EZO issue on Ferduino Mega [SOLVED]

[Thomas di Maggio]

Hi guys,

I have an issue to solve. I bought Atlas Scientific EZO circuit for PH (1 arrived and 1 will be delivered soon), ORP (arrived) and conductivity (arrived). I connected them on slots 0, 2, 3 of the Ferduino Mega.
If I uncomment STAMPS_EZO, USE_STAMP_FOR_TANK_PH, USE_STAMP_FOR_CALCIUM_REACTOR, USE_STAMP_FOR_ORP, USE_STAMP_FOR_DENSITY without having any circuit connected there is no problem. Ferduino works.
With the same code, having the circuits connected as explained here the system doesn't work. On the TFT appears sometimes something not well defined for some second. Relays don't give signals of working.

With the circuit connected as said the only configuration that works (I mean that goes to the home screen, not even tested with probes) is with:
STAMPS_EZO --> active
USE_STAMP_FOR_TANK_PH --> not active (circuit connected)
USE_STAMP_FOR_CALCIUM_REACTOR --> active (circuit not connected)
USE_STAMP_FOR_ORP (circuit connected) --> active
SE_STAMP_FOR_DENSITY --> not active (circuit connected)

I also used the test code and everything seems ok. the connection result open for every channel but i think I have not well understood how does it works.

I really don't know what to do. Can you help? this with the stamps is the last huge step for me. Then I'll stop boring you!

[Fernando Garcia]

Hi!

Don't uncomment the line USE_STAMP_FOR_CALCIUM_REACTOR without a stamp connected to slot 1.

Which baud rate for serial 3 are you using in test code?

Ferduino Mega haven't isolation for stamps so you can get bad readings using pH and EC stamps together. It was an issue related by Atlas after Ferduino Mega be released.

You can check this information on datasheet page 9: https://www.atlas-scientific.com/_files ... asheet.pdf

When reading pH and Conductivity together, it is strongly recommended that the EZO pH circuit is electrically isolated from the EZO Conductivity circuit.

The solution now is buy this shield with individual isolation designed by me and assembled by Christopher.

Best regards.

[Thomas di Maggio]

If I comment USE_STAMP_FOR_CALCIUM_REACTOR anything changes.
The code test I'm using is yours, found here: viewtopic.php?f=8&t=42
The baud is 38400.
Any idea about how to solve this issue?

I was not aware about this issue. Probably it could be useful to write it in the main topic about Ferduino Mega on the forum. Just to inform people before that they buy probes and circuits. I'll try to sell the density circuit. I can spend more money on that.

[Fernando Garcia]

Default baud rate for EZO stamps is 9600. Have you changed it as explained in some topics here?

The isolation will be usefull to pH and ORP stamps too since pumps can produce electric noise as explained on datasheet. If your pumps is making noise you will get bad readings.

[Thomas di Maggio]

No, sorry. I didn't found this detail. can you give me a link to the right topic please?
Is there also a topic that explain the modification to do to Ferduino Mega to install your isolation circuit?

[Fernando Garcia]

viewtopic.php?p=1238#p1238

There no topic to explain it. You should only unsolder the multiplexer in your Ferduino Mega. Search here for 74HC4052 next of buzzer and stamps slots.

Warning: Should make this change only after make sure that your board is working fine with stamps otherwise will be hard to find any problem with isolation shield.

[Thomas di Maggio]

Great news! Modifying the Baud to 9600 everything works very well, both Ferduino code and test code.
I'll buy the isolation module from Christopher.

thank you so much.