为什么定时器好像不准

Music · 发表于 2016-6-8 11:36:20

下面是1秒周期的脉冲,占空比%50 没错吧，为什么用keil的逻辑分析仪,却是0.11111s的周期呢

[mw_shl_code=applescript,true]TIM_TimeBaseInitTypeDef TIM_JGT;
TIM_OCInitTypeDef TIM_OCJGT;

GPIO_PinRemapConfig(GPIO_Remap_TIM4,DISABLE);

TIM_ClearITPendingBit(TIM4,TIM_IT_Update); //Çå3yÖD¶Ï±êÖ¾

//3õÖμ2000±íê¾¶¨ê±1Ãë,1000±íê¾0.5Ãë

TIM_JGT.TIM_Period=2000-1; //¶¨ê±Æ÷3õÖμ 72MHZ/2000=36000 ·ÖÆμ36000 Ôò1Ãë¼Æêy2000′Î 2k
TIM_JGT.TIM_Prescaler=36000-1; //¶¨ê±Æ÷Ô¤·ÖÆμ

TIM_JGT.TIM_CounterMode=TIM_CounterMode_Up; //ÏòéÏ¼ÆêyÄ￡ê½
TIM_JGT.TIM_ClockDivision=0; //·Ö¸î￡¿
TIM_TimeBaseInit(TIM4,&TIM_JGT); //3õê¼»ˉ

TIM_OCJGT.TIM_OCMode=TIM_OCMode_PWM1; //PWMÄ￡ê½1
TIM_OCJGT.TIM_OutputState=TIM_OutputState_Enable; //±è½Ïêä3öê1Äü
TIM_OCJGT.TIM_OCPolarity=TIM_OCPolarity_Low; //¼«DÔÎaμí
TIM_OCJGT.TIM_Pulse=1000-1; //Õ¼¿Õ±èéèÖÃCCR2
TIM_OC2Init(TIM4,&TIM_OCJGT); //í¨μàê1Äü
TIM_OC2PreloadConfig(TIM4, TIM_OCPreload_Enable); //ê1ÄüÔúTIM4ÔúCCR2éÏμÄÔ¤×°ÔØ¼Ä′æÆ÷[/mw_shl_code]