FreeCalypso > hg > freecalypso-reveng
changeset 10:b0f7481efc8b
Pirelli PCB rev eng: finally have something worthy to report:
traced out the 3 chip selects for the RAM/flash MCP.
author | Michael Spacefalcon <msokolov@ivan.Harhan.ORG> |
---|---|
date | Sat, 20 Apr 2013 00:56:45 +0000 |
parents | 7a84f9e42a84 |
children | a51729642295 |
files | pirelli/calypso pirelli/pcb |
diffstat | 2 files changed, 58 insertions(+), 0 deletions(-) [+] |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/pirelli/calypso Sat Apr 20 00:56:45 2013 +0000 @@ -0,0 +1,45 @@ +Calypso pin I thought was nIBOOT (N1), but actually seems to be A13 (RFEN): +the trace from the ball goes straight down to a via, L1 image coords +(3676,1174). On L2 trace goes to another via at (3234,1074). On L5 it goes +to yet another via at (2950,535). On L4 it goes to (1941,457). On L2 it goes +to a surface via at (1957,484). Back on L1 it goes to Rita pin 2 (XEN). +This arrangement matches what the Rita spec describes as the "external VCTCXO" +configuration. In contrast, the Leonardo schematics depict the "internal +VCTCXO" configuration. + +Double-checking: in the "external VCTCXO" configuration Rita pin 1 (XSEL) is +supposed to be grounded. On L1 the pad appears to go nowhere (isolated). +The central coordinates of the pad on L1 are (1956,638). On L2 there is +solid copper fill in that area. Perhaps there is an invisible micro-via? + +The real nIBOOT pin (N1): stays on L1, a trace takes it to one pad of a +2-pad SMT component, the other pad's connection is unclear (appears isolated, +must be an invisible micro-via). Must be a pull-up/down resistor, hopefully +pull-down. + +nCS0 (C2): L1 trace to (4262,1016). On L2 it goes to two via points: +(4852,1016), an obvious larger via, and (4802,1000), a spot where a micro-via +back to L1 could hide. The micro-via back to L1 appears to be there indeed, +feeding an unmasked test point on the surface. Back to the main trace at +(4852,1016): there's something on L4 (might be a trace to another nearby via), +but maybe it's nothing, just a poor picture. Most likely nothing there, as +the same arrangement appears on L5 and L6, but clearly with no connection +between the two nearby vias. L7 is probably where the interesting connection +is, but the trace appears to have been scraped off in that spot in steve-m's +layer-grinding process. + +Taking a different approach: let's start with the RAM/flash MCP on L8. Flash +CE1# goes to (4911,987); flash CE2# goes to (4954,660) and to an L8 test pad; +OE# goes to (4885,982); RAM CE1# goes to (4860,978). Of the two L2-L7 vias, +the upper one appears to be RAM, and the lower one appears to be flash. + +Mistake found: I had earlier messed up trying to trace nCS0 on L2. Now it's +all clear: nCS0 goes to flash CE1#. + +Now let's trace the RAM CS. From the upper L2-L7 via it goes on L2 to +(4800,1002) - already known to be a test point - and to (4212,978). +On L1 it goes to Calypso pin C3 - nCS1, just like on Leonardo. + +Now let's trace flash CE2#. L7-L8 via at (4954,660); L2-L7 via at (4965,927); +on L2 it goes to (4210,930), on L1 it goes to Calypso ball D3. +That's nCS3.
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/pirelli/pcb Sat Apr 20 00:56:45 2013 +0000 @@ -0,0 +1,13 @@ +The Pirelli DP-L10 PCB appears to have 8 layers. Following the good old DEC +convention, I shall refer to them as L1 through L8. Not knowing the original +designers' intended identification, I have arbitrarily assigned L1 to be the +battery/SIM side and L8 to be the display/keypad side. This numbering direction +makes it easier to work with steve-m's grind-down pictures. + +Via structure: there don't seem to be too many all-the-way-through vias, if +any at all, other than maybe the grounding ones around the edges of the board. +Instead most/all internal vias are blind, spanning from L2 through L7. +At both surfaces there are micro-vias (with many/most of them one can't even +see the hope in steve-m's pictures, only a copper circle which one has to +infer is an "annulus" for a micro-via), and these micro-vias only go one layer +deep: from L1 to L2, and from L8 to L7.