RM0444 Rev 5 167/1390
RM0444 Reset and clock control (RCC)
220
5.2.1 HSE clock
The high speed external clock signal (HSE) can be generated from two possible clock
sources:
• HSE external crystal/ceramic resonator
• HSE user external clock
The resonator and the load capacitors have to be placed as close as possible to the
oscillator pins in order to minimize output distortion and startup stabilization time. The
loading capacitance values must be adjusted according to the selected oscillator.
Figure 11. HSE/ LSE clock sources
Clock source Hardware configuration
External clock
Crystal/Ceramic
resonators
OSC_OUT
External
source
GPIO
OSC_IN
(OSC_EN as AF)
OSC_IN OSC_OUT
Load
capacitors
C
L2
C
L1