PH-4502C pH sensor module with ESP32

Supply 5 V Bus ANALOG Measures ph

Pins and ESP32 wiring

Pin	Role	ESP32 pin	Notes
TO	Analog output	D34	Board temperature (not the liquid), optional
DO	Output (the part drives it)	D25	Threshold output, set by a trimmer. Its HIGH level is 5 V: use a voltage divider
PO	Analog output	D35	pH voltage, about 2.5 V at pH 7 after calibration, up to 5 V: use a voltage divider
GND1	Ground	GND	First G pin
GND2	Ground	GND	Second G pin
VCC	Power	VIN	Marked V+. Needs 5 V: use VIN

Suggested wiring for the 30-pin ESP32 DevKit, avoiding flash, input-only and strapping pins. BoardPilot checks it for you as you wire.

This module is sold for 5 V. Its outputs may be 5 V: use a level shifter or a voltage divider on ESP32 inputs.

void setup() { Serial.begin(115200); }

void loop() {
  int mv = analogReadMilliVolts(34);  // TO on GPIO 34
  Serial.println(mv);
  delay(200);
}

PH-4502C module seller sheet, Header To, Do, Po, G, G, V+; 5 V supply; BNC probe input
PH-4502C module seller sheet, Needs calibration with pH 4 and pH 7 buffer solutions

Part data: CC BY 4.0, free to reuse with credit to BoardPilot.