interest? Arduino shield

[AndyL]

G'day All,

Decided it's about time... I've built the arduino circuits for port expanders, RTC, EEPROM and pH Op Amp circuit 3x now... And here I go needing it again...

How much interest is there in a shield - designed specifically to address the 'normal' needs of reef/aquarium/hydroponics users?

Got the schematic done: http://picasaweb.google.com/lh/photo/hIVc5cdJPBKA53UgSa4CVw?feat=directlink

Once I get it fit onto a nice shield setup (so you can plug it in to the arduino - then plug in your normal accessories) - expectation is to have a run of PCB's done; as I know there's more than a few people who are shy of the heavy duty circuit design/building.

Basically - shield is designed to handle the basics for any grow system; Give you a nice connector for your LCD & keypad to plug in; circuit & bnc for your pH probe (reads from 4-10), real time clock, data storage. And throw in 16 more digital i/o's in case you're controlling a huge system. All it's using at the moment is 3 of the analog pins from the arduino (SCL/SDA & analog 1); rest of the pins are available. Shield will allow further shields to stack on as intended...

This first version is based on DIP components so any of us can build one - as such there's a few limitations (ie need for a 12v power source for the pH circuit).

Working on the second version already - using pretty much all SMT parts - intended as a production version (ie have a production run done completely assembled and ready to plug in). Eliminates the 12v power source, and is much more compact & cheaper to produce & assemble.

But I figure I should ask - anything I'm leaving out anything major? I'm covering the basics of my typical circuits; but we all have different needs - trying to ensure I cover the majority; so it's as useful as possible...

Thoughts? Comments? Suggestions?

Andy

 

[rsuplido]

You might want to consolidate efforts with this project: http://www.nano-reef.com/forums/index.php?showtopic=196161

 

[AndyL]

Perhaps - but I think we share some different design goals Thus keeping them separate might be better... I'm looking at a wider use; and different overall goals - I'm not aiming to provide a complete package; just a component to allow anyone to plug it in and put together a system based on their needs... Not to provide a complete system...

 

[stugray]

AndyL,

I have a suggestion - try to make your shield compatible with the other shields that people are most likely to want to add like the ENET.

And if it even possible, can you make your shield stackable so that you could put on multiple units? Maybe jumper configurable "addresses" so you could stack a number of them and address them all separately?

Stu

 

[AndyL]

Yup; intention has always been to follow the true shield format - allowing one to stack on the nokia lcd shield etc - this is partly why I used two port expanders - keeping pretty much all the base ports still available.

I have the debate with configurable addresses; I started by using DIP switches for hardware assignment... Then decided it's better to hard code it - limits the 'errors' of wrong addresses; making software less troublesome... The DS1307 chip defaults to 0x68 in the DIP package; so it seemed to make more sense to hard code all of them...

My general goal is - I don't know how people are going to use it... I know how I need it; but figured it's best to make it as open as possible allowing persons to tailor to their needs... Thus I've used the wide range pH circuit (4-10pH) because the freshwater and hydroponics types may will want the lower end... And really - does a difference between 7.17 and 7.20 make a difference - usually we're aiming for the tenths scale, the hundredth's are less relevant whether it be reef, hydro, freshwater, or ?!? who knows who else might find it useful...

 

[AndyL]

Brought up by some others - pondering adding a control circuit for pc fans (12vdc) into the circuit... Thought about it - and it would seem to be one of the basic items many of us would want; would be a pwm circuit - take away two of the pwm channels off the base arduino board... But then you'd have speed control over the pc fans - fair trade off in my eyes, controllable speed vs my original thought of straight on/off control...

Thoughts?

 

[stugray]

With fan speed control, you also get LED dim capability.

How many hardware PWM pins does the Mega have?

Just a PWM pin, single MOSFET, & screw header for each & you're done ( add a Optocoupler for extra protection if you want to be fancy ;-).

Stu

 

[AndyL]

There is that... But I have some different thoughts about LED's that'll be coming up as a totally different shield design (Yes growshield design is such that you can still stack other shields above/below)

This is version one - of the growshield; it's designed to be home built if desired - all DIP components so easily soldered... Will be releasing the design once I wrap it up a bit more - including board layout. I'll have some PCB's run once I get the testing done; perhaps even build a few for those who are challenged when it comes to soldering...

Version 2 - will be basically the same design but SMT parts designed to be fully assembled in china those boards hopefully will be available next spring

Started work on Growshield-LED last week - it's another arduino shield; designed to handle 8 (i hope) LED arrays by themselves... Eliminates all your buckpucks etc - tie your arrays and a adequate DC powersource directly into the shield, and the shield handles the rest; onboard drivers & digital pots set, monitor and adjust current as needed... And of course PWM dimming of each string individually. But it's going to be a long way out, there's a few design challenges involved - but hoping to have a prototype circuit running in the new year...

 

[stugray]

AndyL,

Does your growshield have the dimming circuit on-board, or does it depend on a PWM pin from the mega?
It would be relatively easy to put the PWM circuits on-board then control them via 1-wire EEPOTs.

"there's a few design challenges involved "

Tell me what your challenges are & I can help.
I have designs that incorporate serious fault tolerance ( using opto-couplers & extra TTL I/O from the micro ), with high current & voltage MOSFET drivers.

I am aware of the things that can Kill LEDs and how to avoid that even with software in the loop.

Let me know & perhaps I'll share some designs with you.

I have even done some work with the dallas 1-wire stuff as well as remote power control.

Stu

 

[AndyL]

Haven't dealt with the mega yet - i'm sticking with the Freeduino SB; little easier to find and less expensive than the mega...

I'm sticking with keeping the nice basic use the PWM pins off the arduino; I'm not quite the EE genius you are I try to keep things rather simple... Thus this shield design - it seems silly to have people recreating and asking the same circuit questions over and over; my thought is a simple shield - cover the basics and make room for expansion for more presonalized needs...

Design challenge - nothing major, just working through all the fun choices on IC's etc - cooling will be a bit of a challenge but nothing extraordinary. Trying to pull it all together so it's as simple and redundant as possible, and cover the basis of peoples needs through the basics (won't handle the extremes of course but; handling the average up to 20g seems reasonable).

 

[stugray]

"i'm sticking with the Freeduino SB"

Sorry, another project I am looking into is the Mega.

So you could control: 6 motors,LEDs, or fans in any combination.
Leaving 8 I/O pins plus 6 AtoD inputs.

Are the remaining 8 pins enough to communicate with your shields?

Do you have 1-wire capability?

Stu

 

[AndyL]

Freeduino SB is a slightly modified version of the arduino duemanilove; (same basic setup as the mega - just not as many pins).

Right now; initial shield design encorporates a pair of 16 port I2C expanders, an i2c eeprom and RTC. Encorporates the base circuit for a HD44780 LCD (just plug it in and go) and 4x4 keypad. Leaving the 14 base digital I/O's untouched (well - will have to use two of the pwm i/os with the addition of fan control) adds 16 digital I/O's; of the 6 base analog i/o's - 2 are use (scl/sda - for the i2c bus - still available for further tie ins though) and analog 0 for the pH probe... 1-wire is natively handled on all the arduino's (worth mentioning - you can have multiple 1-wire devices per i/o for those who think it might not be enough already).

Generally unless you're talking a huge system - should still cover all the bases for most tank systems...

 

[shackscs]

Just checking to see how you are progressing with this project?

Anything further? Have you started getting interest for boards/units yet?

 

[AndyL]

Still plugging away; working my way through a complete revision at the moment - had some minor issues with the first design (made a mistake with power feed).

Interest has been moderate - once I post up a completed unit - with a nice easy to use GUI front end - have a feeling that's going to change

 

[MaLi]

Andy, I was one of the few who built and Arduino based controller way ago. I am interested on your work and we appreciate you making this public domain. Keep us posted. Thank you.

cheers,
Marian