Hi All,
We are having trouble with a PD - Arduino - Sharp IR gp2d12 IR
range sensor.
everything works for a while, then the arduino just stops and sometimes
takes PD down with it. once we had a warning from the OS that there
was too much current
being sucked on the USB port.
we are using three such things, each uses typically 33 and up to 50
mA. This
should (according to the Arduino and USB specs) not be too much, but
perhaps
these are wrong.
Any other ideas? I have heard of people using smoothing capacitors on
the
sharp sensors.
Hmm, puzzled in Linz,
Tim
Tim Boykett wrote:
We are having trouble with a PD - Arduino - Sharp IR gp2d12 IR range sensor.
everything works for a while, then the arduino just stops and sometimes takes PD down with it. once we had a warning from the OS that there was too much current being sucked on the USB port.
we are using three such things, each uses typically 33 and up to 50 mA. This should (according to the Arduino and USB specs) not be too much, but perhaps these are wrong.
I have built a circuit with six of those sensors on an Arduino Diecimila, it worked fine with external power, but I didn't even try it with USB power because for me 50mA is too much. (At first it crashed sporadically because I was sending too much data through the serial port.) The actual USB port you are using may not be able to supply that much current even if the USB circuit is able to handle it. If it only happens occasionally it's probably because the sensors sometimes pull more than the average current, so a ~100uF capacitor on the power pins would help, but you should really use a separate power supply for the sensors, or just power the entire Arduino externally.
Martin
that seems to be the case!
thanks
tim
On 30 Oct 2008, at 17:41, Martin Peach wrote:
Tim Boykett wrote:
We are having trouble with a PD - Arduino - Sharp IR gp2d12 IR range sensor.
everything works for a while, then the arduino just stops and
sometimes takes PD down with it. once we had a warning from the OS that there was too much current being sucked on the USB port.we are using three such things, each uses typically 33 and up to 50 mA. This should (according to the Arduino and USB specs) not be too much, but perhaps these are wrong.
I have built a circuit with six of those sensors on an Arduino
Diecimila, it worked fine with external power, but I didn't even try it with USB
power because for me 50mA is too much. (At first it crashed sporadically
because I was sending too much data through the serial port.) The actual USB
port you are using may not be able to supply that much current even if the USB circuit is able to handle it. If it only happens occasionally it's
probably because the sensors sometimes pull more than the average current, so a ~100uF capacitor on the power pins would help, but you should really
use a separate power supply for the sensors, or just power the entire
Arduino externally.Martin
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Martin Peach -
Tim Boykett