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prod/doc/: completed section on component orientation (with pictures)

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Werner Almesberger
2011-05-29 14:46:00 -03:00
parent 46b15effa9
commit a662410560
6 changed files with 92 additions and 3 deletions
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prod/doc/analysis.hmac
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@@ -24,7 +24,50 @@
<SECTION ref="orientation" title="Component orientation">
@@@
There are several components whose footprint has a 180&deg; or even 90&deg;
rotational symmetry, but the component's electrical function is not symmetric.
Therefore, if such a component is incorrectly rotated, it will appear to the
casual observer to be properly placed, but it will not work.
<P>
These components are:
<UL>
<LI>the transceiver chip,
<LI>the microcontroller (<B>atusb</B> only),
<LI>the balun, and
<LI>the LED (<B>atusb</B> only)
</UL>
<!-- ---------------------------------------------------------------------- -->
<SUBSECTION title="atben components">
<B>atben</B> only has the transceiver and the balun. The markings on
both face towards the crystal and the antenna:
<P>
<A href="atben-compor.jpg"><IMG src="atben-compor.png"></A>
<P>
The corner next to pin 1 of the transceiver is marked with small dot.
The picture above also shows the orientation of the text printed on
the package. The balun is marked with a square between pins 1 and 6.
<!-- ---------------------------------------------------------------------- -->
<SUBSECTION title="atusb components">
In <B>atusb</B>, the marking on the transceiver is on the corner between
the crystal and the antenna. The marking on the balun faces towards the
antenna. The microcontroller's "top" side faces towards the USB connector.
<P>
<A href="atusb-compor.jpg"><IMG src="atusb-compor.png"></A>
<P>
It is difficult to determine the LED's orientation by visual inspection.
An efficient approach is to touch the LED's terminals with the probes
of a multimeter set to measure resistance. The small current used for
the measurement will light the LED.
<!-- ====================================================================== -->