Kindle Scribe - USB-C "otg" setup?

[GeorgeYellow]

There seems to be 'reasons' to believe that USB-C based Kindle devices would support USB-C devices - in particular USB-Modems or USB-Audio.

However, every USB-C Hub seems to draw too much power , resulting in an oddly named "Moisture Warning".

Does anyone have recommendations for working hardware to use to enable USB-C as a Host?

[tomsem]

I think I tried one of my USB-C-to-audio adapters and found it didn't work. I am not sure I tried my fancier hub with pass through power, but doubt it would work either. The necessary system modules for audio out or other device support (e.g. keyboard) do not seem to exist on Scribe. Surely they'd have it in specs if there was such support.

[tekkasit]

Based on Amazon's past behavior with Bluetooth (clicker/keyboard) and micro USB (audio, external storage), it is very unlikely that they will add these features.

Enabling these features would require Amazon to implement software drivers and make code changes to the device. It is not as simple as just plugging in a device and having it work automatically.

[GeorgeYellow]

It appears that at least for the Kindle Scribe, as of the latest firmware, that there is an USB-Audio driver ("kernel/sound/usb/snd-usb-audio.ko"), setup ("usb_audio_setup.conf"), and handling code in "usr/lib/deviced/audiousb.so.1"

This doesn't appear to be locked behind flag files like other functionality....

[tomsem]

Originally Posted by GeorgeYellow

It appears that at least for the Kindle Scribe, as of the latest firmware, that there is an USB-Audio driver ("kernel/sound/usb/snd-usb-audio.ko"), setup ("usb_audio_setup.conf"), and handling code in "usr/lib/deviced/audiousb.so.1"

This doesn't appear to be locked behind flag files like other functionality....

That is interesting.

I'll try my adapter and/or cable again when I have a chance. I would much prefer to use wired headset (like you can with Voyage and PW3) than bluetooth, to the extent that I would use VoiceView or listen to audiobooks (not a very large extent). "Bring back TTS!!" and I would use it more (apparently the Chinese Kindle experiment with it was a one off).

[Quoth]

The USB audio driver was added for the PW3 as it has no BT. Likely they never took it out. A €6 generic USB-A audio stick with a generic OTG micro-USB plug to USB-A socket (€4) works on PW3 if you download the speech pack softwares. I think two downloads. It doesn't have KK3 / DX(G) style TTS, but a kind of voice view where everything is synthesised voice, not just the book text. It's very awkward compared to simple TTS only as on the Kindles with a 3.5mm jack. Personal experience of all 3 and compared to Android apps.

Really and app and phone is far better for TTS or voice-view as the screen blanks and saves most of the power. Audio on any eink dramatically wastes charge run time as normally eink slightly sleeps till you turn a page.

[RuggedPineapple]

Originally Posted by tomsem

I think I tried one of my USB-C-to-audio adapters and found it didn't work. I am not sure I tried my fancier hub with pass through power, but doubt it would work either. The necessary system modules for audio out or other device support (e.g. keyboard) do not seem to exist on Scribe. Surely they'd have it in specs if there was such support.

Try the fancier one, actually. USB audio pass through is part of the base USB stack with 3/3.1, but that does some things you wouldn't expect, like divorcing itself from the DAC and amplifier on the host device for the one that's on whatever's plugged into it. The cheap smartphone dongles don't have that equipment and aren't implementing actual audio pass through, but rather just treating the port as an audio port no different from a headphone jack.

[Quoth]

Originally Posted by RuggedPineapple

The cheap smartphone dongles don't have that equipment and aren't implementing actual audio pass through, but rather just treating the port as an audio port no different from a headphone jack.

Only an analogue connection is a dedicated "audio port".

The only difference between most phone USB Audio adapters and a PC USB Audio adaptor is a built in micro-USB, mini-USB or USB-C for OTG mode.

Obviously if there is USB but no +5V, a separately powered hub or a Y-cable to a USB charger will make a generic USB-A audio adapter work.

The iPhone audio adapters are for the Apple interface. They are the only common phone audio adapters as many Android phones and tablets have a 3.5mm jack and any supporting OTG will work with any generic PC USB-A audio I/O with a dumb wires-only adapter.

[tomsem]

Originally Posted by Quoth

The USB audio driver was added for the PW3 as it has no BT. Likely they never took it out. A €6 generic USB-A audio stick with a generic OTG micro-USB plug to USB-A socket (€4) works on PW3 if you download the speech pack softwares. I think two downloads. It doesn't have KK3 / DX(G) style TTS, but a kind of voice view where everything is synthesised voice, not just the book text. It's very awkward compared to simple TTS only as on the Kindles with a 3.5mm jack. Personal experience of all 3 and compared to Android apps.

Really and app and phone is far better for TTS or voice-view as the screen blanks and saves most of the power. Audio on any eink dramatically wastes charge run time as normally eink slightly sleeps till you turn a page.

I'm not at all concerned about power drain. It's entirely manageable.

I'm familiar with how Voice View works (including the older Kindles via OTG) but it is too intrusive (unless of course you have visual challenges).

My PocketBook Era has great TTS (Ivona, which Amazon owns). I don't use it much but it works well. Its audiobook player works in background as well. These are features I wish Amazon would add to Kindles, even if they contribute to power consumption.

As it is, I have very little use for Kindle audio capabilities, and for bluetooth generally (e.g. no support for connecting keyboard or page turning device).

That said, I don't expect this to change.

[tomsem]

Not surprisingly, my USB-C to audio adapter does not work with Scribe: it still insists on turning on Bluetooth.

[Quoth]

Originally Posted by tomsem

Not surprisingly, my USB-C to audio adapter does not work with Scribe: it still insists on turning on Bluetooth.

I'd expect that.

[RuggedPineapple]

Originally Posted by Quoth

Only an analogue connection is a dedicated "audio port".

Thats exactly my point. USB audio has several modes. Audio Accessory Mode spits out an actual analog audio signal over the USB port. This is often what cheaper accessories use because the audio hardware in the device continues to do the heavy lifting of conversion. USB ADC Mode sends a digital audio signal out over the port and offloads a lot to the USB device.

[RuggedPineapple]

https://www.soundguys.com/usb-audio-explained-18563/

Decent write-up of some of the differences, and quoted below:

For Audio Accessory Mode:

"USB Type-C audio connections don’t actually have to be digital: you can actually get analog audio out too. The USB standard also supports “Audio Accessory Mode”, whereby the D+/D- pins switch roles to support analog audio signals."

And for ADC (Audio Device Class) mode:

"The USB Audio Class specification allows a USB device to identify itself as an audio peripheral. This specification also determines a USB device’s compatibility with a range of specific USB functions and communication types suitable for audio."

[Quoth]

Originally Posted by RuggedPineapple

Thats exactly my point. USB audio has several modes. Audio Accessory Mode spits out an actual analog audio signal over the USB port. This is often what cheaper accessories use because the audio hardware in the device continues to do the heavy lifting of conversion. USB ADC Mode sends a digital audio signal out over the port and offloads a lot to the USB device.

Some Micro and Mini USB devices had that too. It's not a real USB mode, it's simply switching pins from USB to Analogue.

Some Canon DSLRs do this with the Mini-USB switching it to Analogue composite Video and Analogue audio.

Real USB audio uses D- and D+ data and on a "gadget" needs an OTG mode.

They simply made a non-USB mode of the connector part of a spec. I have a mini-USB port Smart Watch that does it too for regular 32 Ohm earphones. It saves a 30c 3.5mm jack socket.

All my USB audio adaptors are real USB using +5V, D- D+ and 0V. They are all USB-A connector, so need a USB OTG adaptor (which is a dumb connector). I do have some peripherals with the OTG wiring built in that can plug direct into mini-USB or micro-USB.
If USB Audio was going to work at all on any device later than a PW3, I'd assume it would only be real USB Audio, like the PW3 has.

Audio Accessory mode is NOT a real USB Audio mode. It's simply switching the connection wires to what would have fed a jack socket.

[RuggedPineapple]

Originally Posted by Quoth

Audio Accessory mode is NOT a real USB Audio mode. It's simply switching the connection wires to what would have fed a jack socket.

What? First, it is absolutely a real USB mode, it's defined on page 353 of the USB-C spec. You can get it from here: https://www.usb.org/document-library...ion-release-22

And then second, that's been my entire point. The cheaper adaptors typically implement Audio Accessory Mode. Meaning it's being fed analog audio. The kindle doesn't really have hardware to do that. The more expensive adaptors typically implement the ADC Mode, and therefore it's within the realm of possibility that the lack of proper sound hardware might be sidestepped, and it would be worthwhile to try since he mentioned he had some.