原理:
- 當計數值向上溢出或者向下溢出時,對應增加和減少重裝載的值 0xFFFF。
- 對此讀取 (TIM1->CNT + abs_count)是爲了防止中途被中斷打斷而破壞組包數據。不建議屏蔽中斷去讀取,查詢過快時也會造成中斷開啓關閉過快,會造成系統實時性下降。
static int abs_count = 0;//絕對位置
void Speed_ENC(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOE, ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_11;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOE, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOE, GPIO_PinSource9, GPIO_AF_TIM1);
GPIO_PinAFConfig(GPIOE, GPIO_PinSource11, GPIO_AF_TIM1);
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseStructure.TIM_Period = 0xFFFF;
TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);
TIM_EncoderInterfaceConfig(TIM1, TIM_EncoderMode_TI12, TIM_ICPolarity_Rising, TIM_ICPolarity_Rising);
TIM_Cmd(TIM1, ENABLE);
NVIC_InitStructure.NVIC_IRQChannel = TIM1_UP_TIM10_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
TIM_ClearITPendingBit(TIM1, TIM_IT_Update);
TIM_ITConfig(TIM1, TIM_IT_Update, ENABLE);
}
void TIM1_UP_TIM10_IRQHandler(void)
{
if (TIM_GetITStatus(TIM1, TIM_IT_Update) != RESET) //溢出
{
if (TIM1->CR1 & (1 << 4))
abs_count -= 0xFFFF;
else
abs_count += 0xFFFF;
TIM_ClearITPendingBit(TIM1, TIM_IT_Update);
}
}
//***************設置當前絕對位置**************
void TIM1_Encoder_Write(int data)
{
TIM_ITConfig(TIM1, TIM_IT_Update, DISABLE);
TIM1->CNT = 0;
abs_count = data;
TIM_ClearITPendingBit(TIM1, TIM_IT_Update);
TIM_ITConfig(TIM1, TIM_IT_Update, ENABLE);
}
//*************讀計當前絕對位置**************
int TIM1_Encoder_Read(void)
{
int cnt1 = TIM1->CNT + abs_count;
int cnt2 = TIM1->CNT + abs_count;
if (cnt1 == cnt2)
return cnt1; //未出現中斷
else
return TIM1->CNT + abs_count; //可能剛發生中斷
}