US-100 Ultrasonic Ranging Module
HC-SR04 alternative with temperature compensation and optional UART mode for better consistency.
Wiring & code for
US 100 practical reference
A drop-in HC-SR04 upgrade that adds temperature compensation and an optional UART mode for more consistent readings. The US-100 uses the same physical dual-transducer layout as the classic HC-SR04, so it fits existing mounts and wiring, but internally it corrects for the fact that the speed of sound changes with air temperature — giving noticeably steadier distance readings across hot and cold environments — and it can optionally be switched into a simple 3-wire UART mode that skips the fussy pulse-timing of the standard trigger/echo interface entirely.
Key specifications
- Sensor type: Dual-transducer ultrasonic ranging module with onboard temperature compensation
- Operating voltage: 2.4V–5.5V DC
- Operating current: ~2.2 mA
- Measuring range: 2cm to 450cm
- Accuracy: ±1% typical, improved over standard HC-SR04 thanks to temperature compensation
- Interface modes: Trigger/Echo pulse mode (pin-compatible with HC-SR04) or UART serial mode, selectable by a jumper
- UART settings: 9600 baud, 8N1, when jumper-configured for serial mode
- Temperature sensor: Onboard temperature sensor used internally to correct the speed-of-sound calculation
Pinout and connection notes
A small onboard jumper (often a solder pad or physical switch) selects between classic trigger/echo pulse mode — wired and coded exactly like an HC-SR04 — and UART serial mode, which instead streams distance readings as simple serial bytes at 9600 baud, avoiding the need for precise pulse-width timing in your microcontroller code.
- VCC: Power, 2.4–5.5V DC
- Trig / TX: Trigger input in pulse mode, or UART TX in serial mode (set by onboard jumper)
- Echo / RX: Echo output in pulse mode, or UART RX in serial mode
- GND: Ground
Integration checklist
- Confirm the exact part number and breakout-board revision.
- Verify supply voltage, current demand, logic levels, and signal direction against the datasheet.
- Check controller pin assignments and bus address or interface mode against the example code.
- Power up with external loads disconnected, then test signals before full integration.
- If readings or communication fail, check power and ground first, then pin mapping, interface settings, and library initialization.
Troubleshooting and reproducibility
Record the board used, wiring, library/version, supply arrangement, and measured behavior. Use the selected board-specific wiring example as the source of truth. Never assume visually similar modules share identical voltage tolerance or pin order.