# HG changeset patch
# User Michael Spacefalcon <falcon@ivan.Harhan.ORG>
# Date 1420950828 0
# Node ID ed7318a03e0c17012e87ab2a33fd178677d2db0a
# Parent  805e99848aea77a9b7ec6180febdbe7a92294c9a
pirelli/vctcxo: VCTCXO connections traced out

diff -r 805e99848aea -r ed7318a03e0c pirelli/vctcxo
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pirelli/vctcxo	Sun Jan 11 04:33:48 2015 +0000
@@ -0,0 +1,32 @@
+Let's trace the TCXOEN signal from the Calypso.  Calypso ball A12, no trace
+visible, guessing a micro-via right under the ball.  L1 coord (3739,1053).
+Guess appears right: on L2 there is a connection from a micro-via to an inner
+via, the latter is at (3712,1055).  Found it on L4: the via is in the middle of
+a trace going both ways!  Right branch goes to (4548,1028); left branch goes to
+(1699,1349).
+
+Following the branch at (4548,1028): found it on L2, microvia back to L1 at
+(4518,1048).  Found it on L1, goes to some 2-pad footprint, can't tell if it's
+unpopulated or a faint black resistor.  The other end goes to a via at
+(4676,919).  Found it on L2, goes to inner via at (5135,684).  Found it on L7,
+goes to surface via at (5132,716).  Found it on L8 - goes to flash RY/BY# ball
+- WTF?
+
+Following the branch at (1699,1349): found it on L2, immediately goes back to
+L1 at (1673,1353).  Found it on L1, go to UL pad of the VCTCXO, passing by a
+cap to GND.  The cap is populated.
+
+Let's trace the signal from the VCTCXO to the Rita.  VCTCXO pin is unknown, but
+the input to Rita corresponds to a surface via at (2161,488) - at this point on
+L1 there is an unpopulated cap(?) to GND and a series component (cap?) to the
+actual Rita input.  Found it on L2, goes back to L1 at (2123,1284).  On L1 it
+falls right into the UR pad of the VCTCXO!  Conclusion: the signal from VCTCXO
+to Rita passes through a single series component, just like in Rita datasheet.
+
+The LR pad of the VCTCXO is GND.  Thus the control input must be the LL pad.
+The input signal to here passes first through a series component, then passes
+by a comp to ground, and then goes into the VCTCXO input.  The entry point to
+the whole arrangement is a surface via at (1669,1488).  Found it on L2, inner
+via at (1655,1467).  Found it on L4, goes to (2932,855).  Found it on L2,
+surface via to L1 at (2950,837).  That's Iota ball J4 (AFC), and there is also
+a branch from there that goes to an unpopulated cap(?) footprint to GND.