Sansa clip+ USB controller

[Echo]

Hi all,
My sansa clip+ (Rockboxed obviously) has a broken headphone jack.
Since they are out of production, and clip jam/sport are not (and probably will not be) supported by Rockbox, I want to try to use USB headphones.
I know that I'll have to do some coding, but first I have to make sure the USB controller on the sansa clip+ supports OTG.
Does anyone know if it is or how can I test it?

[saratoga]

I think all USB cores made in the last decade support OTG.  The spec is 15 years old and its only slightly different than normal USB (I think the core just needs one extra pin).

Edit: Although I guess it might be pretty hacky to implement if the sense pin isn't actually wired to the connector.

[wodz]

I know that I'll have to do some coding

Implementing usb host side of OTG would be HUGE coding effort really.

[Echo]

I know that I'll have to do some coding

Implementing USB host side of OTG would be HUGE coding effort really.

Well, that would depend on the controller interface. If I'm lucky, the send/recv interfaces are the same. If not - I'll probably have to find another way

Edit: Although I guess it might be pretty hacky to implement if the sense pin isn't actually wired to the connector.

Any idea how to check it without opening the casing of the device? After all, if I open the device, I might as well replace the headphone jack.
If it's not connected I have no idea how to implement this.

Thank you very much

[gomezz]

Does not the presence of Car Adaptor mode in Settings for the Clip+ indicate that this *is* supported?

[gevaerts]

Does not the presence of Car Adaptor mode in Settings for the Clip+ indicate that this *is* supported?

No, not any more than that the presence of EQ settings indicate that the rockblox plugin will work.

[saratoga]

I know that I'll have to do some coding

Implementing USB host side of OTG would be HUGE coding effort really.

Well, that would depend on the controller interface. If I'm lucky, the send/recv interfaces are the same. If not - I'll probably have to find another way

You'll still have to implement the host mode USB stack right?  The actual driver level bits are probably pretty small compared to that.

Edit: Although I guess it might be pretty hacky to implement if the sense pin isn't actually wired to the connector.

Any idea how to check it without opening the casing of the device? After all, if I open the device, I might as well replace the headphone jack.
If it's not connected I have no idea how to implement this.

I'd get a USBOTG cable and see if you can get the hardware to detect it.

Does not the presence of Car Adaptor mode in Settings for the Clip+ indicate that this *is* supported?

The car adaptor mode just checks to see if the device is externally powered.  It will work with a simple AC adapter, no USB required. 

[Echo]

The quoting got messed up so no more of this.

As to coding effort - The USB protocol itself (token / data / handshake) is implemented by the controller.
My job would be to implement the class driver, using the controller interface, that is - setting up endpoints and sending data to them.
I hope that sending data to an endpoint is the same in both host and device mods of the controller, if so - I can use the code written for device mod.

I hope I'm not too naive, but I'm still in the POC stage - and my first order of business is to see the HW is capable of this adventure.

As for you OTG cable suggestion - How can I know if the HW detected the device? I don't have JTAG or any other HW debugging tools
I tried to connect a disc-on-key using Rockbox and original FW, nothing happened

[saratoga]

As for you OTG cable suggestion - How can I know if the HW detected the device? I don't have JTAG or any other HW debugging tools
I tried to connect a disc-on-key using Rockbox and original FW, nothing happened

I mean, you write the driver to make this work, and then see what happens.  If you can't detect an OTG cable, there is probably no pin connected, although that can probably be worked around.