--- a/pirelli/audio	Fri Aug 02 02:16:31 2013 +0000
+++ b/pirelli/audio	Sun Oct 20 04:49:28 2013 +0000
@@ -17,3 +17,24 @@
 Found them on L7: fat traces to micro-vias at (3870,934) and (3898,869).
 Finally on L8 they go to the Winbond chip!  The speaker connection pins appear
 to be the two leftmost ones in the top row of 9 pins.
+
+Calypso-Iota Voice Band interface
+
+Tracing the Calypso voice output signal, starting from Calypso ball P14 (VDX).
+On L1 it goes to a via at (3401,429).  On L2 it branches: one end goes to
+(3366,304) - suspected via back to L1 for a test point, and the other end goes
+to (2885,917) - also a suspected via back to L1.  Found the 1st branch on L1:
+it's a short trace to another via at (3291,304).  Found the 2nd branch on L1
+too: it goes to Iota ball F5 (VDR), matching the Leonardo schematics.
+
+Now let's trace the branch that went to (3291,304) on L1.  On L2 it goes to a
+short trace that goes to (3349,197) - suspected micro-via back to L1.  Looking
+on L1: yes, indeed the trace seems to lead back here, but then the edge
+grind-down damage gets in the way.  Looking at the L1 populated photo, the
+trace definitely seems to go to an exposed test point.
+
+The apparent lack of a switch or MUX on the Iota digital voice input strongly
+suggests that in Wi-Fi VoIP operation the Calypso DSP acts as a forwarder for
+the digital voice samples, which are being fed to it from the VoIP chip via
+another interface: MCSI, or perhaps the otherwise unused MODEM UART switched
+over to DSP ownership.