Turns out that, to save power, most peripherals start, that is right after boot, in a powered off state.
The Reset and Clock Control (
RCC) peripheral can be used to power on or off
every other peripheral.
You can find the list of registers in the
RCC register block in:
Section 9.4.14 - RCC register map - Page 166 - Reference Manual
The registers that control the power status of other peripherals are:
Each bit in these registers controls the power status of a single peripheral,
Your task in this section is to power on the
GPIOE peripheral. You'll have to:
- Figure out which of the three registers I mentioned before has the bit that controls the power status.
- Figure out what value that bit must be set to,
1, to power on the
- Finally, you'll have to change the starter code to modify the right
register to turn on the
If you are successful, you'll see that the
gpioe.odr.write statement will now
be able to modify the value of the
Note that this won't be enough to actually turn on the LEDs.