It’s built on an Atmega32u4 with a modified Arduino Leonardo (thus the leo in the name?) bootloader. Environmental parameters are gathered through a pH sensor, an LM335A temperature sensor and an analog humidity sensor. The analog signal from the pH sensor goes through an offset introducing fixed gain op-amp circuit that centers the signal into the range of the Atmega32u4′s Analog to Digital Converter (ADC) Pins. The parameters are then printed out into a four liner Liquid crystal display (LCD).
This project also has calibration routine and when used with a computer you can send commands to set the LeoPhi into specific modes. Click on the read more below to see the command list.
- C – Continous Read Mode: Dump readings and data every second
- R – Single pH reading: response “pH: XX.XX” where XX.XX is the pH
- E – Exit continuous read mode
- S – set pH7 Calibration point
- F – set pH4 Calibration point: also recalcs probe slope and saves settings to EEPROM
- T – set pH10 Calibration point: also recalcs probe slope and saves settings to EEPROM
- X – restore settings to default and ideal probe conditions