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DIGIC 8 Register Map:


Controls physical UART connection.

Address Description

UART is connected to physical ICU UART on external debug connector. Handled by uart_change command on drysh.

0x0 selects ICU (DryOS on ARM core), 0x2 for CCLIME (DryOS on Xtensa core, network).


Address Description
0xD030422C ??
0xD0304230 VRAM pointer
0xD0304234 VRAM pitch
0xD0304238 Resolution
0xD030423C ??

LV peaking (Highlights / zebra)

Address Output Type Controls what?
0xD0300520 HDMI zebra enable / disable
0xD0300750 HDMI overexpo threshold and style
0xD0300754 HDMI overexpo color
0xD0300758 HDMI underexpo threshold and style
0xD030075C HDMI underexpo color
0xD0304220 LCD/EVF zebra enable / disable
0xD0304488 LCD/EVF overexpo threshold and style
0xD030448C LCD/EVF overexpo color
0xD0304490 LCD/EVF underexpo threshold and style
0xD0304494 LCD/EVF underexpo color

Registers used by DispVram State object to control overexposure highlighting feature.

Different addresses and slightly different values than Digic 6/7, but capabilities are very similar.

It is possible to have independent zebras configured on LCD and HDMI while running in Clean HDMI mode!

Note on directly writing the registers

Directly writing some registers doesn't work (values are overridden). On R170.739 that happens for HDMI enable register, but this seems to differ from model to model. See DIGIC 6 Register Map: for more info.

TL;DR is that you need to find (via xrefs / static code analysis) where reg value is stored, and update that memory address instead.

Enable register

reg & 0x100 controls if highlight is enabled or not.

Value written should be masked 0x100 with one read from reg + 0x2000

This register lies in Display registers range and most likely has more meanings.

Threshold / style register

**** **** **** **** **** **** **** ****
*... .... .... .... .... .... .... .... visibility (on/off)
..** .... .... .... .... .... .... .... stripes move speed (0-3)
.... ...* .... .... .... .... .... .... stripes angle (45 / -45 deg)
.... .... ..** .... .... .... .... .... stripes style
.... .... .... .*** .... .... .... .... stripes opacity
.... .... .... .... **** **** .... .... threshold (underexpo)
.... .... .... .... .... .... **** **** threshold (overexpo)

Value written should be masked 0xB137FFFF with one read from reg + 0x2000

Field Range Description
visibility 0,1 zebra visibility (do not confuse with Enable register)
speed 0-3 lines/dots are moving slower → faster
angle 0-1 0: 45 deg, 1: -45 deg
style 0-2 0: light dots, 1: thin lines, 2: thick lines
opacity 0-7 very opaque → solid color
underexpo_th 0-255 Threshold on undexexpo register, ignored on overexpo
overexpo_th 0-255 Threshold on overexpo register, ignored on underexpo

Note: On HDMI max threshold is 0xE8 Values above that are not displayed!

Color register

Controls color of highlight overlays. ??YYUUVV format. Canon code defaults to black (00008080)

More registers

Code suggests there are more registers:

Output Reg Addresses Range
HDMI Enable 0xD0300520 + 0x30 * n n∈⟨0,7⟩
LCD Enable 0xD0304220 + 0x30 * n n∈⟨0,7⟩
HDMI Threshold 0xD0300750 + 0x8 * m m∈⟨0,5⟩
HDMI Color 0xD0300754 + 0x8 * m m∈⟨0,5⟩
LCD Threshold 0xD0304488 + 0x8 * m m∈⟨0,5⟩
LCD Color 0xD030448C + 0x8 * m m∈⟨0,5⟩

n values above 0 and m values above 1 are not understood. There's no visible difference on screen.

For m > 1 Threshold registers accept both under and overexposure thresholds at the same time, but since those have no visible effects on displayed image - meaning is unknown.

Guess: maybe m > 1 are in use for 10 bit / HDR mode?


Address Description
0xD800021D Left Microphone Level and Peak
0xD8000220 Right Microphone Level and Peak
digic8/registers.txt · Last modified: 2022/02/21 23:03 by kitor