Sunday, September 20, 2009

pHduino Firmware v04 released

Again, one more pHduino firmware release. Two main features: pH alarm, to warn when the pH is out of the normal range, and save parameters in the Arduino EEPROM memory, to recover the last configuration after a reset or a power off.

Changelog v04_20090920
  • Changed file name from phduino.h to pHduino.h.
  • Added codename version.
  • Added function to set the pH range for the pH alarm. 
  • Added pH alarm signals: LED, beeps, message by serial port and LCD.
  • Added feature to save parameters in the EEPROM memory of the Arduino board.
  • Added function to reset parameters in the EEPROM.
This is the newest list of commands.

cmd help
cmd phduino start|stop
cmd interval_ms INT
cmd set_temp_sensor on|off
cmd set_temp FLOAT
cmd set_ph_alarm TEMP_INF TEMP_SUP
cmd ph_alarm on/off
cmd reset

The code still fits in an Atmega168.

If you are using the pHduino in some project, send me the link to make a post about your project. I will really appreciate post a list of links about related projects.




  1. I am very new to the world of microcontrollers and electronics, I was wondering, will I be able to use the digital output pins still for other uses or will they be taken up now?

    Also, are you planning on selling etched PCB? I can buy most of the other components if you have a list of them.

  2. Sorry again about the delay.

    Yes, of course. With this layout there are two digital lines not used (2 and 3). But, someone with some experience with Arduino code can remove the LCD code for only serial communication, for example. Another suggestion is a serial LCD.

    In this moment, I am very busy with my research job. I am studing a way to sell the PCB, but I need check the licenses about the Eagle and discover a good seller.

  3. The place I was going to use for the PCB ended up stating that the spaces between the traces are too small. They need to be at least 8mil apart.

  4. What is the control button for? I didn't see any mention of its use in the firmware. Did you just put it in there incase someone wanted to use a button?

  5. Yes. I don't have an application for it by know. In case, it is there.

  6. Hey Carlos,
    I'm currently working on a project that implements similarities to your pHduino, and I've actually used a modified version of your pH metering circuit.

    My project basically measures pH, temperature, and level of water in a tank I have built. The user inputs a setpoint value for pH, and I am creating a system that will automatically correct pH to this setpoint using a servo system that releases corrective chemicals into the water.
    The whole system is also based around the Arduino Duemilanove.
    I'd much appreciate your help, you seem like you really know what you're doing! I don't really know much about chemistry, or how stable pH is, nor do I know much about the calibration of the probe.

    Send an e-mail my way, and I'll give you lots of info on my project!

    seekaewai at

  7. Hi,

    I suggest you enter in the pHduino group discussion at the Google Groups.

  8. Hi Carlos, Any news on selling the pHduino yet, I really want this for full automation of my bio diesel processing plant, the pHduino will eliminate the need for titration to find out how much catalyst is needed to convert the raw oil into glycerine and methyl esters. Hope you can get this out ASAP!!!! has a program been written to export digital data to another arduino for process control?
    thanks for your time,


  9. Hi Jay,

    Unfortunately, I can sell it, because I used the Eagle Free to make the PCB. I am planning make a new circuit with improvements, using a free EDA software, and start a PCB production.

    About the control, I did not another software because I do not need control another circuit.

    Please, I suggest you enter in the discussion group at the Google Groups. Your problem could be useful for other users.