Must-haves for EASY DIY controller?

[terahz]

MaLi,

Initially I had 'PH = analogRead(pin)/50', but now I changed it to 'PH = analogRead(pin)/46'. It doesn't really matter though. With both calibrations and factors, when I dip in the 4.0 PH solution, the value is spot on.

So the final code looks like this now:

void getPH( void ){
  double sum = 0.0;
  uint8_t samples = 15;
  for (uint8_t i=0; i<=samples;i++){
    sum+=analogRead(PH_READ_PIN);
    delay(20);
  }
  PH = sum/samples/46;
}

 

[MaLi]

MaLi,

Initially I had 'PH = analogRead(pin)/50', but now I changed it to 'PH = analogRead(pin)/46'. It doesn't really matter though. With both calibrations and factors, when I dip in the 4.0 PH solution, the value is spot on.

So the final code looks like this now:

void getPH( void ){
  double sum = 0.0;
  uint8_t samples = 15;
  for (uint8_t i=0; i<=samples;i++){
    sum+=analogRead(PH_READ_PIN);
    delay(20);
  }
  PH = sum/samples/46;
}

TeraHz,
Thank you. What is the logic behind "/50" or "/46". Isn't this a bit probe dependent ? The reason I ask is because I use currently a probe that with the above code brought me to the end of turns for RV2 (original pH meter design) even before reaching pH 7 for the calibration fluid of 7. I will try a different probe this evening.

cheers,
Marian

 

[terahz]

The calculations are based on this statement from the original pH circuit from Richard:
"... a standard ph probe will give 0 -14 ph in 0 - 3.148v ...".

From that I derived about ~46 factor. I can post the math if you're interested.

It is strange that you're not getting within range. I have quite a lot of play room with either 50 or 46. They are within a few turns of the RV anyway. It is very likely that your probe is different. In that case, you'll need a datasheet. I'm using a BRS probe.

 

[ZenMastr1968]

OK, got the parts I was missing or didn't have enough of off the latest BOM today and I've got all my header and jumper blocks cut. Going to start soldering when I get home tonight.



Oh and DWZM, I'm heading to the PO in the morning....

 

[MaLi]

OK, so looks like the PH calibration is going to be interesting. I got the voltages based on the text that came with the PH circuit, but after I ran the numbers myself, I get different voltages... That being said, just skip the multimeter calibration above and do it with the LCD, that will be good enough. Right now we have a factor of '50' that converts the AVR reading to PH, but we might change it to '46' as that seems a bit closer to my calculations. Either way, the outcome should be the same. Changing the factor it will just shift the resolution which is probably higher than that of the probe anyway so it doesn't matter. Enjoy.

I can confirm that the voltage does not correlate with the display. Yet to understand why, but like TeraHz, as long time as I recover the calibration numbers I am OK. If I get some more time I will dig into, but is not top of my priorities. BTW, the code works well for the ORP side as well (no division with 46 of course),

cheers,
Marian

 

[shirley386]

I've been following this thread for a few weeks and I want to try to build one. When will it be "released" or ready for the general public to attempt to build? When/where can I get 2 or 3 boards?

 

[der_wille_zur_macht]

shirley, I don't think we can predict a date for a final official release, but I would be very confident in saying that if you built according to the current hardware design, you will have a functional controller that will do all the things we've discussed so far. The only thing really "missing" at this point is an official release of the firmware, but there are definitely enough examples of what various people are experimenting with that you should be able to get started.

As far as getting 2 or 3 boards, your best bet is batchpcb.com or dorkbotpdx.com - these are really the only places that will sell such a small quantity without totally ripping you off. We have published gerbers for the current design but they are intended for seeedstudio/iteadstudio, so if you use batchpcb or dorkbot you'll have to check against their specs, or just download the Eagle files and generate your own gerbers.

 

[ZenMastr1968]

New board is on-line...

had a little trouble with the d2pak IC but with more practice that will get easier.

will work on getting the sketches on and start doing some testing...

 

[terahz]

ZenMastr1968,

That doesn't look like the right part for U12 (size wise).
The package should align perfectly with the silkscreen, should not cover the "swiss cheese" area around it, and the pins should be right on top of the pads:

Did that part come from the BOM?

 

[nauticac4]

Dustin,

Have you played with the relay board and gotten it too work?

Planning on doing an order next week and was going to have both boards made.

 

[DustinB]

ZenMastr: That part definitely looks too big. Do you have the part number for it?

Nauticac4: I edited my board to add the resistors for the base of each transistor. I still need to switch a couple of the NPN transistors out with PNP transistors to simulate a normally closed condition. I haven't had a chance to order any boards yet. I've been extremely busy the last few weeks with xmas, end of year workload, closing on some property a few hundred miles away, etc... It's been crazy. I am happy with the board that is on the SVN site. I am confident it will do the job, I just need to make a BOM for it. PM me if you want to split some boards, either one of us can do the order.

 

[ZenMastr1968]

ZenMastr1968,

That doesn't look like the right part for U12 (size wise).
The package should align perfectly with the silkscreen, should not cover the "swiss cheese" area around it, and the pins should be right on top of the pads:

Did that part come from the BOM?

Yes, I didn't have the right one before and these came yesterday - straight off the BOM. Mouser Part# 511-L7805ABD2T-TR Chip is engraved L7805AB2T....

 

[mammut89]

hey guys , looks like this is becomming more and more a success. I was wondering if anyone has a board I could buy from this batch. ( just the board not assembled )

 

[terahz]

Yes, I didn't have the right one before and these came yesterday - straight off the BOM. Mouser Part# 511-L7805ABD2T-TR Chip is engraved L7805AB2T....

Yep, these are all wrong. They are supposed to be DPAK, not D2PAK. I've updated the BOM.

 

[shirley386]

hey guys , looks like this is becomming more and more a success. I was wondering if anyone has a board I could buy from this batch. ( just the board not assembled )

I want some as well and I don't trust myself with the Eagle/Gerber thing. I would appreciate anyone ordering boards to PM me. I want 3 boards and can PayPal immediately.

 

[terahz]

mammut89 and shirley386, Thanks for joining the thread. Someone a few pages back had ordered boards, you should contact them if they have extra. However at the price iTead Studio makes them (~$30 bucks) you might as well do it between the two of you. It comes to $3 per board, and even if you keep half, that's only $15 which is probably cheaper than a single board from BatchPCB... That being said, I just want to repost something in the interest of not getting moderated/closed down.

All,

Seems like the project is starting to gain some momentum - there are lots of "new faces" in the thread, and lots of talk about people building controllers now, so I thought I'd take a moment to post two friendly reminders that may have been buried in the earlier pages of the thread:

1) Reef Central does not officially allow the organization of "group buys" even if it's purely out of a desire to help other hobbyists - so, please take those activities offline from these forums. We realize this is awkward for things like PCBs since most board houses want to sell you at least 10. You can definitely work with fellow hobbyists offline (i.e. email) to organize that, or just buy from a place that'll do small quantities (batchpcb or dorkbotpdx come to mind).

2) We're releasing this project under a Creative Commons license. Specifically, the BY-NC-SA 3.0 License. This is a common license for "open source" projects like this. The intent is that we WANT people to be free to use, copy, or modify this project for their own personal purposes - we want people to use this design. But, we want to make sure it's done in a way that we see as "fair" to everyone involved. We care so much about this license that we've imprinted it on the silk layer on the board and mentioned it in this thread and on the google code site where we're hosting the project files for now. We hope that people choose respect this license because we basically have no realistic means of enforcement other than trusting fellow hobbyists.

The basic jist of this license is that anyone is free to use, redistribute, or modify the elements of this project (hardware and software). However, there are three restrictions (the BY-NC-SA part indicates the restrictions). These are:

BY: Attribution. You must attribute the original project. That means, if you modify or distribute the project (i.e. you post about your modified version on another forum, or post build shots of a "stock" Hydra on your blog), you MUST attribute the original project. For now, our preferred method of attribution is linking to this thread.

NC: Non-commercial. You may not use any elements of this project for commercial gain or personal profit. This means that you CANNOT make money as a result of this project. For instance, if you buy a bunch of sets of components for the BOM, for a cost of $10, and it would cost you $2 for postage to ship them to fellow hobbyists, you CANNOT charge $15 and pocket the extra three bucks "for your efforts." Or, for another example, you cannot put original-to-this project software components on your own design of controller and sell it for profit. (You CAN use components of the software in your own design, as long as your design conforms to this license).

SA: Share-alike. If you modify the project and redistribute your modified version, you MUST do so under the same license (CC 3.0 BY-NC-SA) or any more-current creative commons license with the same three restrictions. In other words, you cannot change a few things on the board, come up with your own name, and then distribute it under a closed license that doesn't meet the terms of this license.

More details can be found here if people are interested in the legal fine print:

http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode

Hope that this post isn't stifling to anyone's interest in this effort!

 

[fillibar]

About purchasing boards, with this being an Arduino-platform the code base could run on a standard Arduino right? (Sorry if this has been covered before). With the iTead Studio selling a MEGA for ~$45 complete, and the current PCB board production cost I saw on batchpcb.com was ~$40, the savings could be significant. One other thing, you mentioned dorkbotpdx.com but it is actually dorkbotpdx.org.

 

[nauticac4]

This board that has been designed here incorporated many features that would cost considerably more money to tack onto a standard arduino board.

Those arent the cheapest or fastest places to get a PCB made either. Plus that $40 is for 10 boards. $4 bucks plus the $80 or so in the BOM gets you quite a bit more than a standard Mega is capable of for $80 bucks

 

[terahz]

About purchasing boards, with this being an Arduino-platform the code base could run on a standard Arduino right? (Sorry if this has been covered before). With the iTead Studio selling a MEGA for ~$45 complete, and the current PCB board production cost I saw on batchpcb.com was ~$40, the savings could be significant. One other thing, you mentioned dorkbotpdx.com but it is actually dorkbotpdx.org.

Yes, the code is on the arduino platform. Yes, it will run on standard Arduino, but most the hardware required for all features to work is not on standard arduino (PH, Ethernet, RTC, LCD expander etc). In addition, the firmware work on 2 AVRs. So you would need 2 MEGAs + other expansion boards to mimic the hardware that's on the Hydra board. That will make it much more expensive

You can't really save any money by not using the Hydra board if you want the Hydra functionality.

batchpcb is way too expensive. For $28 you will get 10 boards from itead studio.

 

[shirley386]

For $28 you will get 10 boards from itead studio.

OK, what does it take to order the boards. I'm ready to order them. I only need about 3 but I'll buy 10 if that is what it takes. I can share the rest with others.

If this is getting in an area in conflict with RC's rules about bulk buying and reselling please PM me. I don't want this thread closed due to that.

Also, anyone else that wants a board can PM me as well.