4f.md

0x4f Monitor Control

GT 0x3b → BMBT 0xf0
TV 0xed → BMBT 0xf0

This command is used to control, and configure the BMBT monitor.

It's very helpful when testing navigation computers, and video modules which might not support automatic encoding, and aspect ratio switching.

Related Commands

• 0x2b Telephone LEDs
• 0x4a Tape Control/Radio LED

Example Frames

# GT
3B 04 F0 4F 10 90       # Monitor on at KL-R
3B 04 F0 4F 00 80       # Select "Monitor Off"

# TV
ED 05 F0 4F 11 12 54    # Open "Television" (On, TV, 16x9, NTSC)
ED 05 F0 4F 12 11 54    # Return to Main Menu (On, Nav. GT, 16x9, PAL)

Parameters

Two byte bitfield, although the second byte is often negated by GT.

# Byte 1
SOURCE       = 0b0000_0011 << 8
POWER        = 0b0001_0000 << 8

# Byte 2 (Optional)
ENCODING     = 0b0000_0011 << 0
ASPECT_RATIO = 0b0011_0000 << 0

Source 0b0000_0011 << 8

SOURCE_NAV_GT = 0b0000_0000
SOURCE_TV     = 0b0000_0001
SOURCE_VID_GT = 0b0000_0010

The input source switching in handled by the video module, but each source has it's own brightness settings which is recalled.

Power 0b0001_0000 << 8

POWER_OFF     = 0b0000_0000
POWER_ON      = 0b0001_0000

This will turn the monitor on, or off accordingly.

The GT will turn the monitor on at ignition position 1 (KL-R), and off at ignitition position 0.

Encoding 0b0000_0011 << 0

ENCODING_NTSC = 0b0000_0001
ENCODING_PAL  = 0b0000_0010

Encoding issues are commonly seen when switching between different generation navigation computers, or video modules, as there did seem to be a switch between PAL and NTSC as the encoding for navigation computer video. Incorrect encoding is usually denoted by "scrolling" video image.

Aspect Radio 0b0011_0000 << 0

ASPECT_4_3    = 0b0000_0000
ASPECT_16_9   = 0b0001_0000
ASPECT_ZOOM   = 0b0011_0000