基于ARM DSP库的OLED音乐频谱

arm_status arm_cfft_radix4_init_q15(arm_cfft_radix4_instance_q15 * S, uint16_t fftLen, uint8_t ifftFlag, uint8_t bitReverseFlag);
void arm_cfft_radix4_q15(const arm_cfft_radix4_instance_q15 * S, q15_t * pSrc);

arm_cfft_radix4_instance_q15 scfft;//创建整型复数基4fft实例
arm_cfft_radix4_init_q15(&scfft,FFT_LEN,0,1);//正变换 结果不翻转
arm_cfft_radix4_q15(&scfft,FFT_Buf);//FFT转换

void ADC_Config(void)
{
   GPIO_InitTypeDef GPIO_InitStructure;
   ADC_InitTypeDef ADC_InitStructure;
   TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
   RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
   RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1 | RCC_APB2Periph_GPIOA, ENABLE);
   
   RCC_ADCCLKConfig(RCC_PCLK2_Div4);//设置ADC分频系数
   
   TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);
   TIM_TimeBaseStructure.TIM_Prescaler = 0;
   TIM_TimeBaseStructure.TIM_Period = SystemCoreClock/(FFT_FREQ_THRESHOLD*2);//采样频率为最高频率的2倍
   TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
   TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
   TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
   TIM_ARRPreloadConfig(TIM3, ENABLE);
   TIM_SelectOutputTrigger(TIM3, TIM_TRGOSource_Update);//选择TIM3的UPDATE事件更新为触发源
   
   TIM_Cmd(TIM3, ENABLE);
   
   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;
   GPIO_Init(GPIOA, &GPIO_InitStructure);//将PA1配置为模拟输入模式
   
   ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;//独立模式
   ADC_InitStructure.ADC_ScanConvMode = DISABLE;//关闭自动扫描转换
   ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;//关闭连续转换
   ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T3_TRGO;//使用TIM3作为转换触发源
   ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;//数据右对齐
   ADC_InitStructure.ADC_NbrOfChannel = 1;//共使用1个通道
   ADC_Init(ADC1, &ADC_InitStructure);
   ADC_RegularChannelConfig(ADC1, ADC_Channel_1, 1, ADC_SampleTime_55Cycles5);//设置ADC1的常规转换通道为通道1
   ADC_DMACmd(ADC1, ENABLE);//使能ADC1的DMA请求
   ADC_Cmd(ADC1, ENABLE);//启动ADC1
   ADC_ResetCalibration(ADC1);
   while(ADC_GetResetCalibrationStatus(ADC1));//禁止ADC1的校准功能
   ADC_StartCalibration(ADC1);
   while(ADC_GetCalibrationStatus(ADC1));//启动ADC1的校准功能
   ADC_SoftwareStartConvCmd(ADC1, ENABLE);//启动ADC1的软件触发转换
}
void DMA_Config(void)
{
   DMA_InitTypeDef DMA_InitStructure;
   NVIC_InitTypeDef NVIC_InitStructure;
   
   RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);
   
   DMA_DeInit(DMA1_Channel1);
   DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)0x4001244C;//ADC1->DR
   DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)ADC_Buf;
   DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
   DMA_InitStructure.DMA_BufferSize = FFT_LEN;//数据长度
   DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
   DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
   DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
   DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;//数据长度16位
   DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;//单次转换模式
   DMA_InitStructure.DMA_Priority = DMA_Priority_High;
   DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
   DMA_Init(DMA1_Channel1, &DMA_InitStructure);
   DMA_ITConfig(DMA1_Channel1, DMA_IT_TC, ENABLE);//传输完成中断
   
   DMA_Cmd(DMA1_Channel1, ENABLE);//开启DMA1通道1
   
   NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel1_IRQn;//DMA1_Stream1
   NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;//抢占优先级0
   NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
   NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
   NVIC_Init(&NVIC_InitStructure);
}
void DMA1_Channel1_IRQHandler(void)
{
   if(DMA_GetFlagStatus(DMA1_FLAG_TC1))//传输完成中断
   {
      ADC_ConvFlag = 1;
      
      DMA_ClearITPendingBit(DMA_IT_TC);
   }
}

int main(void)
{
   uint16_t i;
   arm_cfft_radix4_instance_q15 scfft;//创建整型复数基4fft实例
   
   delay_init();
   arm_cfft_radix4_init_q15(&scfft,FFT_LEN,0,1);//正变换 结果不翻转
   
   OLED_Init();
   ADC_Config();
   
   while(1)
   {
      while(ADC_ConvFlag == 0);//等待转换完成
      ADC_ConvFlag = 0;
      
      for(i = 0;i < FFT_LEN;i ++)
      {
         FFT_Buf[i*2] = ADC_Buf[i];
         FFT_Buf[i*2+1] = 0;
      }
      //此时转换完成的数据已经从ADC缓冲区复制到FFT缓冲区 可以进行新的转换
      DMA_Config();//初始化DMA并启动新的一次转换
      
      arm_cfft_radix4_q15(&scfft,FFT_Buf);//FFT转换
      fft_show();
   }
}

void fft_show(void)
{
   uint16_t i, temp;
   uint8_t col_temp;
   
   for(i = 0;i < OLED_X;i ++)
   {
      FFT_Buf[i] = sqrt(FFT_Buf[2*i]*FFT_Buf[2*i] + FFT_Buf[2*i+1]*FFT_Buf[2*i+1]);//取复数的模
      //结束后FFT结果只剩下前半部分为模值
      if(FFT_Buf[i] > 63)//限幅
         FFT_Buf[i] = 63;
   }
   FFT_Buf[0] = 0;//去掉直流分量
   
   for(i = 0;i < OLED_X*OLED_Y;i ++)//清空OLED刷新缓存
   {
      OLED_VRAM[i] = 0;
   }
   
   for(i = 0;i < OLED_X;i ++)
   {
      col_temp = 7;
      temp = FFT_Buf[i];
      
      while(temp > 8)
      {
         OLED_VRAM[col_temp*OLED_X+i] = 0xFF;//先画整个字节的
         col_temp --;
         temp -= 8;
      }
      OLED_VRAM[col_temp*OLED_X+i] = 0xFF << (8-temp);//画最后的不足一个字节的
   }
   
   OLED_bmp(0,0,OLED_X,OLED_Y,OLED_VRAM);//将缓存刷新到屏幕上
}