User manual

DocID025833 Rev 3 21/49

UM1724 Hardware layout and configuration

5.7 OSC clock

5.7.1 OSC clock supply

There are three ways to manage the external high-speed clock (HSE):

 MCO from ST-LINK: from MCO of the ST-LINK MCU (U2 on schematic). This

frequency cannot be changed, it is fixed at 8 MHz and connected to PF0/PD0/PH0-

OSC_IN of STM32 microcontroller.

The following configuration is needed:

– SB54, SB55 OFF

– R35,R37 removed

– SB16, SB50 ON

 HSE oscillator on-board from X3 crystal (not provided): for typical frequencies and

its capacitors and resistors, please refer to STM32 microcontroller datasheet. The X3

crystal has the following characteristics: 8 MHz, 16PF, 20PPM, and DIP footprint.

The following configuration is needed:

– SB54, SB55 OFF

– R35, R37 soldered

– C33, C34 soldered with 20pF capacitors

– SB16, SB50 OFF

 Oscillator from external PF0/PD0/PH0: from an external oscillator through pin 29 of

the CN7 connector.

The following configuration is needed:

– SB55 ON

– SB50 OFF

– R35,R37 removed

If PF0/PD0/PH0 and PF1/PD1/PH1 are used as GPIOs instead being used as a clock:

– SB54 and SB55 are ON,

– R35 and R37 are removed, and

– SB50 (MCO) is OFF (default configuration).

Part number example: 9SL8000016AFXHF0

Manufacturer: Hong Kong X'tals Limited

Website: http://www.hongkongcrystal.com/en/index.php