User manual

DocID025833 Rev 9 19/61
UM1724 Hardware layout and configuration
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– R35 and R37 removed
• HSE not used: PF0/PD0/PH1 and PF1/PD1/PH1 are used as GPIO instead of Clock
The following configuration is needed:
– SB54 and SB55 ON
– SB16 and SB50 (MCO) OFF
– R35 and R37 removed
There are two possible default configurations of the HSE pins depending on the version of
NUCLEO board hardware.
The board version MB1136 C-01 or MB1136 C-02 is mentioned on sticker placed on bottom
side of the PCB.
The board marking MB1136 C-01 corresponds to a board, configured for HSE not used.
The board marking MB1136 C-02 (or higher) corresponds to a board, configured to use ST-
LINK MCO as clock input.
Note: For NUCLEO-L476RG the ST-Link MCO output is not connected to OSCIN to reduce power
consumption in low power mode. Consequently NUCLEO-L476RG configuration
corresponds HSE not used.
5.6.2 OSC 32 kHz clock supply
There are three ways to configure the pins corresponding to low-speed clock (LSE):
• On-board oscillator: X2 crystal. Please refer to the AN2867 for oscillator design guide
for STM32 microcontrollers.ABS25-32.768KHZ-6-T manufactured by Abracon
corporation.
• Oscillator from external PC14: from external oscillator through the pin 25 of CN7
connector.
The following configuration is needed:
– SB48 and SB49 ON
– R34 and R36 removed
• LSE not used: PC14 and PC15 are used as GPIOs instead of low speed Clock.
The following configuration is needed:
– SB48 and SB49 ON
– R34 and R36 removed
There are two possible default configurations of the LSE depending on the version of
NUCLEO board hardware.
The board version MB1136 C-01 or MB1136 C-02 is mentioned on sticker placed on bottom
side of the PCB.
The board marking MB1136 C-01 corresponds to a board configured as LSE not used.
The board marking MB1136 C-02 (or higher) corresponds to a board configured with on-
board 32kHz oscillator.
The board marking MB1136 C-03 (or higher) corresponds to a board using new LSE crystal
(ABS25) and C26, C31 & C32 value update.