acceleration and deceleration

[valentinptc]

Hi, I would love to slowly accelerate and deceleration the motor to a precise angle. I get it to to accelerate, but I cant figure out how to slow down the motor at the end of the command. I can only call another degree command and the motor will transition from one to the other speed.

I can find the following in your documentation* but its unlcear what the meaning is:

0x0000000? | Acc.- profile 0x000000?0 | Decc.- profile

*3.27.9. Output Sub Command - StartSpeedForDegrees(Degrees, Speed, MaxPower, EndState, UseProfile) [0x0B]

Here is the command I send:

0x0D, 0x00, 0x81, port, 0x11, 0x0B, motorbytes[0],motorbytes[1],motorbytes[2],motorbytes[3], speed, 100, 127, 0x00000021]);

I was playing around with the last byte wondering if I can figure out what the meaning of the two question marks are.

[Vouzamo]

I believe the profile is a byte where bit flags are used for profiles.

As such, the following would apply:

• 0b00000000 No profile
• 0b00000001 Accelerate
• 0b00000010 Decelerate
• 0b00000011 Both

[Vouzamo]

Also, make sure you have configured the profiles for:

• Acceleration: https://lego.github.io/lego-ble-wireless-protocol-docs/index.html#output-sub-command-setacctime-time-profileno-0x05
• Deceleration: https://lego.github.io/lego-ble-wireless-protocol-docs/index.html#output-sub-command-setdectime-time-profileno-0x06

[valentinptc]

I have set both profiles separately and I also applied the flags to set the motor moving. One thing thats confusing with setting the profiles is ProfileNo [Int8]: [0..MAX_PROFILES]

If I change ProfileNo to anything else than 0x01 for acceleration, the motor behaves unexpected. The deceleration profile seems to have absolutely no impact. I tried changing all kinds of values for an hour or so. I think I tried all possible combinations. Something important is missing from the documentation or the boost firmware has a bug.

[valentinptc]

anymore hints? Acceleration is working, deceleration is not working. I there anyone else who got this working?

[Vouzamo]

Have you tried 0b00000010 for the Profile # when setting Deceleration?

I suspect the internal function being used is the same for both acceleration and deceleration. More of a generic, set time for profile where profile # is the flag of the profile to configure.

Best,

John

On Mon, Apr 27, 2020, 09:59 valentinptc [email protected] wrote:

anymore hints? Acceleration is working, deceleration is not working. I there anyone else who got this working?

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[valentinptc]

I did, yes. Actually I tried every possible combination. The documentation could win a lot if there could be one or two more paragraphs to explain the exact relationship between the bitmask and the profiles. At this point however I believe there is a bug in the firmware.

[Vouzamo]

When I have more time I will set up a motor on my C# SDK and experiment with the profiles myself. I suspect there is something missing from the docs but will let you know if I uncover anything.

On Mon, Apr 27, 2020, 10:10 valentinptc [email protected] wrote:

I did, yes. Actually I tried every possible combination. The documentation could win a lot if there could be one or two more paragraphs to explain the exact relationship between the bitmask and the profiles. At this point however I believe there is a bug in the firmware.

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[valentinptc]

Thank you! When do you expect to have more time?

[renegrob]

For me it worked: I called SetAccTime and SetDecTime for profile 0, note that the millis is a 16 bit value where the first byte is the low byte (little-endian), then I called StartSpeedForTime with profile = 3 (0b0011). I used accTime = 1000, decTime = 1000 and a time > 2000 for StartSpeedForTime. Trying to set the profile value for SetAccTime different than 0 caused the connection to abort.