Clock tree for GD32F103VET6
The GD32F103xx device is a 32-bit general-purpose microcontroller based on the Arm® Cortex®-M3 RISC core with best ratio in terms of processing power, reduced power consumption and peripheral set. The Cortex®-M3 is a next generation processor core which is tightly coupled with a Nested Vectored Interrupt Controller (NVIC), SysTick timer and advanced debug support.
Low speed external clock (LXTAL) generated from a crystal characteristics(For GD32F103x4/6/8/B devices)
RTC 32.768KHz for GD32F103VET6
CLXTAL1 = CLXTAL2 = 2*(CLOAD – CS), For CLXTAL1 and CLXTAL2, it is recommended matching capacitance on OSC32IN and OSC32OUT. For CLOAD, it is crystal/ceramic load capacitance, provided by the crystal or ceramic manufacturer. For CS, it is PCB and MCU pin stray capacitance.
Real time clock (RTC)
- 32-bit up-counter with a programmable 20-bit prescaler
- Alarm function
- Interrupt and wake-up event
The real time clock is an independent timer which provides a set of continuously running counters which can be used with suitable software to provide a clock calendar function, and provides an alarm interrupt and an expected interrupt. The RTC features a 32-bit programmable counter for long-term measurement using the compare register to generate an alarm. A 20-bit prescaler is used for the time base clock and is by default configured to generate a time base of 1 second from a clock at 32.768 KHz from external crystal oscillator.
拓展阅读：
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