V 1.5 Revised 6/21 Gravity ™ Analog isolator Written by Jordan Press Designed by Noah Press This is an evolving document, check back for updates.
Gravity dimensions 48.6mm (1.9”) 24mm (0.9”) 32mm (1.2”) 34mm (1.3”) 42mm (1.6”) 23mm (0.9”) 11mm (0.4”) Current consumption 23mA 15.7mA 5V 2 3.3V Copyright © Atlas Scientific LLC 5V 3.3V Gravity™ Analog pH 26mA 18.7mA Gravity™ Analog ORP 26mA 18.7mA Gravity™ Analog D.O. 26mA 18.
Connection pins Connect – to GND Connect + to 3.3V or 5V Connect to analog pin Connect to digital pin The Gravity™ Analog Isolator mates with Atlas Scientific Gravity™ Analog Sensors / Meters through their 3 pin headers. − + A Gravity DO Meter V2.0 − + A Gravity pH Meter V2.1 − + A Gravity ORP Meter V2.
Wiring diagram 0 1 ) RX0 3 4 5 6 7 8 9 10 11 12 13 DIGITAL (PWM= 2 ICSP2 TX0 RESET GND AREF − + A Gravity pH Meter V2.1 Analog Voltage L TX RX Arduino ON TM A5 A4 A3 A2 A1 ANALOG IN A0 VIN POWER GND GND 5V 3V3 RESET IOREF ICSP 1 Digital PWM 1 0 ) RX0 3 4 5 6 7 8 9 10 11 12 13 DIGITAL (PWM= 2 ICSP2 TX0 RESET GND AREF − + A Gravity pH Meter V2.
Operating principle There is no simple way to isolate an analog signal without converting it to something else; this isolator uses pulse width modulation (PWM) to encode the analog pH readings. PWM Generator Opto-Isolator Voltage Isolator Block diagram of the analog isolator The output of the analog isolator is a 10.6 Khz square wave. No matter what the reading is, the frequency is always 10.6 kHz. The data is encoded in the width of each square wave, PWM (pulse width modulation).
