Em Sáb, 2010-07-17 às 20:35 +0200, kang escreveu:
> I hope this is ok to ask such questions here.
> I've a project of my own where I want to plug a camera and a wifi
> stick to a small onboard computer.
> Gumstix looks like a good choice.
> My knowledge:
> - Linux, C, some kernel and user-land programming
> - Very basic electronics, soldering etc
Seems fine to me.
> My requirements:
> - encode ~720p30fps audio&video (TI's H264 codec+AAC)
Sorry, IIRC TI's DSP codecs for H264 only support up to 480p.
> - capture video via the USB 2.0 host (via UVC supported webcam that
> fits the above resolution and fps requirements on Linux)
UVC is supported.
> - transmit via the wifi stick (not the integrated wifi of the Overo's
> as it's not as powerful), transforming of of the micro usb port to
> another USB 2.0 host
The mini USB port on the Overos is connected to a USB-serial adapter to
allow easy debugging. Overos have two USB ports, one USB On-The-Go(100
mA max) and a conventional host port(500 mA max). The OTG port is
available as a mini-AB plug and the host port as a mini-A plug on most
Gumstix expansion boards.
> - as lightweight as possible
No problem - my Overo + Palo43 + 4.3" LCD(I use the LG one sold by
Gumstix, but there's a way to use a 5" 800x480 Samsung display instead,
with minor modifications. The LG sold by Gumstix runs at 480x272) seems
to be pretty light.
> - battery power (lipo + switching psu @ 5V, unless the COM onboard
> switching PSU can work off 1S lipo [3.7 to 4.2V battery] )
They can run directly on LiPo batteries IIRC.
> - Possible future extensions of the project using I2C and PWM
There's no driver for PWM IIRC, you have to write to /dev/mem to use it.
I2C seems to be supported, though.
> My idea:
> - Overo Water COM
> My questions:
> - Do I _require_ an expansion board, e.g. a Summit board, or is it
> easy to solder proper 2x USB host ports, Power plugs ? (this is for
> the weight)
No, but the connectors on the Overo have very fine pitch, so I recommend
you to buy a board or custom make one. Gumstix sells the connectors for
the Overo and they have expansion board schematics available for free to
help on your design.
> - Same question to use the audio input / output and eventually I2C and
Audio input and output are supported(though I never tested the input),
I2C and PWM answered above.
> -Does anyone have experience with the h264 encoding capabilities with
> the OMAP 35x (i've read the webpage about the performance, it seems
> acceptable). I want acceptable 720p video streaming.
> -Will the board provide enough power for both USB devices? (camera
> +wifi stick)
I think the camera may run on the OTG port(maybe you'll have to change
something on the driver to make it use devices with more than 100 mA
declared current usage), but the wifi stick definitively needs the host
> Thank you!
You're welcome! :)
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