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                                样例使用说明
                             Sample Description
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功能描述：
此样例演示了使用TIM1产生“六步PWM信号”，每间隔1ms在SysTick中断中触发换向，实现无刷
电机的换向。

Function descriptions:
This sample demonstrates how TIM1 can be used to generate a "six-step PWM signal."
The commutation is triggered in the SysTick interrupt every 1ms to realize the
commutation of the brushless motor.
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测试环境：
测试用板：PY32F403_STK
MDK版本： 5.28
IAR版本： 9.20
GCC 版本：GNU Arm Embedded Toolchain 10.3-2021.10

Test environment:
Test board: PY32F403_STK
MDK Version: 5.28
IAR Version: 9.20
GCC Version: GNU Arm Embedded Toolchain 10.3-2021.10
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使用步骤：
1. 编译下载程序到MCU，并运行
2. 使用逻辑分析仪观察引脚PA8/PA9/PA10/PB13/PB14/PB15的波形

Example execution steps:
1. compile and download the program to MCU and run it;
2. Observe PA8/PA9/PA10/PB13/PB14/PB15 waveforms with logic analyzer
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注意事项：
换向步骤和波形如下所示：
                第一步  第二步  第三步  第四步  第五步  第六步     
CH1               1       0       0      0        0       1        
CH1N              0       0       1      1        0       0        
CH2               0       0       0      1        1       0        
CH2N              1       1       0      0        0       0        
CH3               0       1       1      0        0       0        
CH3N              0       0       0      0        1       1        

CH1  (PA08)   |||||||_________________________________|||||||
CH1N (PB13)   _______________||||||||||||||||________________
                                  
CH2  (PA09)   _______________________||||||||||||||||________
CH2N (PB14)   |||||||||||||||________________________________
                                  
CH3  (PA10)   _______||||||||||||||||________________________
CH3N (PB15)   ________________________________|||||||||||||||

Notes:
The commutation steps and waveforms are shown below:
                step 1  step 2  step 3 step 4   step 5  step 6
CH1               1       0       0      0        0       1
CH1N              0       0       1      1        0       0
CH2               0       0       0      1        1       0
CH2N              1       1       0      0        0       0
CH3               0       1       1      0        0       0
CH3N              0       0       0      0        1       1

CH1  (PA08)   |||||||_________________________________|||||||
CH1N (PB13)   _______________||||||||||||||||________________
           
CH2  (PA09)   _______________________||||||||||||||||________
CH2N (PB14)   |||||||||||||||________________________________
           
CH3  (PA10)   _______||||||||||||||||________________________
CH3N (PB15)   ________________________________|||||||||||||||
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