Saturday, January 1, 2011

pHduino Datalogger shield released

Feliz Ano Novo!

De pHduino Datalogger

At the begin of the 2010, I developed a datalogger shield for the pHduino. Again, I decided to make something simple to mount, modify, and use. I put the project in stand by because I need improve the code. Yesterday, I resolved make the modifications and I released it today. You can download the hardware and firmware files from the page of the project.

The hardware

De pHduino Datalogger

The electronic circuit is based in two integrated circuits: an AT24C512 I2C EEPROM memory and a DS1307 I2C real-time clock (RTC). Additionally, there is a CR2032 battery and a 32kHz crystal for the RTC, a LED, two pull-up resistors, and a reset button.

Although 512kB, or 65536 bytes, is not a big memory, you can have some fun with it. For example, let's suppose you are decided storage the year (unsigned char), month (unsigned char), day (unsigned char), hour (unsigned char), minute (unsigned char), temperature (float), and the pH (float). You will spend 13 bytes with this block of data (unsigned char = 1 byte and float = 4 bytes). It is defined at the myRecLog_T struct, inside the pHduino datalogger code. 65536 byes divided by 13 bytes give us 5041 bocks of data. Using one block by minute is the same of 5041 minutes of acquisition or 84 hours or 3.5 days. Instead of it, you can acquire each 15 minutes (1260 hours or 52 days). You can, also, change the myRecLog_T struct to reduce the data block.

De pHduino Datalogger

The layout is a single side board. The circuit is very simple you can instead of to make the PCB, you can mount the circuit using a breadboard or a universal prototype board.

The firmware

The code is based on the pHduino firmware version 0.4.1. I added the code to control the EEPROM and the RTC. There is only one dependence: the RTC library. I decided to use the DS1307 library from the sjunnesson project.

The code will only store data when the pHduino code is in the start mode (cmd phduino start) and in the log mode (cmd log on).

The commands

It is simple to control. You can read the list of commands typing the command cmd help or reading the pHduino Datalogger wiki documentation.

I hope you enjoy it. Best 2011.


pHduino Project

pHduino Datalogger wiki documentation

pHduino files download

DS1307 library


  1. Hey, I like the project but i'm having trouble following this website. is there someplace to see how you did it and how much the parts cost. or pictures/video of the finished project actually working?

  2. Congratulations!!!! Very cool project Carlos! Robinson

  3. hello very good job, please tell me, how i run the programm ? you have include some libraries.who i put this libraries?

  4. Thank you. Could you open this discussion in the pHduino Discussion Group? There is a better place to discuss this and your doubts will be useful for the other users.

  5. sorry but i dont understand,where is the pHduino Discussion Group?


  7. Great ProJect carlos , im bulding one __

    in the eagle file i have a missing layer ? the grounds are mising ,


  8. The Eagle doesn't draw the ground plane at first. Press Ratsnest button.