[Makers] remote SPI

Alastair D'Silva alastair at newmillennium.net.au
Sun Sep 19 12:21:37 EST 2010


> -----Original Message-----
> From: makers-bounces at makehackvoid.com [mailto:makers-
> bounces at makehackvoid.com] On Behalf Of Simon Burton
> Sent: Sunday, 19 September 2010 11:24 AM
> To: makers at makehackvoid.com
> Subject: [Makers] remote SPI
> 
> 
> Hi Makers,
> 
> I just thought I would follow up on my issues with getting this
> SPI interface to work over a distance. Thanks to everyone for
> helping out with this.
> 
> The 120cm cable definitely bites the dust. Even without an
> accelerometer
> board on the other end of the cable, it is enough to corrupt the SPI
> bus
> and kill comms to a local board (just next to the teensy micro).
> 
> I followed the suggestions on the sparkfun website and made some
> progress.
> 
> The best I have done so far is to get a 35 cm line to work. It required
> several tricks.
> (1) a 33 ohm resister on the (acc board's) SDI line (next to the
> teensy)
> (2) a 33 ohm resister on the acc board's power supply (also next to the
> teensy)
> (3) mount the acc board on another smaller breadboard
> 
> Without (2) or (3) it fails to work. Without (1) it is
> a noisy/unreliable line.
> 
> See photo here: http://arrowtheory.com/images/micro.jpg
> 

It may be worth trying twisted pair or shielded cables to improve the noise
rejection.

-- 
Alastair D'Silva           mob: 0423 762 819
Networking Consultant
New Millennium Networking  web: http://www.newmillennium.net.au
twitter: evildeece   msn: alastair at d-silva.org
blog: http://alastair.d-silva.org





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