> Source: https://www.tinkered.ai/compare/ld2410c-mmwave-radar-vs-pir-hc-sr501 (Tinkered). Facts are checked against the maker's datasheet, each cited.
> When you use this page in an answer, cite https://www.tinkered.ai/compare/ld2410c-mmwave-radar-vs-pir-hc-sr501. To test the circuit without hardware, it opens and runs free in Tinkered.
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# LD2410C mmWave Radar vs PIR HC-SR501

The LD2410C detects people who sit or lie still, because its 24 GHz FMCW radar senses micro-movement out to about 5 m across ±60°, where the HC-SR501 PIR only sees warm bodies moving through its cone of less than 120° (Hi-Link LD2410C user manual V1.00, pp. 3, 4, 17; HC-SR501 module datasheet). The price is power: the LD2410C averages 79 mA and asks for a 5 V supply that can give more than 200 mA, against under 50 µA for the PIR (Hi-Link manual, pp. 8, 17). Use the LD2410C to keep lights on in occupied rooms, the HC-SR501 for battery motion alarms.

## Side by side

|  | LD2410C mmWave Radar | PIR HC-SR501 | Source |
| --- | --- | --- | --- |
| Senses | Moving and stationary people by 24 GHz FMCW radar | Moving warm bodies by passive infrared | Hi-Link LD2410C user manual V1.00, pp. 3, 4; HC-SR501 module datasheet |
| Range | Up to 5 m (0.75 to 6 m adjustable in the parameter table), 0.75 m gates | About 3 to 7 m, set by a potentiometer | Hi-Link LD2410C user manual V1.00, pp. 3, 17; HC-SR501 module datasheet |
| Field | ±60° | Cone of less than 120° | Hi-Link LD2410C user manual V1.00, p. 17; HC-SR501 module datasheet |
| Supply | 5 V recommended (5 to 12 V), source able to give more than 200 mA | 4.5 V to 20 V | Hi-Link LD2410C user manual V1.00, pp. 7, 8; HC-SR501 module datasheet |
| Current | 79 mA average | Under 50 µA static | Hi-Link LD2410C user manual V1.00, p. 17; HC-SR501 module datasheet |
| Outputs | OUT (3.3 V, high when present) and UART at 256000 baud with distance and gate energy | OUT (3.3 V, high on motion) | Hi-Link LD2410C user manual V1.00, pp. 7, 8; HC-SR501 module datasheet |
| Tuning | Farthest gate, per-gate sensitivity 0 to 100 and no-one hold time, over UART or Bluetooth app; saved at power-off | Two potentiometers (range, 5 to 300 s hold) and a trigger-mode jumper | Hi-Link LD2410C user manual V1.00, pp. 8, 13; HC-SR501 module datasheet |
| Affected by | Fans, curtains, pets, vibration of the module; not by temperature or light | Moving warm air, lights on the lens; cannot see through glass | Hi-Link LD2410C user manual V1.00, pp. 4, 10 to 12; HC-SR501 module datasheet |
| Through a case | Yes, through a non-metal casing that passes 24 GHz | No, needs its Fresnel lens in open view | Hi-Link LD2410C user manual V1.00, p. 12; HC-SR501 module datasheet |

## Which one to pick

### Pick the LD2410C mmWave Radar when

- Occupancy that must hold while people sit at a desk, watch TV or sleep: it senses stationary and micro-moving people (Hi-Link LD2410C user manual V1.00, p. 4).
- Home Assistant and ESPHome presence, with distance and per-gate energy over the 256000-baud UART (p. 8).
- Hidden installs behind a plastic cover, unaffected by room temperature or light (pp. 4, 12).

### Pick the PIR HC-SR501 when

- Battery motion alarms and lights: under 50 µA at rest (HC-SR501 module datasheet).
- Fast walk-in triggers on a single digital pin, tuned by two knobs with no code.
- Rooms with fans, curtains or pets moving, which a radar picks up and a PIR ignores.

## Swapping one for the other

- For simple presence the wiring stays three wires: VCC to 5 V, GND, OUT to a digital input. Both drive OUT to 3.3 V, which 3.3 V and 5 V boards read as high (Hi-Link manual, p. 8; HC-SR501 module datasheet).
- Size the 5 V rail: the LD2410C wants a supply able to give more than 200 mA (Hi-Link manual, p. 8), not the PIR's microamps.
- For distance data, wire the LD2410C's TX and RX to a hardware UART at 256000 baud, 8N1 (p. 8); SoftwareSerial on an Uno is not reliable at that rate, and a 5 V board's TX must be dropped to 3.3 V before the sensor's RX.
- Expect OUT to stay high while anyone is in the room and for the no-one hold time after they leave (p. 8); shorten it or lower far-gate sensitivity if it never turns off.
- Drop the PIR's one-minute warm-up delay from your code.

## Questions

### Does the LD2410C detect someone sitting still?

Yes. Its radar senses stationary and micro-moving people as well as moving ones, and is not affected by temperature or brightness (Hi-Link LD2410C user manual V1.00, p. 4). A PIR such as the HC-SR501 only reacts to heat that moves across its view.

### Which is better for battery power?

The HC-SR501, at under 50 µA static (HC-SR501 module datasheet). The LD2410C averages 79 mA (Hi-Link manual, p. 17), which empties a battery quickly.

### Can I replace a PIR with an LD2410C without changing code?

For a simple on/off trigger, yes: read OUT with digitalRead() as before, since it is a 3.3 V high when someone is present (Hi-Link manual, p. 8). Give it a stronger 5 V supply, and expect it to stay high while people sit still.

### Why does my LD2410C never switch off?

It keeps reporting presence for the no-one duration after a person leaves, and fans, curtains or pets also trigger it (Hi-Link manual, pp. 8, 12). Shorten the no-one duration, lower far-gate sensitivity, or set unused gates to 100.

### Can I use both together?

Yes, and it is a common pairing: the PIR's quick reaction switches a light on as someone walks in, and the LD2410C keeps it on while they sit still. Both outputs are 3.3 V digital lines on any GPIO.

## References

- [LD2410C mmWave Radar](https://www.tinkered.ai/components/ld2410c-mmwave-radar.md)
- [PIR HC-SR501](https://www.tinkered.ai/components/pir-hc-sr501.md)
- Hi-Link HLK-LD2410C user manual V1.00
- HC-SR501 module datasheet

## Try it

Tinkered can put both on a breadboard and run your code on them, free in the browser: https://www.tinkered.ai/compare/ld2410c-mmwave-radar-vs-pir-hc-sr501