Delta2 LiDAR Driver [WIP]

This is a driver for the 'Delta2' lidar, available through various retailers on AliExpress.

Disclaimer: I am a Rust noob. Code quality is not a priority here.

This driver is a WORK IN PROGRESS, pending the following TODOs:

! Re-structure the code as a library, exposing the Lidar+MeasurementFrame structs
! Add Python support, using PyO3
! Test python build on Raspberry Pi
! Publish python builds to PyPy
! Handle the low-RPM health messages, serial disconnection, etc, with cleaner crate-specific exceptions
? Expose additional diagnostics such as scan rate, SNR, CRC error rates
? Handle serial re-connection ?

Install + Use (Python)

pip install git+https://github.com/leighleighleigh/delta2_lidar_rs

$ cat ./examples/stream-rerun.py

#!/usr/bin/env python3
from time import sleep
import numpy as np
from typing import List, Tuple

import rerun as rr # pip install rerun-sdk

from delta2_lidar import Lidar, MeasurementFrame, FullScan


# start rerun session
rr.init("delta2_lidar_rerun", spawn = True)

# connect to the lidar
dev = Lidar()
dev.open("/dev/ttyUSB0")


def to_3D(points: List[Tuple[float,float]]) -> np.ndarray:
    zz = np.zeros((len(points), 1))
    return np.hstack([points, zz])


while dev.alive():
    # read a measurement frame
    try:
      scan : FullScan = dev.read_full_scan()
    except:
      print("LiDAR disconnected?")
      break

    # set the time of this data
    rr.set_time_nanos("scan", scan.timestamp)

    # convert the 2D points to 3D
    points_xyz = to_3D(scan.points)

    rr.log_points("scan", points_xyz)
    rr.log_scalar("scan/rpm", scan.rpm)

Building

There are a few ways to build this package.

# build the rust library
cargo build 

# build and install a python wheel
./build.sh

# build with cross build
cross build --target aarch64-unknown-linux-gnu

Note on Motor (M+/M-) Voltage

I was originally running both the LiDAR MCU and it's motor from 5V - but the USB port + cable impedance meant that it was only running at about ~4V.

After adding a large capacitor to the 5V supply, the motor started to spin too fast for it to report valid range data.

I recommend running the motor from a stable 3.3V source for now, although ideally ~4V would maximize scan rate.