FreeCalypso > hg > freecalypso-schem2

annotate venus/doc/Star-points-in-core @ 35:971c05950675

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
starpoints in core: commit to using pcb-rnd intnoconn
author Mychaela Falconia <falcon@freecalypso.org>
date Mon, 22 Nov 2021 09:54:48 +0000
parents
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
35
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
1 iWOW's TR-800 module, whose reverse-engineered PCB layout will serve as a
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
2 reference for the Calypso core of FC Venus, is nothing but a mass-produced
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
3 version of TI's Leonardo reference design. We don't have any original PCB
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
4 layout files for Leonardo, but we do have schematics, in 3 different versions:
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
5
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
6 ftp://ftp.freecalypso.org/pub/GSM/Calypso/Leonardo_plus_RD122.pdf
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
7 ftp://ftp.freecalypso.org/pub/GSM/Calypso/Leonardo_plus_quadband_schem.pdf
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
8 ftp://ftp.freecalypso.org/pub/GSM/Calypso/Leonardo_rev05.pdf
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
9
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
10 TR-800 is based on quadband Leonardo+ (that's what makes it interesting), but
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
11 the hobbled 2-band version of Leonardo is the only one for which we have TI's
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
12 original DSN (OrCAD) schematic file, in addition to the corresponding PDF:
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
13
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
14 ftp://ftp.freecalypso.org/pub/GSM/Calypso/Leonardo_rev05.dsn
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
15
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
16 TI's group in Aalborg (Denmark) that designed and built their development boards
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
17 used OrCAD for schematics and PADS for PCB layout. We have their PADS PCB
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
18 design file for a different board from about the same time frame (E-Sample),
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
19 but not for any Leonardo variant.
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
20
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
21 If you look at the baseband page of Leonardo schematics (this part is the same
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
22 in all 3 versions), you will see 3 symbols denoting star routing: HST201 and
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
23 HST202 (labeled "STAR_CONFIG") split V-DBB net into VDD-PLL and VDD-CORE
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
24 branches, and HST203 (labeled "GND_POINT") creates a special ground for the
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
25 32.768 kHz oscillator circuit, connected to the rest of board ground at just
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
26 one point.
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
27
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
28 This star routing in TI's reference version of Calypso/Leonardo core exists not
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
29 only in TI's schematics, but also in the physical PCB layout which we have
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
30 recovered from TR-800 by reverse engineering. If you look at the Gerber files
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
31 which we received from the PCB RE company (published on our FTP site in 2021),
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
32 specifically the OKPCBM~1.G1 gerber file corresponding to the inner layer just
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
33 below the surface (L2 or L5 depending on which way you count), you can see the
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
34 physical features that were once produced, presumably in PADS, to effect the
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
35 star routing depicted in the schematics.
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
36
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
37 The physical PCB star routing feature corresponding to HST201 & HST202 resides
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
38 just underneath C214 footprint. There is a microvia (blind via going only one
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
39 layer in) inside C214 pad 1 (the left pad in the Gerber view), and on the inner
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
40 layer where this microvia goes, one can clearly see the feature that splits the
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
41 V-DBB net coming from C214.1 into VDD-PLL and VDD-CORE branches. The lower (in
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
42 the Gerber view) branch that goes to two microvias back to the surface is
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
43 VDD-PLL, whereas the other branch that goes to an inner buried via (spanning L2
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
44 through L5) is VDD-CORE.
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
45
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
46 The other star routing feature in the TR-800 PCB corresponding to TI's HST203
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
47 can be seen in the far lower right corner of the same OKPCBM~1.G1 gerber file:
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
48 look for an L shape that connects a short thin trace (going to a microvia to the
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
49 surface) to the surrounding GND copper pour. The short thin trace connected to
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
50 the GND copper pour by the L shape is what we named GND_32khz in
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
51 src/core/dbb_block.v, and the L shape on the inner layer is what eventually
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
52 became of HST203.
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
53
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
54 The present ueda netlist source code for FC Venus is written with the
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
55 expectation that the same pseudo-component EDA trick for star routing will be
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
56 used on our board, using intnoconn feature of pcb-rnd:
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
57
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
58 http://repo.hu/cgi-bin/pool.cgi?project=pcb-rnd&cmd=show&node=intnoconn
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
59
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
60 There is one difference in this regard between TI's original version and ours.
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
61 In TI's original version all 3 pseudo-component objects HST201, HST202 and
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
62 HST203 were 2-way stars, with HST201 and HST202 being somehow combined in PADS
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
63 layout to form the desired 3-way star. In our version 3-way star HST200
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
64 explicitly replaces TI's HST201+HST202 pair. The actual pcb-rnd subcircuits
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
65 for the 3-way star HST200 and the 2-way star HST203 will need to be created by
971c05950675 starpoints in core: commit to using pcb-rnd intnoconn
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
66 the PCB layout engineer.