LIDAR Lite V3 to Pixhawk

sbofill · December 3, 2019, 11:31am

Hi Team. I am trying to link up a LIDAR Lite v3 with a Pixhawk 2.1, either thru I2C or PWM. - and the LIDAR is not communicating with the PIXHAWK.

At the moment I am going for PWM and I know thru a scope and readout that the LIDAR itself is on and working fine. I have everything set up per this document - http://ardupilot.org/copter/docs/common-rangefinder-lidarlite.html

Setting the following parameters:

[RNGFND1_TYPE] = 5 “PWM”
[RNGFND1_PIN] = 54 “AUX5” (if using 4.0.0 or higher any Auxiliary output may be used)
[RNGFND1_MAX_CM] = 3500
[RNGFND1_MIN_CM] = 20
[RNGFND1_SCALING] = 1
[RNGFND1_OFFSET] = 0
[BRD_PWM_COUNT] = 4

And I am getting no readouts in Mission Planner for the LIDAR. Is there anyone out there that has done this and can help? What am I doing wrong?

I have heard I need different drivers? Sorry I am new to this but happy to give any/all info that you may need to help solve this problem. Any help is much appreciated.

-Steve

james_pattison · December 4, 2019, 6:28am

Do you have the resistor fitted?

ppoirier · December 4, 2019, 10:15am

James , are you certain that Analog (pwm) mode has been implemented on chibios yet?
I can’t find it in release notes

github.com

ArduPilot/ardupilot/blob/Copter-4.0/ArduCopter/ReleaseNotes.txt

ArduPilot Copter Release Notes:
------------------------------------------------------------------
Copter 4.0.0-rc2 04-Nov-2019
Changes from 4.0.0-rc1
1) Failsafe changes:
   a) GCS failsafe triggers when telemetry connection is lost (previously only triggered when using joystick)
   b) FS_OPTION parameter allows continue-in-auto and continue-in-pilot-modes for RC/Radio and GCS failsafe
2) Dynamic Notch Filter supports filter range based on BLHeli ESC feedback
3) Improved protection against high roll/pitch gains affecting altitude control
4) Bug Fixes:
   a) Altitude control param conversion fix (PSC_ACCZ_FILT converted to PSC_ACCZ_FLTE)
   b) BLHeli fix to RPM calcs and telemetry (aka 0x8000 error)
   c) ChibiOS SPI timeout fix (non-critical)
   d) Fence upload is less strict about altitude types (fences don't have altitudes)
   e) Motor loss detection bug fix (would sometimes think the wrong motor had failed)
   f) Pre-arm message fix to reports AHRS/EKF issue (was blank)
   g) Sparky2 autopilot firmware available
   h) Startup message "AK09916: Unable to get bus semaphore" removed (was not an error)
   i) Yaw control fix for fast descent and after large attitude disturbances
------------------------------------------------------------------

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james_pattison · December 4, 2019, 11:13am

That’s a good question. I’d assumed so, as there’s no reason it shouldn’t be (ie https://github.com/ArduPilot/ardupilot/pull/11951 works just fine)

ppoirier · December 4, 2019, 11:17am

But I cant see it in releases, according to @rmackay9 it was scheduled for release 4…

sbofill · December 4, 2019, 11:27am

HI James - Thanks for your feedback. Yep I have that Resistor fitted. I tried both 1KOhm as well as 500Ohm

sbofill · December 4, 2019, 1:47pm

Thank You James for responding.

Yes, the 1K resistor is installed as per this link http://ardupilot.org/copter/docs/common-rangefinder-lidarlite.html PWM section. Also have a BEC installed with a 470uF cap on the power ground and +5 volts. And we have it connected to AUX5 as per the link above.

I have an oscilloscope probe connected between Power Ground and the Mode Control connection and we see plenty of pulses. The pulse widths change when you put your hand over the LIDAR and raise your hand. Based on this I would suspect the LIDAR is functioning. The pulses have been observed all the way to the AUX 5 pin.

It seems to me, for lack of better terms, that the pixhawk doesn’t know what to do with this signal - aka - unsupported firmware.
Steve

ppoirier · December 4, 2019, 4:30pm

OK double checked and it should be working with 4.0 if you follow the updated wiki

@sbofill what firmware release have you loaded ?

sbofill · December 4, 2019, 7:28pm

I’m on 1.3.69, Build 1.3.7271.14198

rmackay9 · December 5, 2019, 12:52am

@ppoirier, yes I think the PWM input works. I spent some time testing it and reworked the wiki page a bit. The RNGFNDx_TYPE should be set to “5”.

ppoirier · December 5, 2019, 3:56am

You need to update to 4 so you can use any pwm input, as written in the wiki

sbofill · December 5, 2019, 9:35pm

You mean update from Build 1.3.7271.14198 to Build 1.4?

sbofill · December 5, 2019, 9:37pm

And sorry I’m very new to this but I really appreciate all your help - where could I find version 4?

ppoirier · December 6, 2019, 1:41am

Thanks Matt for the follow-up

sbofill · December 6, 2019, 4:19pm

Thank you both!! I’ll give that a shot this weekend and let you know how it goes. Really appreciate this.

sbofill · December 10, 2019, 12:32am

@ppoirier @Matt_C Thanks for the help. Is this the “v4” firmware I should be loading?

? (From this link: https://firmware.ardupilot.org/Copter/stable/PX4/)

ppoirier · December 10, 2019, 2:47am

No need to load beta as latest stable should have the updated driver

sbofill · December 10, 2019, 9:54am

I have a PX4v2 btw. So by “Latest Stable” you mean this? (Screenshot below)

sbofill · December 10, 2019, 9:57am

@ppoirier @Matt_C Hey this is random but are either of you available for a 5-10 min screenshare? I’d be happy to pay for your time. You guys have been very helpful so far but I’m still confused on what “v4” is and also I’m thinking a quick 5-10 min screenshare with your guidance as I hit these roadblocks would be ideal. Just throwing it out there.

PrateekJain · October 21, 2021, 11:23am

Hi,
Were you able to connect v3 to Ardupilot through PWM?
I was facing a similar issue!