USB peripherals
Contents
The Lending Library
The OLPC only has 512 megabytes of storage for Ebooks and other content. But CD-ROMs are cheap and could be used to distribute entire libraries. All you need to run a lending library is a stack of CD-ROMs and one or more USB CD-Readers.
CD-ROM
Probably one of the first extension or add-on that people think about for the laptop is the CD-ROM.
As any USB compliant device supported by Linux, they should work just fine. In that sense (USB 2.0 standard compliance) also means that any CD-R/W, DVD-R/W (and other letter combinations) should also work.
USB CD-ROMs are not as cheap as one may expect—when compared to internal CD-RW IDE starting around USD 20~30—an (external) USB CD-ROM or CD-RW starts around USD 70~90 and climb fast. Probably because they target the until-the-arrival-of-the-OLPC-exclusive-and-high-margin laptop market. Bulk prices (at OLPC scales) should make a noticeable dent on the price.
Mouse / Mice
Though external USB mice will work seamlessly with the laptops, their availability will be limited. See OLPC Human Interface Guidelines/The Sugar Interface/Input Systems to better understand why.
AD/DA & "Parallel" interfaces
Precisely for these types of ideas the computer needs some sort of basic A/D, D/A and suitably protected bi-directional "parallel" type interfaces. These need to be built-in so their use doessn't add wire spaghetti, cables/conversion boxes don't get lost, is "fumble free" and always available. In short, it must be simple, empowering and an idea generating catalyst. L Pfeffer March 20, 2006
- Or perhaps these miscellaneous fun things should all be available on a USB interface. It would keep it very expandaple, yet low base cost. USB devices keep getting less expensive to develop. --imajeff
Serial Port??
I know it can be done thru USB emulators... but serial ports are simple and easy to use. If someone wants to make some electronic project, or using old hardware (mouse, or serial comunications devices), it could be useful to have one.
it's just an idea, but I started making my first hardware projects with this, and even today is cheaper (at least here in Argentina) and easy to make serial ports working hardware (rather than buying PICs and programming them).
And still many hardware has serial ports (networking devices for example).
- Serial ports are NOT robust, at least nine tiny little pins that it's very easy to bend or break, not a good idea. Perhaps with a more robust connector, though IME the parallel port was more useful for electronics projects. 62.252.0.11 16:02, 17 March 2006 (EST)
- The photos from the developer boards show an external RS232 level shifter circuit attached (to some GPIO pins?). Legacy serial/parallel ports are nice for experimenting, there's IMHO no need for this for a laptop which is targeted at 6-12yo childs.
- Not to mention the fact that there IS NO OLD HARDWARE in these 3rd world villages. It would be far better to have an external power plug with circuit breaker switch so that people could use the old bananas they have laying around TO MAKE BATTERIES!!! The kids will be motivated to find a way to pedal less so lets help them learn some science.
More RAM
Its Flash memory can be expanded easily and cheaply by plugging in USB thumb drives for any user who needs one. Thus, if you have a chance to add a little more memory to the base unit, add a RAM chip, not a Flash chip!
I agree with this point... maybe the laptop should have a free slot to allow increase of ram ?? (at least is the possibility to add ram) that shouldn't be that much increase of costs...
- But if the case can be easily opened to insert RAM won't this make it easier for dirt and moisture to enter too? 62.252.0.11 16:14, 17 March 2006 (EST)
usb vs built-in flash
Question: What's the relative access speed of USB2 thumb drives versus the built-in flash memory?
The cheap solution to adding flash might be an under-lid USB2 port with a cut-out that lets you leave a flash device in-place when the laptop closes. This would not solve the RAM issue (as you don't want to swap to the flash), but it might be the lowest-cost way to give convenient storage expansion.
As the USB flash would be under the lid when the lid was closed, it would need to be in a recess to avoid hitting the screen or bevel. A 9x24x45 (DxWxL) mm recess will hold the popular smaller sticks while a 12x35x70 mm recess should hold even the largest USB sticks. Next to the touchpad, or along the top edge of the keyboard, or under the d-pad & speaker are all good locations.
USB Hard Drive
In the other hand, as John said, a USB thumb or hard drive, could be easily plugged. These devices currently start around 80 (USD) and 40 Gb. They are not 100% reliable when running of an underpowered USB port or an underpowered USB hub. Some manufactures slow down the drives to make them use less power. No budget USB2 drive could be considered a reliable, rugged, and robust companion to the OLPC PC.
One reason to consider the hard drive option would be to give the device an appropriate device to use for swap space. On the other hand, this may not be possible as the device would not be connected at boot/resume.
Note of course: A hard drive can easily be added by plugging one
into USB2 as well. One catch is that rugged, properly cooled
USB2 hard drives do not seem to exist at any reasonable price.
Another catch is power.
--John Gilmore
About the power of an external hard drive, I think if someone has money to buy it, it probably has electricity, so it's a matter of designing an external hard drive with with external power (or rechargeable batteries), if not, USB thumbs seems a good option, and they're getting cheaper.
- I understand there are 2.5inch hard disks that take a peak current of 600mA (at 5v) but thier average consumption is less than half that. I always though this would be a good spot for a rechargable battery. 62.252.0.11 16:14, 17 March 2006 (EST)
--Ecologists of Chios, Greece 21:24, 27 July 2006 (EDT)
I thought about an open design for a case for two hard disks, connected together, maybe even through software/hardware RAID, with a battery at the bootom of the case, as weel as a socket for a charger. So, you have twin 500GB hard disks connected in RAID to provide 1TB of storage through USB to the laptop, more than enough space for an entire wikipedia. The battery powers the disks, then when charging is needed it connects to the same charger as the laptop (simultaneously?). And of course design is rugged DIY with easily unscrewed access to the drives.
Keyboard Illumination
It is not necessary to illuminate the keyboard if fire is available in the target area. However, if the kids are willing to do the extra pedalling to provide light, there are nice cheap USB-powered LED lights available. This makes a lot more economic sense than burdening every device with illumination by building it into the keyboard.
GPS
- Main article: GPS
A GPS unit could be connected either through an RS-232-to-USB or Bluetooth-to-USB adaptor and be used in many contexts. One more reason why USB ports are a VERY good reason.
Networking
USB2
The USB2 interface hardware allows one of the USB ports to be used as a device port as well as a host port. This means that with the proper cable and software, two laptops could be plugged together and you could network them via USB2. They can be daisy-chained in the same way, and should provide ~20 Mbytes/sec of thruput (see GNU Radio USRP software for Linux software that can keep the USB2 bus moving data at maximum speed). There's USB device software in the Sharp Zaurus, which runs Linux and has such a dual-use USB port (USB 1.1 though).
A USB2 cable is much faster than the wireless, and cheaper than adding USB2 ethernet cards + hubs + cables + etc. Running IP, DHCP, and Rendezvous over USB shouldn't be hard; I'm a little surprised it isn't standardized already (like IP over Firewire).
--John Gilmore
- This is usb-on-the-go and needs the 5-pin tiny connector not the 4-pin normal sized ones because according to the designers it's only useful for PDAs and cameras not real PCs. Scheesh! 62.252.0.11 17:20, 17 March 2006 (EST)
- Also USB has alot of overhad associated with which slows it down and you need the a cable, which is limited to 5m (absolute maximum see if you can find one that longer much less someone in Africa). The wireless appears to have very high range and as it is a/g wireless they should be able to combine the two frequencies for 100Mbit/s which is only 4x slower than usb so not a big deal. Even if you don't use both a and g together and only get 50Mbit/s you can transfer 512Mbytes all the memory on the computer in 73 seconds. Thats plenty fast Lotu
Special Educational devices
It might be worthwhile to develop educational USB devices. One possibility would be a simple A/D converter with some sensors (temp, light, humidity, acceleration, etc). and input conditioning circuits. This would convert the laptop into a measurement device. With some software, it could be used as the basis for numerous science labs. It could also aid in repairing other laptops. Of course, such a device could be used with any USB-equipped computer.
See also OLPC as Datalogger.
Start collecting USB memory sticks
Smaller USB memory sticks are becoming obsolete as flash memory prices drop. It might make sense to start collecting them for eventual distribution with the laptops. They don't take up much space.
