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Topic: Adding pH and temperature (and date and time) to existing sketch (Read 1 time) previous topic - next topic


Hello everyone,

This project sounds simple from the ground up but has me stuck being thrown in halfway i.e. with an already written complex sketch (attached).

We have a vessel which has liquid in which we want to monitor (temp and pH) over time. The vessel currently has:

a)   A heat jacket- which wraps around the vessel which the user can set the temperature of using buttons on the front a "control box" - which gets feedback from b) the NTC probe
b)   NTC (Temperature probe) - which measures the temperature of the liquid in the vessel and currently outputs to an LCD screen (and provides feedback for the heat jacket to turn on/off)
c)   pH probe - which measures the pH of the liquid in the vessel and which can be calibrated using the buttons on the front and currently outputs to an LCD screen. (and provides input for a pump to pump acid/base into the vessel to turn on/off)

All this is working fineā€¦

All I need to do is data log the pH and temperature of the liquid over time (every 30sec or so- using a RTC3231) onto an SD card shield.

Im also not sure if an Uno will have all the necessary I/O for this.

It sounds simple! But dont know what code to put in where, and frankly what extra wires to put in where... This is where I shout HELP!     HELP, please! :smiley-confuse:


The first step is to determine whether the pH meter and the temperature controller have interfaces for output of data to external loggers. Many don't.

If they do, you need to know the ALL details of the data output stream: type of interface, voltages, speed, encoding, etc. before you can consider connecting an Arduino.



Im also not sure if an Uno will have all the necessary I/O for this.
You simply need pins A4,A5 for the clock, and pins 11,12,13 plus one other for the SD, many of which may already be vacant, so you probably have enough I/O for this, and don't forget that the analogue pins may be used as digital. If your LCD is on any of the abovementioned pins, it can share them anyway.

You are far more likely to run out of memory first, so be prepared to replace the Uno with a Mega.


@jremington - sorry if my post is not clear or I misunderstand, both the pH & NTC probe are connected to an Uno (and hence the pH  can be  displayed (and calibrated) and the NTC probe can provide data a) to the LCD b) to adjust the heat jacket).

@wildbill - yes we have an RTC and the SD card shield (and microSD card)

@Nick_Pyner -  awesome thanks, that should sort the wiring and gives me hope our Uno will work

This gives me hope that its possible :) I am just stuck on the programming/sketch


As ever, just write a sketch for each piece of hardware so you can prove to yourself that you can get them working. Then graft that code (one by one) into the main program.

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