【N32L43x评测】9、互补PWM、死区测试
<p><span style="font-size:24px;">1、前言</span></p><p><span style="font-size:18px;">N32L43X支持两个高级定时器，TIM1和TIM8，高级定时器支持输入捕获、输出比较、PWM、死区、刹车等功能，本文主要测试互补pwm和死区。</span></p>
<p> </p>
<p><span style="font-size:24px;">2、TIM1的pwm通道与互补通道</span></p>
<p><span style="font-size:16px;"> 本文使用PA8和PA7，其中PA8为TIM1的CH1通道，PA7位互补通道。</span></p>
<p> </p>
<p><span style="font-size:24px;">3、死区时间计算</span></p>
<p><strong> 可以看出，死区时间的计算是根据上面的公式的，上面分四种情况来计算死区时间，本文中系统时钟频率为108M，那么可以计算出<span style="font-size:24px;">T</span>DTS=1/108000000=9.26ns；</strong></p>
<p><strong>情况1：DTGN=0xx,那么DTGN的取值范围为0-127，那么DT=（0~127）*9.26ns=（0ns~1176ns）；</strong></p>
<p><strong>情况2：DTGN=10x,那么DTGN的取值范围为0-63，那么DT=（64+DTGN）*2*9.26ns=（64+（0~63））*2*9.26ns=（1185ns~2352ns）；</strong></p>
<p><strong>情况3：DTGN=110,那么DTGN的取值范围为0-31，那么DT=（32+DTGN）*8*2.96ns=（32+（0-31））*8*9.26ns=（2370~4667）；</strong></p>
<p><strong>情况4：DTGN=111,那么DTGN的取值范围为0-31，那么DT=（32+DTGN）*16*2.96ns=（32+（0-31））*16*9.26ns=（4741~9334）；</strong></p>
<p><strong>从上面计算可以看出，在<span style="font-size:24px;">T</span>DTS=9.26ns的时候，最大的死区时间为9334ns=9.3us，</strong></p>
<p> </p>
<p><strong>本文通过设置死区时间为9.3us测试，可以反推出DTGN的值为255，即就是0xff。</strong></p>
<p> </p>
<p><span style="font-size:24px;">4、代码实现</span></p>
<pre>
<code class="language-cs">void PwmInit(void)
{
//CH1:PA8 CH1N:PA7
/* GPIOA and GPIOB clock enable */
RCC_EnableAPB2PeriphClk(RCC_APB2_PERIPH_GPIOA| RCC_APB2_PERIPH_AFIO, ENABLE);
/* TIM1 clock enable */
RCC_EnableAPB2PeriphClk(RCC_APB2_PERIPH_TIM1, ENABLE);
GPIO_InitType GPIO_InitStructure;
GPIO_InitStruct(&GPIO_InitStructure);
/* GPIOA Configuration:TIM1 Channel1 as alternate function push-pull */
GPIO_InitStructure.Pin = GPIO_PIN_7 ;
GPIO_InitStructure.GPIO_Mode= GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Current = GPIO_DC_4mA;
GPIO_InitStructure.GPIO_Alternate = GPIO_AF5_TIM1;
GPIO_InitPeripheral(GPIOA, &GPIO_InitStructure);
GPIO_InitStructure.Pin = GPIO_PIN_8;
GPIO_InitStructure.GPIO_Alternate = GPIO_AF2_TIM1;
GPIO_InitPeripheral(GPIOA, &GPIO_InitStructure);
//108M
TIM_TimeBaseInitType TIM1_TimeBaseStructure;
TIM1_TimeBaseStructure.Period = 99; //999
TIM1_TimeBaseStructure.Prescaler = 107;
TIM1_TimeBaseStructure.ClkDiv = TIM_CLK_DIV1;
TIM1_TimeBaseStructure.CntMode = TIM_CNT_MODE_UP;
TIM_InitTimeBase(TIM1, &TIM1_TimeBaseStructure);
TIM_Enable(TIM1, ENABLE);
OCInitType TIM_OCInitStructure;
/* PWM1 Mode configuration: Channel1 */
TIM_OCInitStructure.OcMode = TIM_OCMODE_PWM2;
TIM_OCInitStructure.Pulse = 49;//499
TIM_OCInitStructure.OutputState = TIM_OUTPUT_STATE_ENABLE;
TIM_OCInitStructure.OcIdleState = TIM_OC_IDLE_STATE_RESET;
TIM_OCInitStructure.OcPolarity= TIM_OC_POLARITY_HIGH;
TIM_OCInitStructure.OutputNState= TIM_OUTPUT_NSTATE_ENABLE;
TIM_OCInitStructure.OcNIdleState= TIM_OCN_IDLE_STATE_SET;
TIM_OCInitStructure.OcNPolarity = TIM_OCN_POLARITY_HIGH;
TIM_InitOc1(TIM1, &TIM_OCInitStructure);
TIM_ConfigOc1Preload(TIM1, TIM_OC_PRE_LOAD_ENABLE);
TIM_EnableCtrlPwmOutputs(TIM1, ENABLE);
TIM_BDTRInitType TIM_BDTRInitStruct;
TIM_BDTRInitStruct.OssrState=TIM_OSSR_STATE_ENABLE;
TIM_BDTRInitStruct.OssiState=TIM_OSSI_STATE_ENABLE;
TIM_BDTRInitStruct.LockLevel=TIM_LOCK_LEVEL_OFF;
TIM_BDTRInitStruct.DeadTime =0xff; //9us
TIM_BDTRInitStruct.Break=TIM_BREAK_IN_DISABLE;
TIM_BDTRInitStruct.BreakPolarity=TIM_BREAK_POLARITY_HIGH;
TIM_BDTRInitStruct.AutomaticOutput=TIM_AUTO_OUTPUT_ENABLE;
TIM_ConfigBkdt(TIM1, &TIM_BDTRInitStruct);
}</code></pre>
<p> </p>
<p><span style="font-size:24px;">5、示波器观察现象</span></p>
<p><br />
</p>
<p>可以看出PWM互补输出、死区时间与程序中设置的一样。</p>
<p> </p>
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