2011
9,650
3,761
Hobart, Tasmania
Has it really been that long since I updated this thread :eek

A few things have happened...

I had a few computer problems and, in early June, I lost my latest sketch - long story, don't ask :banghead Anyway, I am pretty sure I have got back to where I was and the sketch is close to being finished.

As you may remember, this controller is being designed to control 10 separate channels. Whilst the Arduino Mega has 15 PWM pins, only 6 are readily accessible, due to the LCD shield, which leaves us a few short. I have also been mindful of the fact that the Arduino/Screen is likely to be remote from the LED drivers and we don't want 12+ wires going between the components - I have been planning on using some 8 core Cat5 cable for this purpose.

So, I have been planning on using a TLC5940 IC which operates over the Serial bus and provides 16 PWM channels - I already had some of these and have been designing the sketch around this solution.This requires 5 wires + 5v + Ground and so I would have one extra wire to use for a temperature sensor.

After quite a few hours trying to work out the best way do the layout on some vero board I came up with this

TLC5940.JPG


And found the time to solder up a board on the weekend.

I had also purchased a mini board from Adafruit quite some time ago which incorporates a PCA9685 IC - this also provides 16 PWM channels but operates over the i2c bus which only requires 2 wires + 5v + Ground. This was always going to be a better solution but I was mindful of the extra expense - this chip only comes in a Surface Mount format (i.e. tiny) so the mini board was the only way to use it . After much deliberation (or maybe it was procrastination) I have made the decision to ditch the TLC5940 and go with the PCA9685.

This was done for 2 reasons - making the vero board with the TLC5940 and associated components was time consuming and using this IC would limit the ability of anyone to put together this controller themselves. Yes, I could have made up the board for anyone wanting one but I think I would quickly tire of that :rolleyes. By using the mini board anyone can buy it if they want too.

The board is available from http://www.adafruit.com/products/815 and costs around US$15 + postage. I have ordered a number of these to get a few controllers up and running. Unfortunately, the fall in the AUD over recent weeks has made this a bit more expensive than it might otherwise have been.

This is a picture of my completed TLC5940 board together with the Adafruit mini board

Circuit.jpg


Hopefully, by the time these arrive I will have everything else finished.

Hopefully ......
 

macca_75

Member
Apr 22, 2012
2,125
844
Geez I wish I knew some of the hold up was over whatever techno babble is above - I would have ordered the $15 part and shipped it that day.

Keep up the great work - really looking forward to seeing it work.
 

Buddy

Member
Mar 13, 2012
3,142
1,526
Geez I wish I knew some of the hold up was over whatever techno babble is above - I would have ordered the $15 part and shipped it that day.

Keep up the great work - really looking forward to seeing it work.
Yep also cant wait :D
 

MagicJ

Moderator
Jul 11, 2011
9,650
3,761
Hobart, Tasmania
I changed over to the new PWM board shown above - it is now conflicting with my Real Time Clock library :banghead

So, I am currently rewriting the sketch to work with another RTC library o_0

And, I have a sore throat again - thought I had got ride of this cold :(
 

deediro

Member
Jan 19, 2013
85
40
Roxburgh Park
Amazing work - can't wait to see this finished and seriously aplaud how good this is looking!

I changed over to the new PWM board shown above - it is now conflicting with my Real Time Clock library :banghead

So, I am currently rewriting the sketch to work with another RTC library o_0

And, I have a sore throat again - thought I had got ride of this cold :(
It shouldn't be too hard to add a few more thermometers to the i2c bus for monitoring should it? Is there a limit on the number of things we can have hanging off it?

*Google reports between 112 and 127 devices.

Also, looks like the PCA9685 has an inbuilt clock but I'm guessing we still need an RTC for power outs?
 
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MagicJ

Moderator
Jul 11, 2011
9,650
3,761
Hobart, Tasmania
@deediro

I can see the light at the end of the tunnel :rolleyes

The easiest temperature sensor to use is the DS18B20 which doesn't actually use the i2c bus - all it requires is a digital IO pin and power. The plan is to include some temperature controlled fan connections in the final build.

And, yes, the PCA9685 dos have an inbuilt clock but only for looking after the PWM outputs of the chip - it can't be used for any other purpose so we will still need the RTC to control the overall timing of the controller.

The clock in the PCA means that once the chip is told what to do it no longer needs the Arduino - that is, until we need to change the PWM settings.

This feature may be somewhat useful - at the moment when I want to reprogram my existing controller I need to unhook everything which means that I loose my lights. With this PCA9685 chip, I can wait until after my lights are full on and unplug the Arduino - the lights will stay on :D
 

newbiereef

Member
Nov 8, 2011
874
154
gracemere
@deediro

I can see the light at the end of the tunnel :rolleyes

The easiest temperature sensor to use is the DS18B20 which doesn't actually use the i2c bus - all it requires is a digital IO pin and power. The plan is to include some temperature controlled fan connections in the final build.

And, yes, the PCA9685 dos have an inbuilt clock but only for looking after the PWM outputs of the chip - it can't be used for any other purpose so we will still need the RTC to control the overall timing of the controller.

The clock in the PCA means that once the chip is told what to do it no longer needs the Arduino - that is, until we need to change the PWM settings.

This feature may be somewhat useful - at the moment when I want to reprogram my existing controller I need to unhook everything which means that I loose my lights. With this PCA9685 chip, I can wait until after my lights are full on and unplug the Arduino - the lights will stay on :D

does this mean REEF MAGIC MARK 1 is nearly ready???? :D
 

Junnz

Member
Jul 22, 2013
8
5
@MagicJ this is controller is amazing, the work you have done on this will defiantly surpass allot of controllers on the market. keep up the good work bud. astounding
 

newbiereef

Member
Nov 8, 2011
874
154
gracemere
Flattery will get you absolutely nowhere :p

But, I am pleased to say that two packages did arrive in the mail today - the PWM boards from the US and some Dupont connector terminals from China.
WOO HOO CHRISTMAS HAS COME EARLY !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 

VaultBoy

Member
Jul 10, 2011
2,279
673
Gawler, S.A.
@MagicJ I am sooo glad that you are carrying this through! When you got started and and it looked good I stopped even thinking about building mine and now I am depending on you to finish so I can get more from my light as the arduino connected at the moment is only setting the colour mix...

I really cant wait for this!
 

MagicJ

Moderator
Jul 11, 2011
9,650
3,761
Hobart, Tasmania
What's happening here - @newbiereef has tried flattery and now @VaultBoy is trying the guilt trip :p

Just out of interest, for those that might be interested, who would like the hardware to be provided i.e. everything needed to plug it in and connect up to your LDD boards. I have some Arduino Mega's, LCD screens etc and may be prepared to find some more if there is sufficient interest. A box or two to put everything in is not available at this stage although I am playing around with a few ideas, with no guarantees.

The List

@Synodontis
@newbiereef
@Buddy
@Sam Parker
@longlenium
 
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