Hardware Compatibility

Complete compatibility information for Arduino boards and ultrasonic sensors.

Supported Arduino Boards

Fully Compatible

Board	Clock	RAM	Flash	GPIO	Status
Arduino Uno	16 MHz	2 KB	32 KB	5V	✅ Tested
Arduino Nano	16 MHz	2 KB	32 KB	5V	✅ Tested
Arduino Mega 2560	16 MHz	8 KB	256 KB	5V	✅ Tested
Arduino Leonardo	16 MHz	2.5 KB	32 KB	5V	✅ Compatible
Arduino Micro	16 MHz	2.5 KB	32 KB	5V	✅ Compatible
Arduino Pro Mini	16 MHz	2 KB	32 KB	5V	✅ Compatible

Compatible with Voltage Conversion

Board	Clock	RAM	GPIO Logic	Requires
Arduino Due	84 MHz	96 KB	3.3V	Level shifter
Arduino Zero	48 MHz	32 KB	3.3V	Level shifter
Arduino MKR1000	48 MHz	32 KB	3.3V	Level shifter
ESP32	240 MHz	320 KB	3.3V	Level shifter
ESP8266	80 MHz	80 KB	3.3V	Level shifter
Teensy 3.x	72-180 MHz	64-256 KB	3.3V	Level shifter
Teensy 4.x	600 MHz	512 KB-1 MB	3.3V	Level shifter

Not Recommended

Board	Issue	Workaround
Arduino 101	Different architecture	Use native libraries
Arduino Yún	Limited GPIO	Use standard pins only
Gemma/Trinket	Limited pins	Use 3-pin mode

Supported Sensors

HC-SR04 (Primary)

Specifications:

Voltage: 5V DC
Current: 15mA (peak), 2mA (idle)
Range: 2cm - 400cm
Accuracy: ±3mm
Angle: 15° effective
Frequency: 40kHz
Trigger: 10µs pulse
Echo: Pulse width proportional to distance

Pinout:

txt

┌─────────────────┐
│  HC-SR04        │
│                 │
│  ┌───┐   ┌───┐ │
│  │ T │   │ R │ │ T = Transmitter
│  └───┘   └───┘ │ R = Receiver
│                 │
│ VCC GND TRG ECH │
└──┬──┬───┬───┬──┘
   │  │   │   └── Echo (output)
   │  │   └────── Trigger (input)
   │  └────────── Ground
   └───────────── 5V power

Wiring:

cpp

// 4-pin mode (recommended)
VCC  → 5V
GND  → GND
TRIG → Digital Pin 7
ECHO → Digital Pin 8

// 3-pin mode (shared trigger/echo)
VCC  → 5V
GND  → GND
TRIG → Digital Pin 7
ECHO → Digital Pin 7 (via 1kΩ resistor)

Code:

cpp

// 4-pin
MinimalUltrasonic sensor(7, 8);

// 3-pin
MinimalUltrasonic sensor(7);

Ping))) (Parallax)

Specifications:

Voltage: 5V DC
Current: 35mA (peak), <2mA (idle)
Range: 3cm - 300cm
Accuracy: ±1cm
Angle: 45° wide beam
Frequency: 40kHz
Single pin: Combined trigger/echo

Pinout:

txt

┌─────────────┐
│   Ping)))   │
│             │
│    ┌───┐    │
│    │ o │    │ Transducer
│    └───┘    │
│             │
│ GND  SIG  V+│
└──┬────┬───┬─┘
   │    │   └─── +5V
   │    └─────── Signal (I/O)
   └──────────── Ground

Wiring:

cpp

GND → GND
SIG → Digital Pin 7
V+  → 5V

Code:

cpp

// Use 3-pin mode (shared trigger/echo)
MinimalUltrasonic sensor(7);

Seeed Studio Ultrasonic Ranger

Specifications:

Voltage: 3.3-5V DC
Current: 20mA (peak)
Range: 3cm - 400cm
Accuracy: ±1cm
Angle: 15° beam
Frequency: 42kHz
Single pin: Combined trigger/echo

Pinout:

txt

┌─────────────┐
│ Seeed       │
│ Ultrasonic  │
│             │
│ VCC SIG GND │
└──┬───┬───┬──┘
   │   │   └─── Ground
   │   └─────── Signal (I/O)
   └─────────── 3.3-5V power

Wiring:

cpp

VCC → 5V (or 3.3V)
SIG → Digital Pin 7
GND → GND

Code:

cpp

MinimalUltrasonic sensor(7);

HY-SRF05

Specifications:

Voltage: 5V DC
Current: 15mA
Range: 2cm - 450cm
Accuracy: ±3mm
Mode 1: Separate trigger/echo (like HC-SR04)
Mode 2: Single pin (OUT pin unconnected)

Wiring:

Mode 1 (4-pin):

cpp

VCC  → 5V
GND  → GND
TRIG → Digital Pin 7
ECHO → Digital Pin 8
OUT  → Leave unconnected

MinimalUltrasonic sensor(7, 8);

Mode 2 (3-pin):

cpp

VCC  → 5V
GND  → GND
TRIG → Digital Pin 7
ECHO → Leave unconnected
OUT  → Leave unconnected

MinimalUltrasonic sensor(7);

US-100

Specifications:

Voltage: 5V DC (also 3.3V)
Current: 20mA
Range: 2cm - 450cm
Accuracy: ±3mm
Modes: Ultrasonic or UART
Temperature sensor: Optional

Ultrasonic Mode (Jumper removed):

cpp

VCC  → 5V
GND  → GND
TRIG → Digital Pin 7
ECHO → Digital Pin 8

MinimalUltrasonic sensor(7, 8);

Note: Remove jumper for ultrasonic mode. With jumper, uses UART (not compatible with this library).

Voltage Level Conversion

Why Needed

HC-SR04 requires 5V logic:

Input (Trigger): Needs 5V HIGH
Output (Echo): Outputs 5V HIGH

3.3V boards (ESP32, Due, etc.):

Output: Only 3.3V HIGH (may not trigger HC-SR04)
Input: 5V can damage GPIO (max 3.3V)

Level Shifter Solutions

Option 1: Bidirectional Level Shifter (Best)

txt

3.3V Board          Level Shifter       HC-SR04
──────────         ───────────────      ─────────
      
3.3V ─────────────── LV              
                     HV ─────────────── 5V
                                    
Pin 7 ──────────────── A1              
(Trig)               B1 ─────────────── TRIG
                                    
Pin 8 ──────────────── A2              
(Echo)               B2 ─────────────── ECHO
                                    
GND ─────────────────GND─────────────── GND

Products:

Adafruit BSS138 (4-channel)
SparkFun BOB-12009 (4-channel)
Generic 4-channel MOSFET shifter

Option 2: Voltage Divider (Echo only)

txt

HC-SR04              3.3V Board
────────             ──────────

ECHO ────┬───────────── Pin 8
         │
        ┌┴┐
        │ │ 1kΩ
        └┬┘
         ├───────────── Pin 7 (Trig)
        ┌┴┐
        │ │ 2kΩ
        └┬┘
         │
        GND

Math:

txt

V_out = V_in × R2 / (R1 + R2)
V_out = 5V × 2kΩ / (1kΩ + 2kΩ)
V_out = 3.33V

Limitations:

Echo protection only
Trigger may not reach 5V (HC-SR04 might work with 3.3V trigger, depends on module)

Option 3: Dedicated 5V Supply + Level Shifter

Best for ESP32/ESP8266:

txt

Power Supply         ESP32            HC-SR04
────────────        ───────          ─────────
                    
5V ─────────┬─────── VIN (if present)
            └────────────────────── VCC
                                
3.3V ─────────────── LV (Shifter)
                                
5V ─────────────────── HV (Shifter)
                                
GND ────────┴────────────────────── GND

Pin Requirements

GPIO Pin Selection

Any digital pins work, but consider:

Avoid PWM pins if using PWM elsewhere
- Uno: 3, 5, 6, 9, 10, 11
- Mega: 2-13, 44-46
Avoid I2C pins if using I2C
- Uno: A4 (SDA), A5 (SCL)
- Mega: 20 (SDA), 21 (SCL)
Avoid SPI pins if using SPI
- Uno: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK)
- Mega: 50 (MISO), 51 (MOSI), 52 (SCK), 53 (SS)
Avoid Serial pins if using Serial
- Uno: 0 (RX), 1 (TX)
- Mega: 0/1 (Serial), 14-19 (Serial1-3)

Recommended pins for Uno:

cpp

// Good choices (no special functions):
Pin 2, 4, 7, 8

// Example:
MinimalUltrasonic sensor(7, 8);

Recommended pins for Mega:

cpp

// Plenty of options, example:
MinimalUltrasonic sensor(22, 23);

3-Pin vs 4-Pin Mode

4-Pin Mode (Recommended):

cpp

MinimalUltrasonic sensor(7, 8);

Advantages:
✅ Simpler wiring (no resistor)
✅ Clearer pin usage
✅ Works with all sensors

Disadvantages:
❌ Uses 2 GPIO pins

3-Pin Mode:

cpp

MinimalUltrasonic sensor(7);

Advantages:
✅ Saves 1 GPIO pin
✅ Required for Ping))) sensors

Disadvantages:
❌ Needs resistor (HC-SR04)
❌ More complex wiring

Power Requirements

Current Draw

Per sensor:

txt

State           | Current
----------------|--------
Idle            | 2 mA
During ping     | 15 mA (HC-SR04)
                | 35 mA (Ping)))
                | 20 mA (Others)
Average @ 1Hz   | ~2 mA
Average @ 10Hz  | ~3 mA
Average @ 50Hz  | ~5 mA

Multiple sensors:

txt

Sensors | Peak Current | Safe Supply
--------|--------------|-------------
1       | 15 mA        | 50 mA
2       | 30 mA        | 100 mA
5       | 75 mA        | 150 mA
10      | 150 mA       | 300 mA

Arduino power limits:

USB power: 500 mA total
5V pin: 500 mA max (via USB)
5V pin: 800 mA max (via barrel jack, depends on regulator)
Per GPIO: 40 mA max

Power Supply Options

Option 1: Arduino 5V Pin (Small projects)

cpp

// 1-3 sensors, fine
VCC → Arduino 5V pin
GND → Arduino GND

Option 2: External 5V Supply (Many sensors)

cpp

// 4+ sensors, recommended
VCC → External 5V supply (+)
GND → External GND (-) AND Arduino GND (common ground!)

Option 3: Separate Regulator

cpp

// Best for >10 sensors
Battery → 7805 regulator → Sensors VCC
                          → Arduino VIN
         Common GND ─────────────────

Compatibility Issues

Common Problems

Problem 1: 3.3V board with HC-SR04

txt

Symptom: No readings or sporadic readings
Cause: Voltage mismatch
Solution: Use level shifter

Problem 2: Insufficient power

txt

Symptom: Readings drop out, sensor resets
Cause: Current draw exceeds supply
Solution: External power supply

Problem 3: GPIO conflicts

txt

Symptom: Sensor or other device stops working
Cause: Pin used by multiple peripherals
Solution: Use different pins

Problem 4: Shared ground missing

txt

Symptom: Erratic behavior with external power
Cause: Arduino and sensor don't share GND
Solution: Connect GNDs together

Problem 5: Crosstalk (multiple sensors)

txt

Symptom: Incorrect readings with multiple sensors
Cause: Ultrasonic interference
Solution: Time-multiplex or space sensors apart

Testing Compatibility

Quick Test Sketch

cpp

#include <MinimalUltrasonic.h>

MinimalUltrasonic sensor(7, 8);

void setup() {
    Serial.begin(9600);
    Serial.println("MinimalUltrasonic Compatibility Test");
    Serial.println("====================================");
    
    // Board info
    Serial.print("Board: ");
    #if defined(__AVR_ATmega328P__)
        Serial.println("Arduino Uno/Nano");
    #elif defined(__AVR_ATmega2560__)
        Serial.println("Arduino Mega");
    #elif defined(__AVR_ATmega32U4__)
        Serial.println("Arduino Leonardo/Micro");
    #elif defined(ESP32)
        Serial.println("ESP32");
    #elif defined(ESP8266)
        Serial.println("ESP8266");
    #else
        Serial.println("Unknown");
    #endif
    
    // Sensor test
    Serial.println("\nSensor test (10 readings):");
    int successes = 0;
    
    for (int i = 0; i < 10; i++) {
        unsigned int dist = sensor.read();
        
        if (dist > 0) {
            successes++;
            Serial.print("✓ ");
        } else {
            Serial.print("✗ ");
        }
        
        Serial.print(dist);
        Serial.println(" cm");
        
        delay(100);
    }
    
    Serial.println("\n====================================");
    Serial.print("Success rate: ");
    Serial.print(successes * 10);
    Serial.println("%");
    
    if (successes >= 8) {
        Serial.println("✅ Fully compatible");
    } else if (successes >= 5) {
        Serial.println("⚠️ Marginal - check wiring/power");
    } else {
        Serial.println("❌ Incompatible - check voltage levels");
    }
}

void loop() {}

Expected Results

Fully compatible (Uno, Nano, Mega with HC-SR04):

txt

Success rate: 90-100%
✅ Fully compatible

Needs level shifter (ESP32 with HC-SR04, no shifter):

txt

Success rate: 0%
❌ Incompatible - check voltage levels

Power issues:

txt

Success rate: 30-70%
⚠️ Marginal - check wiring/power

Hardware Compatibility ​

Supported Arduino Boards ​

Fully Compatible ​

Compatible with Voltage Conversion ​

Not Recommended ​

Supported Sensors ​

HC-SR04 (Primary) ​

Ping))) (Parallax) ​

Seeed Studio Ultrasonic Ranger ​

HY-SRF05 ​

US-100 ​

Voltage Level Conversion ​

Why Needed ​

Level Shifter Solutions ​

Pin Requirements ​

GPIO Pin Selection ​

3-Pin vs 4-Pin Mode ​

Power Requirements ​

Current Draw ​

Power Supply Options ​

Compatibility Issues ​

Common Problems ​

Testing Compatibility ​

Quick Test Sketch ​

Expected Results ​

See Also ​

Hardware Compatibility

Supported Arduino Boards

Fully Compatible

Compatible with Voltage Conversion

Not Recommended

Supported Sensors

HC-SR04 (Primary)

Ping))) (Parallax)

Seeed Studio Ultrasonic Ranger

HY-SRF05

US-100

Voltage Level Conversion

Why Needed

Level Shifter Solutions

Pin Requirements

GPIO Pin Selection

3-Pin vs 4-Pin Mode

Power Requirements

Current Draw

Power Supply Options

Compatibility Issues

Common Problems

Testing Compatibility

Quick Test Sketch

Expected Results

See Also