--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pirelli/keypad	Sun Dec 01 23:59:56 2013 +0000
@@ -0,0 +1,27 @@
+Seeking to understand the 16-pin interface between the main PCBA and the keypad.
+Both connectors (the one on the main PCBA and the one on the underside of the
+keypad) have silkscreen with pin numbers around them, but the numbers in these
+silkscreen labels don't match: per the main PCB silkscreen, pin 1 is toward the
+edge of the phone, whereas per the keypad underside silkscreen, pin 1 is toward
+the middle.
+
+Here I will use pin numbers per the main PCBA silkscreen.
+
+Geometric centre of the footprint is at (3923,456) in steve-m's L8 scan.
+
+Pin 8: connected to massive copper flood, almost certainly GND.
+
+Pin 9: connected to a copper fill that's islanded by some traces, so it may or
+may not connect the same massive fill (GND?) as pin 8.  In this island there is
+a largish solid-connect via at (3915,475) and two smaller ones at (3766,539)
+and (3911,507).  On L7 these vias connect to massive copper flood - definitely
+GND.
+
+The keymap given in OsmocomBB (confirmed to be correct) indicates that the main
+keypad ought to use KBC0 through KBC3 and all 5 KBR lines.  The 3 side buttons
+use KBC4 and KBR1 through KBR3.  Let's try tracing the KBC and KBR lines of
+interest from the Calypso.
+
+Tracing KBC0, Calypso ball N4: goes to via at (4122,380).  Found it on L2, goes
+to a larger via at (4130,444).  Found it on L7, trace disappears into the edge
+grind-down damage.