pH probe with atlas carrier board

osterac · Feb 15, 2022

Hi,
I had posted this in the dev thread but I decided it was a better idea to make my own thread.
I have a Raspberry pi 2 I am trying to use for reef pi with a pond. I already have a thermometer working but I am trying to get pH working too. I bought The atlas pH circuit and the atlas carrier board (and a probe of course) but then realized the guide for this doesn't use the carrier board. I want to use the carrier board in my build because it would make everything much tidier but I haven't been able to get it working.
I get this error:

Code:

ph subsystem: Failed read probe:pH probeError:write /dev/i2c-1: remote I/O error

I have a pH ezo driver set up with an address of 99.
I have an analog input for that driver on port 0.
In the pH tab I have a probe set up pointing to that analog input.
on the carrier board I have it wired like this.
rx->sda1 i2c
tx->scl1 i2c
gnd->gnd
off->n/c
vcc->5v
Any tips?
thanks

osterac · Feb 16, 2022

Failed to mention -
this is the guide I was talking about:
Atlas pH probe guide
The guide lists the carrier board in the parts list but never uses it in the actual build

robsworld78 · Feb 16, 2022

My guess is you don't have I2C enabled on Pi.

osterac · Feb 17, 2022

robsworld78 said:
My guess is you don't have I2C enabled on Pi.

Thanks for the response.
Okay so I tried disabling and re-enabling i2c and then I did this:

Code:

pi@pond:~ $ i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

I thought that at least 70 and 40 were supposed to show up (or something like that)?

osterac · Feb 17, 2022

Got it working! Replaced the wiring going from the carrier board to the pi. Phew!
Thanks all

Ranjib · Feb 22, 2022

osterac said:
Failed to mention -
this is the guide I was talking about:
Atlas pH probe guide
The guide lists the carrier board in the parts list but never uses it in the actual build

the isolated carrier board is the same as the bnc connector. Its listed underthe parts https://learn.adafruit.com/reef-pi-guide-7-ph-monitoring/parts

its not a separate component

Ranjib · Feb 22, 2022

osterac said:
Got it working! Replaced the wiring going from the carrier board to the pi. Phew!
Thanks all

Nice

please do share build pic if you can. We love those

osterac · Feb 23, 2022

Ranjib said:
the isolated carrier board is the same as the bnc connector. Its listed underthe parts https://learn.adafruit.com/reef-pi-guide-7-ph-monitoring/parts

its not a separate component

The link listed is the parts list is the carrier board. The bnc connected they used in the guide is not listed.

Oh, and there is a pic in the original post, but I'll try to take some more of it actually installed when I have some time.

Ranjib · Feb 23, 2022

osterac said:
The link listed is the parts list is the carrier board. The bnc connected they used in the guide is not listed.

I’m not sure what you are saying, the part list calls this out (bcc connector and carrier board) as one item. And the link does takes me to the correct part

Electrically Isolated EZO™ Carrier Board (old style) | Atlas Scientific

The Electrically isolated EZO™ carrier board is an easy way to connect an Atlas Scientific EZO™ circuit to your CPU, eliminating the need for a bread board and an external isolator.

atlas-scientific.com

osterac · Feb 23, 2022

Ranjib said:
the isolated carrier board is the same as the bnc connector. Its listed underthe parts https://learn.adafruit.com/reef-pi-guide-7-ph-monitoring/parts

its not a separate component

This is what they used in the build

This is the part in the parts list

Ranjib · Feb 24, 2022

osterac said:
This is what they used in the build

This is the part in the parts list

Ah, I see what you mean now. The photos don’t match. I should update that, must have slipped my checks. You are right , the photo is a non isolated BNC connector. But the part listed and the build instruction should still be correct

osterac · Feb 27, 2022

Ranjib said:
Ah, I see what you mean now. The photos don’t match. I should update that, must have slipped my checks. You are right , the photo is a non isolated BNC connector. But the part listed and the build instruction should still be correct

It seems like the instructions are based around a non-isolated connector as well, though. With the carrier board, you don't need to solder up a proto board. You can wire the carrier board directly to the pi.

Ranjib · Feb 27, 2022

osterac said:
It seems like the instructions are based around a non-isolated connector as well, though. With the carrier board, you don't need to solder up a proto board. You can wire the carrier board directly to the pi.

That is because in the guide the 5v rail is shared between incoming power supply , pi and ezo circuIt, if I recall correctly. and pi is powered through header pin, not micro usb.

osterac · Mar 2, 2022

Ranjib said:
That is because in the guide the 5v rail is shared between incoming power supply , pi and ezo circuIt, if I recall correctly. and pi is powered through header pin, not micro usb.

Point is that the guide could not be followed by someone who had purchased the carrier board, because in the guide you have the ezo board plugged into a proto board and if you buy a carrier board it plugs into the carrier board.

Ranjib · Mar 4, 2022

osterac said:
Point is that the guide could not be followed by someone who had purchased the carrier board, because in the guide you have the ezo board plugged into a proto board and if you buy a carrier board it plugs into the carrier board.

Duly noted. I’ll update the guides whenever I find some time. They have not been updated for quite some time.

Osbie Feel · Jan 3, 2024

Ranjib said:
Duly noted. I’ll update the guides whenever I find some time. They have not been updated for quite some time.

Just going to chime in here with a friendly reminder that the guide still hasn't been updated

I'm a total raspberry/reef pi beginner and had already soldered most of the proto board before I realized the carrier board wouldn't work with it. Not sure I would have figured out what to do without this thread.

Ranjib · Jan 5, 2024

@Osbie Feel were you able to get your board working?

Osbie Feel · Jan 9, 2024

Ranjib said:
@Osbie Feel were you able to get your board working?

Actually no, I have run in to the same issue as the OP in this thread - I am getting an empty address table when running i2cdetect -y 1. Unfortunately replacing the wiring has not been successful. I have made sure that I2C is enabled on the pi and the ph ezo sensor. Any troubleshooting ideas....?

Sral · Jan 10, 2024

Osbie Feel said:
Actually no, I have run in to the same issue as the OP in this thread - I am getting an empty address table when running i2cdetect -y 1. Unfortunately replacing the wiring has not been successful. I have made sure that I2C is enabled on the pi and the ph ezo sensor. Any troubleshooting ideas....?

You switched Clock and Data cable, if I'm not mistaken. Try switching the blue cable to the RX pin and the yellow cable to the TX pin.

Here is the Raspberries Pinout of the I2C pins, pin 3 is data, e.g. your yellow cable.

Here is the datasheet of the old style Atlas carrier board that you seem to be using. The RX pin seems to be the clock. That's where your yellow cable (e.g. Raspi I2C data line) seems to be connected to.

Osbie Feel · Jan 10, 2024

Sral said:
You switched Clock and Data cable, if I'm not mistaken. Try switching the blue cable to the RX pin and the yellow cable to the TX pin.

Here is the Raspberries Pinout of the I2C pins, pin 3 is data, e.g. your yellow cable.

Here is the datasheet of the old style Atlas carrier board that you seem to be using. The RX pin seems to be the clock. That's where your yellow cable (e.g. Raspi I2C data line) seems to be connected to.

That did the trick! I've got the probe calibrated and collecting data now. Thank you so much for the help everyone, stoked to have my reef pi up and running!