US-100 Ultrasonic Ranging Module
HC-SR04 alternative with temperature compensation and optional UART mode for better consistency.
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.
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
| Pin | Name | Description |
|---|---|---|
| 1 | VCC | Power, 2.4–5.5V DC |
| 2 | Trig / TX | Trigger input in pulse mode, or UART TX in serial mode (set by onboard jumper) |
| 3 | Echo / RX | Echo output in pulse mode, or UART RX in serial mode |
| 4 | GND | Ground |
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.
Variants
Use the US-100 as a near drop-in upgrade whenever an existing HC-SR04 project needs better accuracy across varying temperatures, or when you'd rather avoid pulse-timing code entirely by using its UART mode. Stick with the plain HC-SR04 for quick, low-stakes indoor projects where the extra accuracy isn't worth the small price difference.
| Variant | Temp range | Hum range | Accuracy | Protocol | Price |
|---|---|---|---|---|---|
| US-100 (pulse mode, HC-SR04 pin-compatible) | ~$2-4 | ||||
| US-100 (UART mode) | ~$2-4 | ||||
| HC-SR04 | ~$1-2 |