doppler/HLK_LD2451_monitor.py at master · jbeale1/doppler · GitHub

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# monitor serial packets from HLK-LD2451 24GHz FMCW speed sensor
# based on HLK LD2451 serial protocol manual pdf
# Version:  V1.03  Modification  date:  2024-7-1
# JPB 4/16/2025

import serial
import time
import datetime
import os

# port = "/dev/ttyUSB0"  # port connected to HLK-LD2451 sensor
port = "COM11"
logdir = r"C:\Users\beale\Documents\radar"

def sendCmd(ser, enacfg):
    ser.write(enacfg)
    time.sleep(0.2)
    if ser.in_waiting > 0:
        data = ser.read(ser.in_waiting)
        print(data.hex())


timestamp = datetime.datetime.now().strftime("%Y%m%d_%H%M%S")
filename = f"LD2451_log_{timestamp}.csv"
logfile = os.path.join(logdir, filename)

ser = serial.Serial(port, 115200, timeout=1) # connect to the serial device
print("Serial port %s opened." % port)

header = b'\xf4\xf3\xf2\xf1'  # normal status packet start/end
trailer = b'\xf8\xf7\xf6\xf5'

cheader = b'\xfd\xfc\xfb\xfa' # control packet start/end
ctrailer = b'\x04\x03\x02\x01'

cstart = b'\x04\x00\xff\x00\x01\x00'  # enter config mode
cend = b'\x02\x00\xfe\x00'            # leave config mode
cset1 = b'\x05\x00\x02\x00\x64\x01\x05\x02' # max 0x64 m, toward only, min 0x05 km/h 2s delay
cset2 = b'\x05\x00\x02\x00\xc0\x02\x02\x02' # max 192 m, either dir, min 4 km/h 1s delay
csense = b'\x06\x00\x03\x00\x01\x04\x00\x00' # 1 trigger count, 02 SNR thresh

noTarget = b'\x00\x00'               # no-target-present data
enacfg = cheader + cstart + ctrailer # assemble command packet
discfg = cheader + cend + ctrailer
doset2 = cheader + cset2 + ctrailer
dosense = cheader + csense + ctrailer

if ser.in_waiting > 0:
    data = ser.read(ser.in_waiting)

print("Sending config mode cmd")
sendCmd(ser, enacfg) # enter config mode
sendCmd(ser, doset2)      # set configuration
sendCmd(ser, dosense)      # set trigger, sensitivity
sendCmd(ser, discfg)      # exit config mode
print("Entering monitor mode")

try:
    with open(logfile, "w") as fout:
        fout.write("epoch,len,x,num,alm,deg,m,dir,kmh,SNR\n")

        quiet = True  # no signal detected
        while True:
            if ser.in_waiting > 0:
                data = ser.read(ser.in_waiting)
                bytes = len(data)
                if (data[0:4] == header) and (data.endswith(trailer)) and (bytes > 8):
                    payload = data[4:-4]
                    if (payload == noTarget):
                        print('.',end="")
                        quiet=True
                    else:
                        if quiet:
                            print()
                            quiet = False
                        tnow = time.time()
                        payload = data[4:-4]
                        # hex_string = ' '.join([f'{byte:02x}' for byte in payload])
                        values = ', '.join([f'{byte:03d}' for byte in payload])
                        buf = ("%.3f, %s\n" % (tnow, values))
                        print(buf,end="")
                        fout.write(buf)

except KeyboardInterrupt:
    ser.close()
    print("Serial port closed")

"""
epoch_time      pktlen     #   Alm  deg   m   dir km/h  SNR
1744901290.522, 007, 000, 001, 000, 128, 014, 000, 004, 255
1744901290.542, 007, 000, 001, 000, 121, 014, 000, 004, 255
1744901291.179, 007, 000, 001, 001, 128, 013, 001, 003, 123
1744901291.205, 007, 000, 001, 001, 123, 013, 001, 003, 123
"""