利用stm32的tim3实现4路pwm输出控制步进电机，占空比一定，周期可调，从而实现电机调速4路步进电机pwm_stm32\Lib....................\...\cmsis....................\...\.....\core_cm3.c....................\...\.....\core_cm3.h....................\...\.....\stm32f10x.h....................\...\.....\system_stm32f10x.h....................\...\inc....................\...\...\misc.h....................\...\...\stm32f10x_adc.h....................\...\...\stm32f10x_bkp.h....................\...\...\stm32f10x_can.h....................\...\...\stm32f10x_cec.h....................\...\...\stm32f10x_crc.h....................\...\...\stm32f10x_dac.h....................\...\...\stm32f10x_dbgmcu.h....................\...\...\stm32f10x_dma.h....................\...\...\stm32f10x_exti.h....................\...\...\stm32f10x_flash.h....................\...\...\stm32f10x_fsmc.h....................\...\...\stm32f10x_gpio.h....................\...\...\stm32f10x_i2c.h....................\...\...\stm32f10x_iwdg.h....................\...\...\stm32f10x_pwr.h....................\...\...\stm32f10x_rcc.h....................\...\...\stm32f10x_rtc.h....................\...\...\stm32f10x_sdio.h....................\...\...\stm32f10x_spi.h....................\...\...\stm32f10x_tim.h....................\...\...\stm32f10x_usart.h....................\...\...\stm32f10x_wwdg.h....................\...\src....................\...\...\misc.c....................\...\...\stm32f10x_adc.c....................\...\...\stm32f10x_bkp.c....................\...\...\stm32f10x_can.c....................\...\...\stm32f10x_cec.c....................\...\...\stm32f10x_crc.c....................\...\...\stm32f10x_dac.c....................\...\...\stm32f10x_dbgmcu.c....................\...\...\stm32f10x_dma.c....................\...\...\stm32f10x_exti.c....................\...\...\stm32f10x_flash.c....................\...\...\stm32f10x_fsmc.c....................\...\...\stm32f10x_gpio.c....................\...\...\stm32f10x_i2c.c....................\...\...\stm32f10x_iwdg.c....................\...\...\stm32f10x_pwr.c....................\...\...\stm32f10x_rcc.c....................\...\...\stm32f10x_rtc.c....................\...\...\stm32f10x_sdio.c....................\...\...\stm32f10x_spi.c....................\...\...\stm32f10x_tim.c....................\...\...\stm32f10x_usart.c....................\...\...\stm32f10x_wwdg.c....................\...\startup....................\...\.......\arm....................\...\.......\...\startup_stm32f10x_cl.s....................\...\.......\...\startup_stm32f10x_hd.s....................\...\.......\...\startup_stm32f10x_hd_vl.s....................\...\.......\...\startup_stm32f10x_ld.s....................\...\.......\...\startup_stm32f10x_ld_vl.s....................\...\.......\...\startup_stm32f10x_md.s....................\...\.......\...\startup_stm32f10x_md_vl.s....................\...\.......\...\startup_stm32f10x_xl.s....................\MDK_Project....................\...........\List....................\...........\....\Project.map....................\...........\....\startup_stm32f10x_hd.lst....................\...........\Out....................\...........\...\core_cm3.crf....................\...........\...\core_cm3.d....................\...........\...\core_cm3.o....................\...........\...\main.crf....................\...........\...\main.d....................\...........\...\main.o....................\...........\...\misc.crf....................\...........\...\misc.d....................\...........\...\misc.o....................\...........\...\Project.axf....................\...........\...\Project.hex....................\...........\...\Project.htm....................\...........\...\Project.lnp....................\...........\...\Project.plg....................\...........\...\Project.sct....................\...........\...\Project.tra....................\...........\...\startup_stm32f10x_hd.d....................\...........\...\startup_stm32f10x_hd.o....................\...........\...\stm32f10x_adc.crf....................\...........\...\stm32f10x_adc.d....................\...........\...\stm32f10x_adc.o....................\...........\...\stm32f10x_gpio.crf....................\...........\...\stm32f10x_gpio.d....................\...........\...\stm32f10x_gpio.o....................\...........\...\stm32f10x_i2c.crf....................\...........\...\stm32f10x_i2c.d....................\...........\...\stm32f10x_i2c.o....................\...........\...\stm32f10x_it.crf....................\...........\...\stm32f10x_it.d....................\...........\...\stm32f10x_it.o....................\...........\...\stm32f10x_rcc.crf……