Actual distance = Measured distance * (343.0 / sqrt(331.3 * (1 + T_celsius/273.15))) | Parameter | Conditions | Value | |-----------|------------|-------| | Supply voltage | Absolute max | 5.5V | | Supply voltage | Operating | 4.5V – 5.5V | | Logic input low | Trig, EN | < 0.8V | | Logic input high | Trig, EN | > 2.0V (3.3V compatible) | | Echo output low | IOL = 2mA | < 0.4V | | Echo output high | IOH = 2mA | > 4.0V (5V logic) | | Output impedance | - | 100 Ω |
delay(60);
| Pin | Name | Function | |-----|------|-----------| | 1 | VCC | +5V DC (regulated) | | 2 | Trig | Trigger input (active high, 10 µs min pulse) | | 3 | Echo | Echo output (PWM width = time of flight) | | 4 | GND | Ground | aj sr04m datasheet
void loop() digitalWrite(TRIG, LOW); delayMicroseconds(2); digitalWrite(TRIG, HIGH); delayMicroseconds(10); digitalWrite(TRIG, LOW);
while GPIO.input(ECHO) == 0: pulse_start = time.time() while GPIO.input(ECHO) == 1: pulse_end = time.time() Actual distance = Measured distance * (343
Some versions have a 5th pin (EN – Enable), but standard 4-pin is most common. If present, tie EN to VCC to enable. Wiring Example (Arduino): AJ-SR04M → Arduino Uno VCC → 5V Trig → Digital Pin 9 Echo → Digital Pin 10 GND → GND 3. Theory of Operation & Timing Diagram The AJ-SR04M uses the same timing protocol as HC-SR04, but with improved signal conditioning for longer cable runs.
1. Overview & Key Differentiators The AJ-SR04M is an improved, industrial-grade variant of the popular HC-SR04. Unlike the standard HC-SR04, this module is enclosed in a waterproof, IP67-rated housing , making it suitable for outdoor, dusty, or humid environments (e.g., tank level sensing, outdoor robotics, car reverse sensors). Theory of Operation & Timing Diagram The AJ-SR04M
def get_distance(): GPIO.output(TRIG, False) time.sleep(0.05) GPIO.output(TRIG, True) time.sleep(0.00001) GPIO.output(TRIG, False)