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/Documentation/sound/alsa/serial-u16550.txt

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 1
 2			Serial UART 16450/16550 MIDI driver
 3			===================================
 4
 5The adaptor module parameter allows you to select either:
 6
 7  0 - Roland Soundcanvas support (default)
 8  1 - Midiator MS-124T support (1)
 9  2 - Midiator MS-124W S/A mode (2)
10  3 - MS-124W M/B mode support (3)
11  4 - Generic device with multiple input support (4)
12
13For the Midiator MS-124W, you must set the physical M-S and A-B
14switches on the Midiator to match the driver mode you select.
15
16In Roland Soundcanvas mode, multiple ALSA raw MIDI substreams are supported
17(midiCnD0-midiCnD15).  Whenever you write to a different substream, the driver
18sends the nonstandard MIDI command sequence F5 NN, where NN is the substream
19number plus 1.  Roland modules use this command to switch between different
20"parts", so this feature lets you treat each part as a distinct raw MIDI
21substream. The driver provides no way to send F5 00 (no selection) or to not
22send the F5 NN command sequence at all; perhaps it ought to.
23
24Usage example for simple serial converter:
25
26	/sbin/setserial /dev/ttyS0 uart none
27	/sbin/modprobe snd-serial-u16550 port=0x3f8 irq=4 speed=115200
28
29Usage example for Roland SoundCanvas with 4 MIDI ports:
30
31	/sbin/setserial /dev/ttyS0 uart none
32	/sbin/modprobe snd-serial-u16550 port=0x3f8 irq=4 outs=4
33
34In MS-124T mode, one raw MIDI substream is supported (midiCnD0); the outs
35module parameter is automatically set to 1. The driver sends the same data to
36all four MIDI Out connectors.  Set the A-B switch and the speed module
37parameter to match (A=19200, B=9600).
38
39Usage example for MS-124T, with A-B switch in A position:
40
41	/sbin/setserial /dev/ttyS0 uart none
42	/sbin/modprobe snd-serial-u16550 port=0x3f8 irq=4 adaptor=1 \
43			speed=19200
44
45In MS-124W S/A mode, one raw MIDI substream is supported (midiCnD0);
46the outs module parameter is automatically set to 1. The driver sends
47the same data to all four MIDI Out connectors at full MIDI speed.
48
49Usage example for S/A mode:
50
51	/sbin/setserial /dev/ttyS0 uart none
52	/sbin/modprobe snd-serial-u16550 port=0x3f8 irq=4 adaptor=2
53
54In MS-124W M/B mode, the driver supports 16 ALSA raw MIDI substreams;
55the outs module parameter is automatically set to 16.  The substream
56number gives a bitmask of which MIDI Out connectors the data should be
57sent to, with midiCnD1 sending to Out 1, midiCnD2 to Out 2, midiCnD4 to
58Out 3, and midiCnD8 to Out 4.  Thus midiCnD15 sends the data to all 4 ports.
59As a special case, midiCnD0 also sends to all ports, since it is not useful
60to send the data to no ports.  M/B mode has extra overhead to select the MIDI
61Out for each byte, so the aggregate data rate across all four MIDI Outs is
62at most one byte every 520 us, as compared with the full MIDI data rate of
63one byte every 320 us per port.
64
65Usage example for M/B mode:
66
67	/sbin/setserial /dev/ttyS0 uart none
68	/sbin/modprobe snd-serial-u16550 port=0x3f8 irq=4 adaptor=3
69
70The MS-124W hardware's M/A mode is currently not supported. This mode allows
71the MIDI Outs to act independently at double the aggregate throughput of M/B,
72but does not allow sending the same byte simultaneously to multiple MIDI Outs. 
73The M/A protocol requires the driver to twiddle the modem control lines under
74timing constraints, so it would be a bit more complicated to implement than
75the other modes.
76
77Midiator models other than MS-124W and MS-124T are currently not supported. 
78Note that the suffix letter is significant; the MS-124 and MS-124B are not
79compatible, nor are the other known models MS-101, MS-101B, MS-103, and MS-114.
80I do have documentation (tim.mann@compaq.com) that partially covers these models,
81but no units to experiment with.  The MS-124W support is tested with a real unit.
82The MS-124T support is untested, but should work.
83
84The Generic driver supports multiple input and output substreams over a single
85serial port.  Similar to Roland Soundcanvas mode, F5 NN is used to select the
86appropriate input or output stream (depending on the data direction).
87Additionally, the CTS signal is used to regulate the data flow.  The number of
88inputs is specified by the ins parameter.