Osc Clock; Osc Clock Supply; Osc 32 Khz Clock Supply - ST STM32F051R8T6 User Manual

Hardware and layout
4.7

OSC clock

4.7.1

OSC clock supply

PF0 and PF1 can be used as GPIO or as HSE oscillator. By default these I/Os are
configured as GPIO, so SB16 and SB17 are closed, SB18 is open and R22, R23, C13 and
C14 are not populated.
An external HSE clock can be provided to the MCU in three ways:
MCO from ST-LINK. From MCO of the STM32F103. This frequency cannot be
●
changed, it is fixed at 8 MHz and connected to PF0-OSC_IN of the STM32F051R8T6.
Configuration needed:
–
–
–
Oscillator onboard. From X2 crystal (not provided). For typical frequencies and its
●
capacitors and resistors, please refer to the STM32F051R8T6 Datasheet.
Configuration needed:
–
–
Oscillator from external PF0. From external oscillator through pin 7 of the P1
●
connector. Configuration needed:
–
–
–
4.7.2

OSC 32 KHz clock supply

PC14 and PC15 can be used as GPIO or as LSE oscillator. By default these I/Os are
configured as GPIO, so SB20 & SB21 are closed and X3, R24, R25 are not populated.
An external LSE clock can be provided to the MCU in two ways:
Oscillator onboard. From X3 crystal (not provided). Configuration needed:
●
–
–
Oscillator from external PC14. From external oscillator trough the pin 5 of P1
●
connector. Configuration needed:
–
–
18/41
SB16, SB18 CLOSED
R22, R23 removed
SB17 OPEN
SB16, SB17 SB18 OPEN
R22, R23, C13, C14 soldered
SB16, SB17 CLOSED
SB18 OPEN
R22 and R23 removed
SB20, SB21 OPEN
C15, C16, R24 and R25 soldered.
SB20, SB21 CLOSED
R24 and R25 removed
Doc ID 022910 Rev 2
UM1525