Jacek Wojciechowski's Forum Nokia Blog

Feel the power of USB OTG on Nokia Internet Tablets (and other mobile platforms)

2009-09-16T20:24:21+03:00

In my last post I wrote about local connectivity - this time I'd like to continue the topic and look into USB OTG possibilities that IMHO are not well advertised to the users and developers. Generally, almost all smartphone manufacturers are on the same level taking into account hardware (e.g. the same ARM processors, memory chips and other I/O components) - the biggest difference lies in the software/OS/integrated services and look&feel of the device. Of course, the manufacturers have many opportunities to improve the hardware/software (do you remember my post "Japanese vs European smartphone features" or "How future displays for mobiles may look like?"?). IMHO, the next big thing after touch (WOW factor guaranteed!) may be USB host feature (also called USB OTG or USB On-The-Go).

No one should be surprised that we can connect different USB accessories to our PCs, but some may be amazed that the same idea works on several mobile devices. Let's start with Maemo platform. With the help of on-board USB OTG chip, F-F USB adaptor and "USB Control" application (like Kate's usb-otg-plugin) you can connect for example:

* normal PC keyboard

* USB mass storage device (e.g. your smartphone, pendrive, digital camera, various digital audio players & portable media players)

* USB toys (like little fan, LED light, etc.)

The limitation lies in A) power consumption (not enough current to supply any type of USB accessory, in this case USB HDDs, USB CD burners; according to FN, N810 can power an external accessory with a maximum of 100 mA; a standard PC USB host may output up to 500mA per USB port), B) software/drivers (like tv tuner, printer, scanner, mouse support; some USB Hubs are supported after recompilation of the kernel which is not a perfect solution for the end-user). I have no doubt that this technology will be improved in the future (don't forget that USB host was rather hidden feature of internet tablets at the beginning). I eager to know whether there're some improvements in this matter in Maemo 5 devices like N900, so don't hesitate to post comments to this blog as soon as you get one!

And other mobile platforms?
It's a pity that we still can't play that way with USB host mode on S60 smartphones (AFAIK, USB OTG extensions were intoduced in Symbian 9.3; OS provides the support within its framework, but the provision of USB Host stack and drivers is left to licensees and partners). I hope that the idea I presented more than two years ago will be introduced in S60 and it will move beyond current possibilities (USB peripheral classes supported on S60: Wireless Mobile Communications Device class for serial communication with PC - used by Nokia PC Suite, Mass Storage class, Still Image Capture Device class, PictBridge/Picture Transfer Protocol, Media Transfer Protocol). USB OTG is available on selected Series 40 devices (USB Host classes supported: Digital Audio Class, HID class + USB peripheral classes). Linux-based Android should get USB OTG too. I've got a feeling that USB host (implemented for a rich functionality) may become a distinguishing feature of internet tablets for some time, but if I am not wrong, we may see similar functionality on S60 too. Till then, power users can use such adapters to have access to mass storage devices through normal microSD slot.

This may sound crazy, but imagine that you get a monitor, mouse and keyboard, USB Hub, Nokia Internet Tablet, then hook up everything only via USB and you suddenly have a desktop-lite PC. And that is only the beginning...

Thoughts on local connectivity, Nokia Internet Tablets and S60

2009-08-24T12:20:29+03:00

Have you ever needed to copy some files between Nokia Internet Tablet and S60 smartphone but there was no wifi network signal nearby and you didn't want to search for a running PC? I have, so I decided to take a look at possible solutions that don't involve internet connection (we can't use ftp, e-mail, SMB, etc.) and can be applied to N810 and N95-8Gb. The simplest way would be to use a microSD memory card, but not in this case, so let's focus on local connectivity.

The test setup: N95-2 (a.k.a. N95-8GB) v15.0.015, N810 OS2008 v5.2008.43-7, test file size: 10.045.112 bytes

1. Bluetooth for the beginning
N810's file manager has a great feature - you can simply manage files and folders available in paired devices using Bluetooth technology and supporting file transfer as you normally do with local files (don't ask me, why it's not a 'standard feature' also on S60). This simplifies the task (I don't have to search for 'send via bluetooth' option). Transferring ~10MB test file took 1m42s (N810 -> N95-8Gb and almost the same in the other direction). As you may guess... the more you test, the more different results you get, so I present only the best times. Simplicity is a big advantage here, but I'd expect more from Bluetooth 2.0 + EDR.

2. Wifi in Ad-hoc mode
N810's file manager can also display the shared content of available UPnP media servers (such server is available out ouf the box on S60 smartphones; you may also install UPnP media server on Maemo device, e.g. BRisa). Setting up the wifi ad-hoc for the first time is a little bit tricky (you need to remember to set the same SSID, channel number and you may use only WEP in this mode), but it's easy (and it's done only once). Please note that such network will operate in 802.11b mode, and get up to 11Mb of total bandwidth (according to specs, this is a normal behaviour in ad-hoc networks). Of course, you may use other software to copy data over wifi. The drawbacks of described solution are as follows: you need to spend time to set everything up (but you do this only once); when you want to copy not multimedia file with UPnP server, you have to rename the file extension first (to simulate multimedia file). Transferring the test file took 22s (N95-8Gb with UPnP server -> N810 UPnP client). Turn Bluetooth off, to get best times!

3. USB host mode
This is a very funny and easy way. First of all, you have to have a F-F USB adaptor and install "USB Control" application on your tablet (like Kate's usb-otg-plugin). How does it work? The USB uses a host/peripheral architecture. N810 acts as the host - like PC (USB Master role), and S60 smartphone acts as the peripheral - FAT-formatted flash memory card (USB Slave role). Such "memory card" works smoothly in N810's file manager. Transferring the test file took 20s for the first time, but 4s (!?) for the second time (from N95-8Gb to N810's internal memory; 26s and 16s respectively when transferred in the other direction). If you're curious, you may try 'time cp fileX fileY' or 'time gnomevfs-copy fileX fileY' commands and get... far better 'visual' results (well, it's linux!), but I'll stop at 20s achieved by N810's file manager - the software used for all tests.

I ended up with the following results: 98.48kB/s for bluetooth, 456.5kB/s for wifi and 502.3kB/s for USB. The results may vary depending on test method, testing environment and firmware versions. Bluetooth is currently the slowest, but it will change in the future because of new bluetooth standards - Bluetooth 3.0 HS. Fingers crossed, we'll get it on Nokia platforms soon (theoretically, it's a matter of some business decisions and proper firmware update; practically, we'll have to wait for new hardware-based implementation of chips, like this one)...

Of course, there's still room for improvements e.g. in pairing stage - just imagine holding two devices in one hand and shaking them twice in the same direction (all this goods thanks to accelerometer) or just touching them each other (NFC) to be paired. I would expect to see wireless USB or technologies like TransferJet to complete local connectivitiy options in future devices. Some of mentioned technologies are implemented on a limited number of phone models, but... what is your choice for a new local connectivity highspeed standard?

Developing 3rd party accessories for Nokia devices...

2008-01-23T12:45:35+02:00

Lately, I've noticed (possibly new) interesting section on Forum Nokia pages that describes Wired Interfaces on Nokia mobile devices and dedicated forum. The page introduces the following interfaces:

USB (with USB On-The-Go description)
Nokia AV 2.5mm/3.5mm Connector (for audio and/or TV out)
Nokia Pop-Port
Nokia 2-mm Charging Interface.

I'm a software engineer, but I like to know how sth is done and how it works in reality. If you're an electronic engineer, you'll know how to use described pin layouts and functions to create something new. IMHO, it opens a way for 3rd party innovative mobile accessories that will work with Nokia devices (iPod alike, e.g. docking alarm clocks, speaker systems, universal docks with remote, and others with music control). Maybe Nokia should create a special brand for compatible accessories named 'NAccessory' or 'NSeries Compatible/Certified device' like we have 'Designed for S60 Devices' logo for S60 apps...

microUSB in mobiles for charging, data and other tasks

2007-08-20T13:45:39+03:00

Not so long ago, Chinese government made a statement (source: People's Daily Online) about single national standard on mobile phone chargers sold in the country. They wanted to avoid waste and to lower costs: "Under the new standard, all mobile phones, regardless of the brand, will be able to share one charger with a USB access, allowing users to charge handsets through laptops. (...) China has almost 450 million cell phone subscribers, with up to 100 million replacing their phones every year. The chargers are often disposed of with the phones.".

Although no deadline had been set to allow charger makers to adjust their production, they responded quickly - Nokia did it as well (it's worth to note that China is the first largest market for Nokia in terms of sales, India being the second).
At the time of writing, five S40 devices have microUSB port (models: 8600 luna, 6500 classic/slide, 7900 prism, 6555). Some of these devices use microUSB for all connection types (one port for charging, data connection and audio), some have 2.0mm charger connector, 2.5mm audio and microUSB for data. It seems that Pop Port is not needed anymore. One big question is when microUSB with charging capability will come to S60 - will it be S60 3rd FP2 or later? The answer will come soon. Till then owners of devices with 2.0mm connector can use a special charger via USB (Nokia USB Charger CA-100).

I also have an idea - it would be interesting to use (micro)USB port in smartphones like we use in PC's. Just imagine connecting 'normal' PC's keyboard, mouse or additional flash memory to your smartphone through USB (is it a matter of proper device driver written for Symbian?)... one step in this direction is audio (which works directly through microUSB + headset HS-82 or AD-55 adapter).

Use of GPS and power consumption

2007-05-18T16:27:09+03:00

When we want to use GPS in our mobile devices we have two choices: either to use device with GPS onboard (like N95, E90, 6110 navigator) or to use external bluetooth GPS device. Each choice has some pros and cons. In-built means only one (convergent) device in the pocket, but using more power and having lower sensivity circuit; external - means additional device with its own power supply (plus probably additional charger to take care of!), more sensitive GPS (in addition: accuracy may be increased thanks to WAAS/EGNOS to 1-3m as opposed to the normal 10-15m; there may be included a logger of visited positions), such device will use power for computations and data communication only (for example every 1sec + maintenance of connection).

I'm beginning to wonder which solution is better when we think about power consumption. The answer seems to be simple: mobile device + external GPS, but could you share your experience (maybe someone has made some real tests) on how longer will such configuration work (+30% more time?)