Effect upload and play

[sonik-br]

Hi @Kimplul,
I'm writing a "driver" to support TM Wheel on a RP2040 MCU.
The documentation here helped me a lot! :)
Already got working: initialization, effect upload and effect play.
I'm trying to figure out if it's possible to upload and play a effect with a single command/transfer.
Do you know if it's possible?

[MmAaXx500]

Hello, I'm not Kimplul, but I can add someting to the topic.
When I was working on the effects a few years ago I observed this behaviour (along others), but that is remained as a possible research area for the future. I left everything that I know in #110, quoting from there

The effect can be started immediately by setting the MSB bit of the new * effect field of an init packet. ea instead of 6a in case of constant effect. Using that, at the end of the packet 2 new bytes are appearing in connection with the iteration count of the IDirectInputEffect::Start method.

[sonik-br]

Thanks!
Going to read a look and do some tests.

I was trying to "upload an play" a spring (conditional) effect, using e4 instead of 64, and it did not work. I had to also send a play command after.
Going to try with a constant effect!

[MmAaXx500]

I just realized that you never said which TM wheel you are testing. All my observations are based on a T300RS.

Also, don't forget the two additional bytes on the end.

[sonik-br]

I forgot to say. Yes, it's a T300RS.
Can you point me to the two additional bytes?
I'm using this struct
https://github.com/Kimplul/hid-tmff2/blob/master/src/tmt300rs/hid-tmt300rs.c#L823-L829

[MmAaXx500]

You need to append a new field to that struct, so it will look something like this.

	struct __packed t300rs_packet_constant {
		<same as before>
		uint16_t maybe_iter_cnt;
	} *packet_constant = (struct t300rs_packet_constant *)t300rs->send_buffer;

I don't have a capture at hand at the moment, and never really figured out what the extra bytes are doing, but some suggestions for possible values are 0x1, 0xffff, 0xfffe 0x7fff, 0x7ffe, 0xff7f, 0xfe7f, 0x0100, 0x0101, 0x7f7f, 0x7e7e, 0x0. And of course set ea instead of 6a in the header.

[sonik-br]

Yay! It works!
Tested with Constant, Periodic and Conditional (spring).
Looks like it need the first bit set.
0x1 and 0xFFFF works.
0x0 and 0x0100 does not work.

Thank you very much! :)

There's another thing I'm trying to figure out.
If I enable default spring and set a force to it, and also set a max rotation on the wheel, it's not possible to "feel" the hard lock when rotation reaches limit.
This only happens with the default spring. If I set a Conditional Spring effect, it works as expected.
Have you seen this behavior?

[MmAaXx500]

By "default spring" you mean the autocentering force? I never played with effects while autocentering was on, so I don't have any experience with that, but I feel it is quite possible to play such an effect that applies the same force to your hand as the lock point. I would expect that you can't feel the lock either if you play a constant effect with max force (without autocentering).

[sonik-br]

Yes, auto center.
Even with autocenter at max, if rotation limiter is enabled, its not possible to feet it.
Somehow it works on windows. (autocenter+limiter).
I need to investigate this. But for now, I'm happy to get the upload+play on a single command.