some first impressions

Mitch Bradley wmb at
Sat Aug 11 04:28:38 EDT 2007

Hal Murray wrote:
>>  - some parallel port (or similar) should be made available, for
>> children to play with in physics. I remember playing with a PC
>> parallel port with some simple software to turn leds on and off. When
>> you are a kid, being able to send commands to projects you create is
>> great (think about modern legos, but using simpler stuff like leds,
>> motors, etc) : it translate the "virtual part" ie the software you
>> create on the computer to the "real world" where you make leds blinks
>> in sequence, or a motor move.
> ...
> There are USB connectors.
> ...
> USB to printer port adapters are also available.  I've never played with one. 
>  Prices are under $40.
> There are also things like this with 24 GPIO lines.
>   USBIO24R
>   US distributor:  $75
> ...  
> There is also the microphone input and audio output for A/D and D/A.  I think 
> the XO hardware supports a DC coupled mode.
> We should work on a collection of hacks to demonstrate how they work and a 
> list of which ones are known to work.

OLCP just had a summer intern, Arjun Sarwal, who developed some low-cost 
gadgets to plug into the mic port - temperature sensor, intrusion 
detector, etc.  He plans to document them and set up a framework for 
documenting other similar hacks.

We also talked about an OLPC digital gadget prototyping dongle with a 
USB-equipped microcontroller like those available from, for example, 
Atmel.  Those chips cost a dollar or two and Arjun can get all the other 
parts really inexpensively in India where he lives.

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