FreeCalypso > hg > freecalypso-reveng
comparison pirelli/audio @ 56:fdfb57a1c5fe
Pirelli PCB tracing: voice band i/f, MCSI and MODEM UART
| author | Michael Spacefalcon <msokolov@ivan.Harhan.ORG> |
|---|---|
| date | Sun, 20 Oct 2013 04:49:28 +0000 |
| parents | 037c9bea954c |
| children | 2bec477178fc |
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| 55:037c9bea954c | 56:fdfb57a1c5fe |
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| 15 but they appear to go to vias at (1935,218) and (1934,260). Found them on L3: | 15 but they appear to go to vias at (1935,218) and (1934,260). Found them on L3: |
| 16 going to new vias at (3703,311) and (3739,313). (It might actually be L4.) | 16 going to new vias at (3703,311) and (3739,313). (It might actually be L4.) |
| 17 Found them on L7: fat traces to micro-vias at (3870,934) and (3898,869). | 17 Found them on L7: fat traces to micro-vias at (3870,934) and (3898,869). |
| 18 Finally on L8 they go to the Winbond chip! The speaker connection pins appear | 18 Finally on L8 they go to the Winbond chip! The speaker connection pins appear |
| 19 to be the two leftmost ones in the top row of 9 pins. | 19 to be the two leftmost ones in the top row of 9 pins. |
| 20 | |
| 21 Calypso-Iota Voice Band interface | |
| 22 | |
| 23 Tracing the Calypso voice output signal, starting from Calypso ball P14 (VDX). | |
| 24 On L1 it goes to a via at (3401,429). On L2 it branches: one end goes to | |
| 25 (3366,304) - suspected via back to L1 for a test point, and the other end goes | |
| 26 to (2885,917) - also a suspected via back to L1. Found the 1st branch on L1: | |
| 27 it's a short trace to another via at (3291,304). Found the 2nd branch on L1 | |
| 28 too: it goes to Iota ball F5 (VDR), matching the Leonardo schematics. | |
| 29 | |
| 30 Now let's trace the branch that went to (3291,304) on L1. On L2 it goes to a | |
| 31 short trace that goes to (3349,197) - suspected micro-via back to L1. Looking | |
| 32 on L1: yes, indeed the trace seems to lead back here, but then the edge | |
| 33 grind-down damage gets in the way. Looking at the L1 populated photo, the | |
| 34 trace definitely seems to go to an exposed test point. | |
| 35 | |
| 36 The apparent lack of a switch or MUX on the Iota digital voice input strongly | |
| 37 suggests that in Wi-Fi VoIP operation the Calypso DSP acts as a forwarder for | |
| 38 the digital voice samples, which are being fed to it from the VoIP chip via | |
| 39 another interface: MCSI, or perhaps the otherwise unused MODEM UART switched | |
| 40 over to DSP ownership. |