MCBSTM32EXL Keil, MCBSTM32EXL Datasheet - Page 109

• Manufacturer Part Number: MCBSTM32EXL
• Description: BOARD EVALUATION FOR STM32F103ZE
• Manufacturer: Keil

Specifications of MCBSTM32EXL

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

RM0008
7.2.2
Figure 12. HSE/ LSE clock sources
External source (HSE bypass)
In this mode, an external clock source must be provided. It can have a frequency of up to
50 MHz. You select this mode by setting the HSEBYP and HSEON bits in the
register
cycle has to drive the OSC_IN pin while the OSC_OUT pin should be left hi-Z. See
Figure
External crystal/ceramic resonator (HSE crystal)
The 3 to 25 MHz external oscillator has the advantage of producing a very accurate rate on
the main clock.
The associated hardware configuration is shown in
characteristics section of the datasheet for more details.
The HSERDY flag in the
external oscillator is stable or not. At startup, the clock is not released until this bit is set by
hardware. An interrupt can be generated if enabled in the
(RCC_CIR).
The HSE Crystal can be switched on and off using the HSEON bit in the
register
HSI clock
The HSI clock signal is generated from an internal 8 MHz RC Oscillator and can be used
directly as a system clock or divided by 2 to be used as PLL input.
The HSI RC oscillator has the advantage of providing a clock source at low cost (no external
components). It also has a faster startup time than the HSE crystal oscillator however, even
with calibration the frequency is less accurate than an external crystal oscillator or ceramic
resonator.
Crystal/ceramic
External clock
Clock source
resonators
12.
(RCC_CR). The external clock signal (square, sinus or triangle) with ~50% duty
(RCC_CR).
Clock control register (RCC_CR)
Doc ID 13902 Rev 9
Connectivity line devices: reset and clock control (RCC)
External
Hardware configuration
source
C
L1
OSC_IN OSC_OUT
Figure
capacitors
OSC_OUT
Load
Clock interrupt register
indicates if the high-speed
(HiZ)
12. Refer to the electrical
C
L2
Clock control
Clock control
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