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zlite opened this issue Mar 1, 2021 · 26 comments
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Latest RPLidar firmware has broken this library #15

zlite opened this issue Mar 1, 2021 · 26 comments
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@makermelissa @caternuson

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@zlite
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zlite commented Mar 1, 2021

Starting in 2021, all RPLidar hardware is shipping with firmware 1.29, which breaks this library (error shown is "Incorrect descriptor starting bytes", but that just means that it got no data). Slamtec says that this may be due to the default scan mode being changed to boost mode. They say that they do not support Python(!) and are not intending to fix these libraries. They say it's up to us to fix them ourselves :-(

AFAIK there is no way to downgrade the firmware to a previous version (last known good was 1.27), so I think that until distributors can get Slamtec to help fix these libraries, we have to now consider the RPLidar devices unsupported in Python
@ladyada
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ladyada commented Mar 1, 2021

@zlite is there a document with the protocol output for 1.29

@zlite
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zlite commented Mar 1, 2021

Yes, it's here. I don't think that the protocol has changed, but rather the default mode has changed from standard to boost.

@ladyada
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ladyada commented Mar 1, 2021

doesn't look like there's that much different, wanna take a poke at adding a scan mode query check

@caternuson
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(error shown is "Incorrect descriptor starting bytes", but that just means that it got no data).

Is it that or because something changed in the return and this check now fails:

Adafruit_CircuitPython_RPLIDAR/adafruit_rplidar.py

Lines 224 to 225 in 9f4bb20

if not descriptor.startswith(SYNC_BYTE + SYNC_BYTE2):
raise RPLidarException("Incorrect descriptor starting bytes")

Try enabling logging which should print the actual descriptor value.

@zlite
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zlite commented Mar 5, 2021

Looks like another Python library solved it this way:
Roboticia/RPLidar@787ff8d

@makermelissa
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Hi, do you have any idea where to download firmware 1.29? It looks like the latest on their website is 1.27.0 (https://www.slamtec.com/en/Support#rplidar-a-series).

@zlite
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zlite commented Mar 5, 2021 via email

@makermelissa
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Do you have one of the ones with 1.29 you could test if I were to make changes? I can test that it still works on the old ones at least.

@zlite
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zlite commented Mar 6, 2021 via email

@makermelissa
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Ok, want to test out #16?

@zlite
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zlite commented Mar 9, 2021 via email

@makermelissa
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Ok, I'll probably need to get one with 1.29 firmware then as there's probably a bunch of differences.

@benlbroussard
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I've got 1.28, which works, but is getting 2k scans/second, when it could be getting 8k using boost.

I'm looking at the c++ sdk here: https://github.com/Slamtec/rplidar_sdk/blob/master/sdk/sdk/include/rplidar_cmd.h#L59

Also, the protocol document talks about boost mode (hq mode in the c++ code) but doesn't give the hex value (0x83).

I'd love to see boost mode implemented as the solution to this! Also, get lidar conf (0x84) could be used to ensure backward compatibility.

@makermelissa
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Thank you @benlbroussard,

The feedback was very helpful. It sounds like the changes I made were in the right direction and I just need to add boost mode handling. I'll give that a try and update my PR as soon as I finish up with another task.

@zlite
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zlite commented Mar 15, 2021

A little update. I can get the Robotica library to work with the 1.29 firmware, at least as far as the below example goes:

from rplidar import RPLidar
lidar = RPLidar('COM7')

info = lidar.get_info()
print(info)

health = lidar.get_health()
print(health)

for i, scan in enumerate(lidar.iter_scans()):
    print('%d: Got %d measures' % (i, len(scan)))
    if i > 10:
        break
lidar.stop()
lidar.stop_motor()
lidar.disconnect()

Output:

{'model': 24, 'firmware': (1, 29), 'hardware': 7, 'serialnumber': 'EBB399F6C9E59AD2C5E59CF717613412'}
('Good', 0)
0: Got 52 measures
1: Got 63 measures
2: Got 61 measures
3: Got 62 measures
4: Got 58 measures
5: Got 56 measures
6: Got 55 measures
7: Got 56 measures
8: Got 61 measures
9: Got 61 measures
10: Got 57 measures
11: Got 60 measures

But your library still generates a "Descriptor length mismatch"

@zlite
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zlite commented Mar 15, 2021

This also works with the Robotica library:

import sys
import numpy as np
from rplidar import RPLidar

def run():
    '''Main function'''
    lidar = RPLidar('COM7')
    data = []
    try:
        print('Recording measurments... Press Crl+C to stop.')
        for scan in lidar.iter_scans():
            data.append(np.array(scan))
            print(scan)
    except KeyboardInterrupt:
        print('Stopping.')
    lidar.stop()
    lidar.disconnect()


if __name__ == '__main__':
    run()

Output:

Recording measurments... Press Crl+C to stop.
[(15, 40.3125, 504.5), (15, 55.65625, 251.75), (15, 104.09375, 166.75), (15, 119.75, 157.5), (15, 120.328125, 298.5), (15, 122.28125, 294.0), (15, 201.578125, 780.0), (15, 202.859375, 778.0), (15, 204.21875, 779.75), (15, 205.453125, 782.5), (15, 206.765625, 786.5), (15, 208.015625, 790.75), (15, 209.390625, 794.25), (15, 210.703125, 797.5), (15, 211.921875, 802.75), (15, 213.15625, 809.75), (15, 224.28125, 1288.75), (15, 225.5625, 1308.75), (15, 226.796875, 1331.0), (15, 228.0625, 1352.75), (15, 229.359375, 1378.5), (15, 230.6875, 1411.5), (15, 231.921875, 1442.0), (15, 233.21875, 1472.25), (15, 245.25, 389.75), (15, 247.8125, 396.75), (15, 249.109375, 397.75), (15, 268.59375, 596.25), (15, 269.859375, 597.25), (15, 271.15625, 605.0), (15, 272.34375, 610.75), (15, 273.609375, 625.0), (15, 274.84375, 634.5), (15, 278.4375, 2014.5), (8, 282.40625, 1751.25), (14, 283.71875, 1760.25), (15, 285.046875, 1761.75), (15, 286.359375, 1766.75), (15, 287.640625, 1771.75), (15, 288.9375, 1779.25), (15, 290.21875, 1791.0), (8, 291.46875, 1799.75), (15, 295.3125, 1957.5), (15, 301.828125, 2036.25), (15, 322.3125, 297.5), (15, 348.109375, 246.0), (15, 349.46875, 246.25), (15, 349.75, 242.75), (15, 351.71875, 241.5), (15, 354.0, 242.5), (15, 353.5625, 243.75), (15, 357.171875, 244.75)]

@makermelissa
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Thanks, that's actually pretty helpful as I was referencing it for my update.

@makermelissa
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@zlite I updated the PR a bit. Want to try that out? I think that's about the best I can do without a 1.29 firmware model in hand to actually work with.

@zlite
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zlite commented Mar 17, 2021

Still getting "wrong body size" I'm afraid. Sorry! The RPLidars sold by Seeed on Amazon are using the new 1.29 firmware

Also the import in the repo's readme of from adafruit_circuitpython_rplidar import RPLidar doesn't work. You have to use from adafruit_rplidar import RPLidar instead

@makermelissa
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Oh, ok. Wrong body size is a different error, so that's progress.

@zlite
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zlite commented Mar 17, 2021

Actually, the first time you run it the error is "wrong body size". The second time it's "Incorrect descriptor starting bytes". Then back to "wrong body size" and so on forever

@satiowadahc
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Debugging and debugging and debugging... timeout=3... huh everything's working...

@zlite
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zlite commented Apr 29, 2021

As in "lidar = RPLidar(None, PORT_NAME, timeout=3)"?

Cool! I'll give it a try

@satiowadahc
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satiowadahc commented Apr 29, 2021 •
edited
Loading

Also Express needs a payload now
?? can be 0x00-0x04

        if scan_type == "express":
            print(cmd)
            self._send_payload_cmd(cmd, b"\x??\x00\x00\x00\x00")

@zlite
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zlite commented May 4, 2021

@satiowadahc It works! That's so crazy, but timeout=3 was the secret.

Will submit a PR with a corrected example. I've tested it with both old and new RPLidar firmware

@makermelissa This is good news. I think you've cracked it. Bravo

@makermelissa
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Fixed via #17

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@zlite @ladyada @makermelissa @satiowadahc @caternuson @benlbroussard