ST NUCLEO-H745ZI-Q, User Manual

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Hardware layout and configuration UM2408
28/45 UM2408 Rev 1
the oscillator design guide. The X2 crystal has the following characteristics: 25 MHz,
6 pF, 20 ppm. It is recommended to use NX2016SA-25MHz-EXS00A-CS11321
manufactured by NDK. The configuration must be:
–
SB71 and SB90 OFF
– SB3 and SB4 ON
– C74 and C76 soldered with 5.1 pF capacitors
– SB72 OFF
Oscillator from external PH0: from an external oscillator through the pin 29 of the CN11
connector. The configuration must be:
– SB71 ON
– SB72 OFF
– SB3 and SB4 removed
•
HSE not used: PH0 and PH1 are used as GPIOs instead of clock. The configuration
must be:
–
SB71 and SB90 ON
– SB72 (MCO) OFF
– SB3 and SB4 removed
6.9.2 OSC 32 KHz
There are three ways to configure the pins corresponding to low-speed clock (LSE):
•
On-board oscillator (default): X3 crystal. Refer to the Oscillator design guide for
STM8S, STM8A and STM32 microcontrollers Application note (AN2867) for oscillator
design guide for STM32H7 microcontrollers. It is recommended to use NX3215SA-
32.768KHZ EXS00A-MU00525 (32.768 kHz, 6 pf load capacitance, 20 ppm) from
NDK.
•
Oscillator from external PC14: from external oscillator through the pin 25 of CN11
connector. The configuration must be:
–
SB66 and SB67 ON
– R41 and R42 removed
•
LSE not used: PC14 and PC15 are used as GPIOs instead of low-speed clock. The
configuration must be:
–
SB66 and SB67 ON
– R41 and R42 removed
6.10 USART communication
The USART3 interface available on PD8 and PD9 of the STM32H7 can be connected either
to ST-LINK or to ST morpho connector. The choice is changed by setting the related solder
bridges. By default, the USART3 communication between the target STM32H7 and the
STLINK is enabled, to support the Virtual COM port for the Mbed (SB16 and SB17 ON).