TODOs

Open Q's

• Calibration must happens when probe is switched. When and how to do this?
• Is it worth disabling the EZO circuit LED?
  • Perhaps sending the command takes more power than the LED being on

Atlas Scientific EZO Circuit

• Send probe K value from EEPROM in perform_measurement
• Send calibration string from EEPROM in perform_measurement
• Send water temperature from EEPROM in perform_measurement