STM32F407 Datasheet section 2.2 Device overview, Figure 5 shows AHB1 in grey filled and some peripherals too filled grey, along with that.

DevBee · ‎2020-02-11

What does the grey filling indicate. Couldn't find any legend/detail covering this.

I initially though it is the part connected to POR/VBAT circuit.. but doesn't look so.

Attached image of the page.

waclawek.jan · ‎2020-02-11

AHB1 is greyed out only to reduce number of lines on that picture and make it distinguishable from other buses; might've been also colored (as is in some newer STM32 DS).

OTOH, the greyed-out boxes, e.g. ADC on left bottom, DAC on bottom, RTC+BKPSRAM on the right, etc. highlight parts, which are not supplied by the internal 1.2V voltage regulator (i.e. are in a different power domain) - note that they always have also the respective supply pin/power domain name written next to them, e.g. @VDDA.

JW

View solution in original post

waclawek.jan · ‎2020-02-11

AHB1 is greyed out only to reduce number of lines on that picture and make it distinguishable from other buses; might've been also colored (as is in some newer STM32 DS).

OTOH, the greyed-out boxes, e.g. ADC on left bottom, DAC on bottom, RTC+BKPSRAM on the right, etc. highlight parts, which are not supplied by the internal 1.2V voltage regulator (i.e. are in a different power domain) - note that they always have also the respective supply pin/power domain name written next to them, e.g. @VDDA.

JW