Originally Posted by malfunctioning

USB keyboard is not an option, since the N900 would need to remain connected to the AC supply continuously.

Originally Posted by herpderp

Something like this?

I don't think the N900 can do that in an acceptable manner. Android is getting closer with each release. Maybe if Maemo was continued... But that's another story.

Originally Posted by Piotrek_PL

Why not use a usb hub with an external power supply? It would charge the battery and allow you to connect other devices.

Originally Posted by herpderp

Something like this?

I don't think the N900 can do that in an acceptable manner. Android is getting closer with each release. Maybe if Maemo was continued... But that's another story.

Originally Posted by Estel

Using kernel-power and Pali's BME replacement bits (or even without them, but then you need to execute some scripts manually), you can have USB 2.0 hub connected to N900, <whatever> number of devices connected to that HUB, and N900 charging from USB - all at the same time.

Originally Posted by Estel

Personally, I use USB keyboard *and* USB mouse, handled by extkbd and extmou packages, respectively (this way, you don't need to stick for some over-priced brands, you may use whatever you want, and generic ones are going to work perfectly). N900 is connected to flat TV's via video out.

Originally Posted by Estel

The last part is bootleneck - there isn't problem with 800x480 upscaling, that would be still ideal. The problem is, that video out does *downscaling* to PAL or NTSC, which is main reason for blurriness (be sure to use PAL when available, it have slightly better image quality, due to more lines).

Originally Posted by Estel

One of things that I finally need to set up "someday", is making a nice travel body for my Raspberry Pi, and, paired with N900 via USB networking, using it as HDMI video out for Easy Debian (at any resolution we feel fancy, even monitor/TV native ones). It all works perfectly well - there are just some glitches with USB keyboard, as extkbd *still* isn't working well with xephyr, so no good external keyboard mapping inside Easy Debian's LXDE (freemangordon, I'm looking at you). One could workaround it by installing bt-hid-scripts package everytime one want to have xephyr and external keyboard, then revert back to extkbd afterwards, but it is a PITA.

/Estel

Originally Posted by malfunctioning

Thank you for confirming that. Do you think it would be possible in the future to be able to use the N900 connected directly to AC without any battery? That's another of the things I hope are possible.

Originally Posted by malfunctioning

I might dedicate one of my N900s to be used like this. I like the fact that it wouldn't be necessary to connect / disconnect the N900 from USB often, as connections would take place on the other end of the hub if necessary. It plays well to one of the N900's weaknesses (the tendency for the USB connector to break).

Originally Posted by malfunctioning

Wait, but NTSC is 480 vertically, just like the native resolution of the N900, isn't it? I honestly don't get how upscaling to 576 (PAL) helps, but I do believe you. I just don't understand how that would help.

Originally Posted by malfunctioning

I didn't know it would be possible to achieve (kind of) arbitrary resolutions from Easy Debian through the Raspberry Pi. Do you use it often? Isn't there a bandwidth problem to achieve a reasonable frame rate at higher resolutions? Anyway, that is very impressive.

Originally Posted by Estel

Sadly, no AFAIK, it's hardware limitation, of how charging chip behaves. It *can* run N900 from AC without battery inserted in so-called emergency mode, and that was abused to Proof-of-concept hotswap of battery, but it require turning everything off and dimming screen. It just won't give enough juice to device itself, for any normal operation.

Originally Posted by Estel

A way to achieve this, would be:
a) build a dummy battery, which is just <any_material> brick and "battery" pins connected to ~4.1 power source (+ 100kOhm resistor between BMi PIN and ground - the easiest way, would be to just cut off a PCB from any real N900 battery, and [ab]use it). N900 would just think, that it's connected to battery, that never runs out

Originally Posted by Estel

I'm perfectly sure, that it's the way N900 were powered at Nokia labs - BMI sense probe have even a certain identification range, that tells device it's running from dummy (just a curiosity, not important for us in any case).

Only drawback for this scenario, is that you may find hard to find uncommon ~4.1 power source. Dirty hack to achieve it, would be to connect normal 5V charger through a series of diodes, until it drop to ~4V (or even less, for safety margin), but you would want to test thoroughly how redundant voltage drop is (depending on temperature, moisture, etc) - unless you consider smell of fried chips at the morning a beautiful thing In such case, I would even go for 3.7V target voltage, for safety margin (I don't think that voltage would ever1 change from 3.7 to above 4.2 or under 3.3, even at wide amplitude temperature changes).

Originally Posted by Estel

Be sure, to check thread about reinforcing USB port. It's quite easy process (if basic caution rules obeyed), and almost ensures no USB port-related problems.

Originally Posted by Estel

But horizontal resolution is 720, so if you're using widescreen output (most likely case, as you probably doesn't want to have distorted proportions of programs displayed from N900 - still, N900 TV-out also allows 4:3 output), it goes some mumbo-jumbo with conversion, and practical result is, that you just want higher resolution output possible Also, "resolution" in terms of video out is just a simplification - in fact, it does interlaced lines, so it work a little differently than one would expect. I must admit, that N900 does awesomely good work at conversion, and result is much higher quality, than most devices with video-out offers. Still, it's nothing, compared to having HDMI output

I've done tests- using flat TV, that accept both PAL and NTSC input - and PAL from N900 looked slightly better in all cases. Of course, I can't guarantee it to be the same on other monitors/TVs, so you're encouraged to do own tests. Also, I must admit, that difference is hardly noticeable (you need to look for it, preferably through using reference/calibration images, to see it).

Originally Posted by Estel

See this thread:
http://talk.maemo.org/showthread.php?t=81408

(solution for Easy Debian is somewhere in middle-to-end posts, but I think it's worth to read whole thing, to get better picture). Sadly, I'm not using it often, due to mentioned problems with extkbd in LXDE (Xephyr) *bugs freemangordon again*. But, it is indeed impressive, and 25/35$ (depending on version) for a RPi for that purpose isn't too much (not to mention, that RPi can do many other things, too).

As for bandwidth - you're using USB Networking, so N900 can be in both client *or* hostmode. If you're using Pi as host and N900 as client, there are 0 problems, no matter of resolution output (up to FullHD 1080p). If you're using N900 as host, thing *may* look differently - our hostmode isn't ideal implementation, as practical transfer limits are around 4 MB/s (that is, *lower* than WiFi!). Still, in practice, I haven't seen any problems - using different X video output is very efficient. Keep in mind, hoever, that I haven't tested it so much as N900-as-client scenario.

Originally Posted by Estel

Now, if you're using N900 as client you can't, obviously, connect client devices (keyboard, mouse...) to it - it can't be client and host at the same time. But, you can connect those to Rpi, and stream input to N900'sMaemo Crazy, but works. If one would took effort to compile some FOSS USB-over-Network tools for N900, it would be, probably, possible to stream, *any* USB device connected to Pi back into N900, eliminating need for (physical) hostmode on N900 itself, as those tools create a "virtual" USB root hub. You would still need modules on N900's kernel side, though (just like now). OTOH, HID devices (keyboard, mouse, again...) doesn't need streaming USB protocol itself, you may just forward input devices at higher level.

Generally, possibilities are endless

/Estel

//Edit:
Added more info about RPi scenario.

Originally Posted by malfunctioning

Now, I can imagine that the electrical circuit from the USB port to the battery is not the same as the circuit from the USB port to the mainboard, so maybe this theory is incorrect.

Originally Posted by malfunctioning

And, if they have truly crippled this possibility in the hardware (as you say, and I trust you), then this conversation is moot. One thing I like about my Zaurus SL-C1000 (I don't know if you are familiar with it, just a Linux PDA from a few years ago produced by Sharp in Japan) is that it can be operated without battery (although if you try to use the CF card port under those conditions, it will shut down).

Originally Posted by malfunctioning

Yes, that's a great idea! And I'm sure it's doable. It would be nice to get somebody in China interested in the business of virtual batteries. I hate for devices to became obsolete when their perishable power sources die and become unavailable.

As for the difficulties in getting something like this to work, it's one of those things that you wish some manufacturer actually got interested in, as I said earlier. Put some R&D into it, come up with a solid reliable product, mass produce it, and profit. Win/win situation.

Originally Posted by malfunctioning

I had seen that in your signature, but I haven't taken the time to go through that thread yet. I'll make sure to do that soon. Getting 1080p with the N900 as client is crazy, certainly not something I would expect

Originally Posted by malfunctioning

I had to read that twice. So you are saying that the N900, connected as a client to the Pi, can access other devices connected to the Pi via USB? Or, I guess, you put it more like "the Pi can route the input back to the N900", which I guess is a little less shocking, but still!

Originally Posted by malfunctioning

Can't say I've found many people that have hacked, abused, and stretched the capabilities of the N900 like you have. You are a madman, Estel.

Thank you for the extensive thread full of great information, by the way. It is very appreciated.