RPLIDAR A1 (A1M8): specs and pinout
Slamtec 2D laser triangulation scanner that spins 360 degrees and reports distance and angle over a 3.3 V UART. The motor and the scanner core have separate supply pins.
Specs
| Spec | Value | Source |
|---|---|---|
| Distance range (white objects) | 0.15 m to 12 m | source p.8 Figure 2-1 |
| Sample frequency | 8000 Hz typ (8010 Hz max) | source p.8 Figure 2-1 |
| Scan rate | 5.5 Hz typ (1 Hz min, 10 Hz max) | source p.8 Figure 2-1 |
| Angular resolution | 1 degree at 5.5 Hz scan rate | source p.8 Figure 2-1 |
| Distance resolution | under 0.5 mm below 1.5 m; under 1 % of the distance over the full range | source p.8 Figure 2-1 |
| Laser | 785 nm infrared, Class I, under 5 mW | source pp.5 and 9 Figure 2-3 |
| Scanner core supply | 4.9 V to 5.5 V (5 V typ); low ripple, under 1 %; above 5.5 V may damage the core | source p.11 Figures 2-7 and 2-8; p.10 Figure 2-6 |
| Scanner core supply ripple | 20 mV typ, 50 mV max; high ripple may cause core failure | source p.11 Figure 2-8 |
| Scanner core current | 300 mA typ / 350 mA max working; 80 mA typ / 100 mA max sleep; 600 mA max at start-up | source p.11 Figure 2-8 |
| Motor supply and current | 5 V to 9 V (adjust to speed); about 100 mA at 5 V. For scan rates from 5.5 Hz to 10 Hz Slamtec says to supply 9 V to the motor separately | source p.11 Figure 2-8; p.3 note under Figure 1-1 |
| Serial interface | 3.3 V TTL UART, 115200 baud, 8N1 | source p.9-10 Figure 2-5 |
| Operating temperature | 0 C to 40 C | source p.12 Figure 2-9 |
| Weight | 170 g typ | source p.12 Figure 2-9 |
Power
| Value | Source | |
|---|---|---|
| Supply | Scanner core 4.9 V to 5.5 V, low ripple (50 mV max); motor 5 V to 9 V. Slamtec says the two are powered separately | source p.11 Figures 2-7 and 2-8 |
| Current | Core 300 mA typ / 350 mA max working, 600 mA max at start-up; motor about 100 mA at 5 V | source p.11 Figures 2-7 and 2-8 |
Pinout
Signals are from the Slamtec A1M8 data sheet (motor interface PH1.25-3P, core interface PH1.25-4P on the batch version). The development kit adds a USB adapter board with a separate 7-pin interface; the listing does not say which is supplied.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| 5V_MOTO | Power for the motor | Typ 5 V, max 9 V (motor interface) | source p.10 Figure 2-6 | |
| CTRL_MOTO | Motor enable / PWM control input | 0 V to 5V_MOTO (motor interface) | source p.10 Figure 2-6 | |
| GND_MOTO | Ground for the motor | 0 V | source p.10 Figure 2-6 | |
| VCC_5 | Power for the range scanner core | 4.9 V min, 5 V typ, 5.5 V max | source p.10 Figure 2-6 | |
| TX | Serial output of the range scanner core | 3.3 V TTL UART (Figure 2-5) | source p.10 Figure 2-6 | |
| RX | Serial input of the range scanner core | 3.3 V TTL UART (Figure 2-5) | source p.10 Figure 2-6 | |
| GND | Ground for the range scanner core | 0 V | source p.10 Figure 2-6 |
Build with it
Project ideas for the RPLIDAR A1 (A1M8). Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- Room scan viewer on a Raspberry Pi: Slamtec provides SDKs for ARM Linux. Slamtec powers the scanner core (4.9-5.5 V, low ripple, 600 mA at start-up) and the motor (5-9 V, about 100 mA at 5 V) as separate systems. Supply parts: the Pi runs from the stocked USB-C 5 V adapter; the scanner core from the stocked 5 V 2 A adapter, not shared with the Pi; the motor from a separate 5 V supply of the same kind at the default speed. Check the core ripple against the 50 mV limit. Scanning shared spaces: tell people present. Learning project.
- Nearest-object read-out on an ESP32: The ESP32 UART is 3.3 V, matching the scanner; power the ESP32 from its own USB supply. Two 18650 cells in series (about 6 to 8.4 V) feed two buck converters: the fixed 5 V module for the scanner core (600 mA start-up peak) and the Mini-360 set to 5 V for the motor (about 100 mA). Buck converters only step down, so the pack must stay above each converter's minimum input; check each module's input range. Slamtec asks for under 50 mV ripple on the core supply, so measure it. The serial protocol comes from Slamtec. Learning project.
- A battery powered laser scanner rig with an RPLIDAR A1, a Raspberry Pi 4, a 5 volt converter and a 9 volt buck-boost converter: A three-cell pack runs from about 12.6 V full to about 9 V or lower when empty. The fixed 5 V buck module feeds the scanner core. A plain buck cannot hold 9 V near the bottom of that range, so the motor's 9 V (which Slamtec says is needed for scan rates from 5.5 Hz to 10 Hz) comes from the stocked 5 A synchronous buck-boost converter, set to 9 V with a meter before connecting the scanner; check its input range on the module. The Pi keeps its own supply. Check the core ripple (50 mV max) before connecting the scanner. Learning project.
Common mistakes
- Using a weak or noisy 5 V source for the core: it can draw up to 600 mA at start-up, under-power may cause start-up failure and high ripple may cause core failure (source: link, p.11 Figure 2-8)
- Wiring the UART to a 5 V logic board: the interface is 3.3 V TTL and input high is specified up to 3.5 V (Figure 2-5; Figure 2-6 lists 5 V, so stay at 3.3 V) (source: link, p.10)
- Using it in direct sunlight: the data sheet says it works indoors and outdoors without direct sunlight (source: link, p.3 and p.6)
Not covered by the official source
- Data sheet Figure 2-5 gives 3.5 V max input high on the UART while Figure 2-6 lists 5 V for TX/RX; the page recommends 3.3 V logic.
- The serial protocol and SDK are separate Slamtec downloads and are not given on this page.
- Listing does not say whether the USB adapter board and cable are included.
- Slamtec's download list now shows a datasheet labelled 3.2; the values here are from the rev 3.0 (2020-10-15) copy and the newer file was not checked.
- The development kit's USB adapter board may join the core and motor supplies; its schematic is not covered here, so the supplies above apply to the bare scanner pins.
- Per-field source URLs end in /3.2 because that is the only download link Slamtec lists; no /3.0 link is published, and the values were read from the saved rev 3.0 (2020-10-15) copy.