BKM-10R Protocol
Version 1 - May 16, 2016
License: CC0

The BKM-10R is a remote control used for Sony BVM CRT televisions. It is
required to control some CRTs without built in control, such as the BVM-20F1U.

The protocol is vaguely similar to the one used to control Sony VCRs:
ftp://ftp.sgi.com/sgi/video/rld/vidpage/s9pin.html

This document currently only applies to the CONTROL connection, not to the
REMOTE 1 input/output, though it's expected that they are similar.

== Pinout ==

The remote control and CRT are connected with straight through male-male DE9
cable.

Female DB-9, BKM-10R side:
1. GND
2. /TXD
3. RXD
4. GND
5. +5V
6. GND
7. TXD
8. /RXD
9. GND

Since a straight through cable is used, TXD on the remote side is RXD on the
CRT side. +5V is supplied from the CRT to power the remote.

== Protocol ==

Full duplex RS-422, 38400 baud, 8N1 (the Sony VCR protocol uses odd parity, but
that seems not to be the case here). If you only want to control the CRT,
half duplex RS-485 is electrically compatible.

== Bank ==

There are multiple "banks" that can be switched via 3 byte commands:
0x49 0x45 0x4E - "IEN" - encoders
0x49 0x53 0x57 - "ISW" - switches
0x49 0x4C 0x45 - "ILE" - leds
0x49 0x43 0x43 - "ICC" - ??
0x49 0x4d 0x54 - "IMT" - ??

The remote lazily switches banks when needed.

== Keypresses ==

Each keydown sends 0x44, then group, then mask.
0x44 <group> <mask>

The SHIFT key is "just another key" - state is kept on the CRT. Shifted labels
are listed after non-shifted labels.

You must be in the "ISW" bank first.

<group> <mask> - label
0x03 0x01 - SHIFT
0x03 0x02 - OVERSCAN / 16:9
0x03 0x04 - HORIZ SYNC VIEW / SYNC
0x03 0x08 - VERT SYNC VIEW / BLUE ONLY
0x03 0x10 - MONO / R
0x04 0x01 - APT / G
0x04 0x02 - COMB / B
0x04 0x04 - F1 / F3
0x04 0x08 - F2 / F4
0x04 0x10 - SAFE AREA / ADDRESS
0x02 0x40 - UP
0x02 0x80 - DOWN
0x02 0x10 - MENU
0x02 0x20 - ENTER
0x02 0x08 - PHASE MANUAL
0x02 0x04 - CHROMA MANUAL
0x02 0x02 - BRIGHT MANUAL
0x02 0x01 - CONTRAST MANUAL
0x00 0x01 - 0
0x00 0x02 - 1
0x00 0x04 - 2
0x00 0x08 - 3
0x00 0x10 - 4
0x00 0x20 - 5
0x00 0x40 - 6
0x00 0x80 - 7
0x01 0x01 - 8
0x01 0x02 - 9
0x01 0x04 - Del
0x01 0x08 - Ent
0x01 0x10 - POWER (but see below)
0x01 0x20 - DEGAUSS

== POWER ==

You only need to send a POWER keypress to turn on the monitor, but for some
reason the remote does more.

Power sends five 3-byte sequences:
0x49 0x53 0x57 - switch bank
0x44 0x01 0x10 - POWER switch
(1s pause)
0x49 0x43 0x43 - CC bank?
0x49 0x4d 0x54 - MT bank?
0x44 0x33 0x31 - switch?

CRT responds with:
0x49 0x43 0x43 - CC bank?
<full led state report>
0x49 0x4d 0x54 - MT bank?
<full led state report>

== Encoders ==

Dials are rotary encoders that send 3 bytes:
0x44 <encoder id id> <ticks>

Ticks is a two's complement byte indicating how far the dial has turned since
the last message. The remote sends messages about every 100ms when the dial
is turning.

You must be in the "IEN" bank first.

0x03 - PHASE
0x02 - CHROMA
0x01 - BRIGHT
0x00 - CONTRAST

== LEDs ==

LEDs use the same groups and masks as keypresses. Every time the CRT needs to
change the lights, it changes to the LED bank:

0x49 0x4c 0x45

then sends changed switch groups:

0x44 <group> <mask>

where <mask> is all of the active LED masks OR'd together.

== Memory Card ==

Nobody cares.