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DevBee
DevBee
Associate III
Feb 11, 2020 12:56 PM UTC
Solved

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

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.

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waclawek.jan
waclawek.janBest answer
Super User
Feb 11, 2020 4:56 PM UTC

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

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waclawek.jan
waclawek.janBest answer
Super User
Feb 11, 2020 4:56 PM UTC

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

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