FreeCalypso > hg > freecalypso-schem2
annotate venus/src/core/int_vcxo_passive.v @ 23:9f70dc110ad7
venus/src/usb: building blocks from DUART28
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Sat, 20 Nov 2021 17:48:18 +0000 |
parents | 3ed0f7a9c489 |
children | d0b6c4915397 |
rev | line source |
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9
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
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1 /* |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
2 * This module captures the mysterious all-passive circuit between Iota's |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
3 * AFC output and Rita's XIN input as depicted on the Leonardo schematics. |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
4 * This circuit defies understanding, but it appears in Openmoko's GSM |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
5 * modem (unchanged from Leonardo) and that modem works, hence we deem |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
6 * this voodoo circuit to be suitable for mindless copying w/o understanding... |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
7 * |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
8 * Note that C205 is not included here, as it's already been included |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
9 * in the abb_block wrapper instead. |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
10 */ |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
11 |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
12 module int_vcxo_passive (AFC_in, XIN_connection, GND); |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
13 |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
14 input AFC_in, GND; |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
15 inout XIN_connection; |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
16 |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
17 wire R217_to_xtal, xtal_to_R211, R211_to_C225; |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
18 |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
19 resistor R217 (AFC_in, R217_to_xtal); |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
20 varactor_diode D200 (.Cathode(R217_to_xtal), .Anode(GND)); |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
21 capacitor C226 (R217_to_xtal, GND); |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
22 xtal_4pin_pkg xtal (.pin_1(xtal_to_R211), .pin_2(GND), |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
23 .pin_3(R217_to_xtal), .pin_4(GND)); |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
24 resistor R211 (xtal_to_R211, R211_to_C225); |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
25 capacitor C224 (R211_to_C225, GND); |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
26 capacitor C225 (R211_to_C225, XIN_connection); |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
27 |
3ed0f7a9c489
Venus: first version of Verilog for the Calypso core
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
28 endmodule |