Osc Clock; Osc Clock Supply; Osc 32 Khz Clock Supply - ST STM32F072 User Manual

Hardware layout
5.12

OSC clock

By default, the STM32F072RBT6 clock source is the high-speed internal (HSI) RC
oscillator. Other clock sources are described hereunder.
5.12.1

OSC clock supply

If PF0 and PF1 are only used as GPIOs instead of clock, then SB17 and SB18 are ON and
R36 and R37 are removed (SB19 must be OFF).
•
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 STM32F072RBT6.
The required configuration is:
–
–
•
Oscillator on board (from X3 crystal, not provided). For typical frequencies and its
capacitors and resistors, refer to the STM32F072RBT6 datasheet.
The required configuration is:
–
–
•
Oscillator from external PF0 (from external oscillator through pin 7 of the P1
connector).
The required configuration is:
–
–
–
5.12.2

OSC 32 KHz clock supply

If PC14 and PC15 are only used as GPIOs instead of clock, then SB13 and SB14 are ON,
and R34 and R35 are removed.
•
Oscillator on board (from X2 crystal, not provided).
The required configuration is:
–
–
• Oscillator from external PC14 (from external oscillator trough the pin 5 of P1
connector).
The required configuration is:
–
–
18/27
SB19 ON and SB17 OFF
R36 removed
SB17, SB18, SB19 OFF
X3, R36, R37, C22, C23 soldered
SB17 ON
SB19 OFF
R36 removed
SB13, SB14 OFF
X2, C19, C20, R34, R35 soldered
SB14 ON
R35 removed
UM1690 Rev 3
UM1690