Data Logger Collecting Temperature, pH and Dissolved Oxygen with Timestamp

Schematics, Setup pH, DO boards

  • Switch to I2C mode for pH and DO circuits manually
  • SPI to I2C
    Set up manually the DO, pH for I2C mode

    The pH and DO breakouts are shipped with Serial communication as the default mode Transmit/Receive (TX/RX). To use the I2C mode Clock line (SCL), and Data line (SDA), switch mode by:

    1. un-plug VCC, TX, RX cables,
    2. jump TX to Ground for Probe, PGND (not GND), ,
    3. plug 5V power to the VCC in the circuit,
    4. wait for LED to change from Green to Blue.

    More details, please check on page 39 (Datasheet for pH circuit link here )

    To switch mode using the Serial Monitor, the code has to updated to the UNO/MEGA with the pH breakout connects in Serial mode then enter to Serial Monitor/Arduino IDE I2C,n, which n is an integer between 1-127, and for address of the pH breakout. The default is 99 (0x63). After that the wiring is redo in I2C mode.

  • Perform same steps with DO circuit
  • SD card to FAT format
  • It is backward after using high-speed USB stick with FAT32 or exFAT format and then working on the SD Card module. Use FAT16 is recommended. Consults this reference on for more. For Linux users, format SD card with FAT16 with sudo mkdosfs -F 16 /dev/sdb1 command and blkid for checking partitions mounted to the system.

    The SD module uses 5 wires (MISO, MOSI, SS, VCC, GND) and is faster than I2C. More details on these two modes are here. The designated pins for SPI mode on Arduino Mega and UNO/Nano are different.

    2.2 Wiring

    • Use jumper/DuPont cables to connect the parts as shown in the sketch below
    • Use the multimeter to check the conduction
    • Check the Positive-Voltage Supply (VCC) and Ground (GND). It is easy to confuse working back and forwward or not familiar with circuit
    • Plug in the power adapter and check the power indicator in each part. When in doubts, use the multi-meter to check the voltage between VCC and GND should be 5V
    Schematic of data logger
    Schematic of data logger.