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marcus.erl |
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Serial UART 16450/16550 MIDI driver
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===================================
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The adaptor module parameter allows you to select either:
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1 - Midiator MS-124T support (1)
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2 - Midiator MS-124W S/A mode (2)
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3 - MS-124W M/B mode support (3)
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4 - Generic device with multiple input support (4)
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For the Midiator MS-124W, you must set the physical M-S and A-B
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switches on the Midiator to match the driver mode you select.
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In Roland Soundcanvas mode, multiple ALSA raw MIDI substreams are supported
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(midiCnD0-midiCnD15). Whenever you write to a different substream, the driver
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sends the nonstandard MIDI command sequence F5 NN, where NN is the substream
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number plus 1. Roland modules use this command to switch between different
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"parts", so this feature lets you treat each part as a distinct raw MIDI
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substream. The driver provides no way to send F5 00 (no selection) or to not
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send the F5 NN command sequence at all; perhaps it ought to.
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Usage example for simple serial converter:
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/sbin/setserial /dev/ttyS0 uart none
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/sbin/modprobe snd-serial-u16550 port=0x3f8 irq=4 speed=115200
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Usage example for Roland SoundCanvas with 4 MIDI ports:
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/sbin/setserial /dev/ttyS0 uart none
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/sbin/modprobe snd-serial-u16550 port=0x3f8 irq=4 outs=4
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In MS-124T mode, one raw MIDI substream is supported (midiCnD0); the outs
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module parameter is automatically set to 1. The driver sends the same data to
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all four MIDI Out connectors. Set the A-B switch and the speed module
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parameter to match (A=19200, B=9600).
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Usage example for MS-124T, with A-B switch in A position:
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/sbin/setserial /dev/ttyS0 uart none
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/sbin/modprobe snd-serial-u16550 port=0x3f8 irq=4 adaptor=1 \
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speed=19200
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In MS-124W S/A mode, one raw MIDI substream is supported (midiCnD0);
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the outs module parameter is automatically set to 1. The driver sends
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the same data to all four MIDI Out connectors at full MIDI speed.
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Usage example for S/A mode:
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/sbin/setserial /dev/ttyS0 uart none
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/sbin/modprobe snd-serial-u16550 port=0x3f8 irq=4 adaptor=2
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In MS-124W M/B mode, the driver supports 16 ALSA raw MIDI substreams;
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the outs module parameter is automatically set to 16. The substream
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number gives a bitmask of which MIDI Out connectors the data should be
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sent to, with midiCnD1 sending to Out 1, midiCnD2 to Out 2, midiCnD4 to
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Out 3, and midiCnD8 to Out 4. Thus midiCnD15 sends the data to all 4 ports.
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As a special case, midiCnD0 also sends to all ports, since it is not useful
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to send the data to no ports. M/B mode has extra overhead to select the MIDI
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Out for each byte, so the aggregate data rate across all four MIDI Outs is
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at most one byte every 520 us, as compared with the full MIDI data rate of
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one byte every 320 us per port.
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Usage example for M/B mode:
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/sbin/setserial /dev/ttyS0 uart none
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/sbin/modprobe snd-serial-u16550 port=0x3f8 irq=4 adaptor=3
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The MS-124W hardware's M/A mode is currently not supported. This mode allows
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the MIDI Outs to act independently at double the aggregate throughput of M/B,
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but does not allow sending the same byte simultaneously to multiple MIDI Outs.
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The M/A protocol requires the driver to twiddle the modem control lines under
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timing constraints, so it would be a bit more complicated to implement than
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the other modes.
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Midiator models other than MS-124W and MS-124T are currently not supported.
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Note that the suffix letter is significant; the MS-124 and MS-124B are not
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compatible, nor are the other known models MS-101, MS-101B, MS-103, and MS-114.
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I do have documentation (tim.mann@compaq.com) that partially covers these models,
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but no units to experiment with. The MS-124W support is tested with a real unit.
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The MS-124T support is untested, but should work.
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The Generic driver supports multiple input and output substreams over a single
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serial port. Similar to Roland Soundcanvas mode, F5 NN is used to select the
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appropriate input or output stream (depending on the data direction).
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Additionally, the CTS signal is used to regulate the data flow. The number of
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inputs is specified by the ins parameter.
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