Reef-Pi pH-ORP adapter

Roberto_b · Oct 16, 2018

Hello,
i have finished and posted the project open source for pH/ ORP adapter for Reef-Pi project.
The adapter can be used both for pH or ORP probe (standard with BNC), Ranjib is working to patch software for this adapter.
Is a optocoupled adapter, high resolution , in this way you can prevent any potential problem of leackage current in your tank. Up tp 4 adapter can be used in same time (a dip switch select the address), connected in parallel on I2C bus.

https://github.com/reef-pi/pH-Board

If you have any question or doubt i'm at disposal .

Roberto

TheEngineer · Oct 16, 2018

Welcome to R2R! It's really nice to see ReefPi coming along so far

Michael Lane · Oct 24, 2018

@Roberto_b I tried uploading the gerbers to Osh Park and encountered the following errors. It looks like Osh Park has a problem with the drill file and board outline. Is there another version of the gerbers that could work with Osh Park?

Ranjib · Oct 25, 2018

This is awesome @Roberto_b . Welcome to reef2reef. I'll get back to the board testing/driver development shortly after I am done with the guide writing,

Roberto_b · Oct 25, 2018

Michael Lane said:
@Roberto_b I tried uploading the gerbers to Osh Park and encountered the following errors. It looks like Osh Park has a problem with the drill file and board outline. Is there another version of the gerbers that could work with Osh Park?

hello, i don't know the osc park, but in any case .drl is not a gerber file, you can't open it, it's drilling file for dedicated machine, all other files in .zip are gerber.
Outline file is presente, tryt o check the pdf version or different gerber viewver.
let me know if ok, or if you like something more i can try to generate.

Michael Lane · Oct 26, 2018

I still can't get Osh Park to accept the gerbers, but jlcpcb had no problem with it. Now I just have to wait a few weeks for the boards to arrive. I'm looking forward to building this circuit!

Roberto_b · Oct 27, 2018

Great, let me know if you need help.

Michael Lane · Nov 6, 2018

Roberto_b said:
Great, let me know if you need help.

I finally received the boards and parts! Can you confirm that J1 should connect R2 for PH operation?

Michael Lane · Nov 6, 2018

Michael Lane said:
I finally received the boards and parts! Can you confirm that J1 should connect R2 for PH operation?

I realized that I just missed the pH and orp labels on the silkscreen, so I figured out J1. R7 and R8 are not listed in the BOM. I think those are the pull up resistors for i2c, do I need to populate those 2 components for use with rpi and reef-pi?

Ranjib · Nov 6, 2018

I think pull ups for i2c pin are good to have but not a necessity. For me though, the Ezo circuit didn’t work until I added 5v pull up (4.7k)

Des Westcott · Nov 6, 2018

I've just found this thread. Watching with great interest.

Roberto_b · Nov 7, 2018

Hello Michael,
yes, checking schematic & pcd layout pH configuration is done when jumper is closed with R1. See also the picture on github page.
do not mount R7&R8 , they are pull-up to +5V but I2c bus is 3V3, so is necessary use only the pull-up already present on Pi3. As Ranjib said if you use these pull-up the signal from Pi3 will be read alwasy logic 1, too high level signal and they are also out of silicon limit parameters.

Michael Lane · Nov 7, 2018

I have assembled the board, but seem to have some problem. The sample program consistently reads a value between 4000 and 4300. That behavior doesn't change when I move the probe to a different solution, or even disconnect the probe. I did confirm that the board is identified using i2cdetect. I haven't done a full trace on continuity to find something that may be a problem.
Maybe you see a clue?

Full size image at https://imgur.com/inelbEV

Michael Lane · Nov 7, 2018

Found it! There's a bridge between pins 12 and 13 on ADM3260. I was only able to find it by looking at the high res picture!
It's working great now that I fixed that. I'm reading around -12,000 in the tank now (totally uncalibrated), and around 5800 for RODI water. I can use board this to start working on driver and calibration support in reef-pi pretty soon.

Roberto_b · Nov 8, 2018

Great job, well done, better than my one !!
Kepp me informed as you proceeed with SW.
I'm working on daughter board now, i think you like also.

Ranjib · Nov 8, 2018

Michael Lane said:
Found it! There's a bridge between pins 12 and 13 on ADM3260. I was only able to find it by looking at the high res picture!
It's working great now that I fixed that. I'm reading around -12,000 in the tank now (totally uncalibrated), and around 5800 for RODI water. I can use board this to start working on driver and calibration support in reef-pi pretty soon.

Whoa

, this is super duper exciting :-0)

theatrus · Nov 11, 2018

Roberto_b said:
Hello,
i have finished and posted the project open source for pH/ ORP adapter for Reef-Pi project.
The adapter can be used both for pH or ORP probe (standard with BNC), Ranjib is working to patch software for this adapter.
Is a optocoupled adapter, high resolution , in this way you can prevent any potential problem of leackage current in your tank. Up tp 4 adapter can be used in same time (a dip switch select the address), connected in parallel on I2C bus.

https://github.com/reef-pi/pH-Board

If you have any question or doubt i'm at disposal .

Roberto

This is very nice

wykat · Nov 17, 2018

Roberto_b said:
Hello,
i have finished and posted the project open source for pH/ ORP adapter for Reef-Pi project.
The adapter can be used both for pH or ORP probe (standard with BNC), Ranjib is working to patch software for this adapter.
Is a optocoupled adapter, high resolution , in this way you can prevent any potential problem of leackage current in your tank. Up tp 4 adapter can be used in same time (a dip switch select the address), connected in parallel on I2C bus.

https://github.com/reef-pi/pH-Board

If you have any question or doubt i'm at disposal .

Roberto

I've taken some time to understand your design as it's of great interest to me. The PH measurement is on my 'next to do' list and I already have some reference designs, but since your design is specifically made for Reef-PI, this makes it even more interesting. While going through the documentation following questions came up:
- Why are 0603 components used and not 0804 or TH when possible?
- The ADS1119 allows 2 analog inputs, why is only 1 used and not optionally 2?
- Why is port 0x40 used as default? The same port is used for the PCA9685 module.
- Which PH probe are you using, would like to order one as reference
- Need the module to be placed close to the PH probe? Some probes are offered with 3 meter cable. My preference is to make a stacked PH sensor board to my Reef-PI_HAT.

Thanks for sharing your designs!