FreeCalypso > hg > fc-small-hw
annotate bb2fc/README @ 47:ba1450b0c956
duart28c MCL: new components added
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Wed, 29 Jul 2020 07:21:04 +0000 |
parents | 0f9bdd60ce50 |
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rev | line source |
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0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
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1 The little board to be built in this project is an adapter for connecting an |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
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2 OMAP BeagleBoard-xM to a FreeCalypso device, specifically connecting Calypso's |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
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3 MCSI to OMAP's McBSP (primary objective) and also connecting a 4-wire UART |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
4 (data + hw flow control) between the two devices - BB expansion interface |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
5 provides such a UART, and it costs us very little extra effort to connect it |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
6 along with MCSI. |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
7 |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
8 The present adapter will plug into the expansion header on the bottom side of |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
9 the BeagleBoard, implement logic voltage level translation between OMAP's 1.8 V |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
10 and Calypso's 2.8 V using the 1.8 V and 5 V power supplies provided by the |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
11 BeagleBoard, and bring 2.8 V UART and MCSI interfaces out on headers, intended |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
12 to be connected to a FreeCalypso board with jumper wires. |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
13 |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
14 The logic voltage level translation function will be accomplished using two |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
15 74AVC4T774PW ICs, one for the UART and one for MCSI. As a somewhat arbitrary |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
16 pick made for greater ease of PCB layout, the A side of each translating |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
17 transceiver IC will be the 2.8 V side and the B side will be the 1.8 V side. |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
18 Each of the 4 1-bit channels in the 74AVC4T774PW has its own direction control |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
19 pin, allowing us to neatly use one of these ICs for each 4-wire interface |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
20 despite mixed signal directions. MCSI_CLK and MCSI_FSYNCH are assumed to be |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
21 outputs from the Calypso like they are when driven by the DSP ROM code in the |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
22 silicon, and they will be voltage-translated in the Calypso to OMAP direction; |
0f9bdd60ce50
fc-small-hw separated from old freecalypso-schem repo
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
23 the other direction is NOT supported. |