CH32 Oscillator

In order to get to know the CH32V307 MCU better I decided to create a dual oscillator using the DACs.

Timer

void Timer4_Init (void) {
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure = { 0 };
    RCC_APB1PeriphClockCmd (RCC_APB1Periph_TIM4, ENABLE);

    TIM_TimeBaseStructInit (&TIM_TimeBaseStructure);
    TIM_TimeBaseStructure.TIM_Period = 3000 - 1;
    TIM_TimeBaseStructure.TIM_Prescaler = 0;
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit (TIM4, &TIM_TimeBaseStructure);

    TIM_SelectOutputTrigger (TIM4, TIM_TRGOSource_Update);
    TIM_Cmd (TIM4, ENABLE);
}

DMA

void Dac_Dma_Init (void) {
    DMA_InitTypeDef DMA_InitStructure = { 0 };
    RCC_AHBPeriphClockCmd (RCC_AHBPeriph_DMA2, ENABLE);

    DMA_StructInit (&DMA_InitStructure);
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t) &(DAC->RD12BDHR);
    DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t) &dac_buffer[0];
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
    DMA_InitStructure.DMA_BufferSize = 2 * BUFFER_SIZE;
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
    DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Word;
    DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Word;
    DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
    DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh;
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

    DMA_Init (DMA2_Channel3, &DMA_InitStructure);

    DMA_ITConfig (DMA2_Channel3, DMA_IT_TC, ENABLE);
    DMA_ITConfig (DMA2_Channel3, DMA_IT_HT, ENABLE);

    DMA_Cmd (DMA2_Channel3, ENABLE);

}

DAC

void Dual_Dac_Init (void) {
    GPIO_InitTypeDef GPIO_InitStructure = { 0 };
    DAC_InitTypeDef DAC_InitType = { 0 };

    // Make sure the APB busses are clocked
    RCC_APB2PeriphClockCmd (RCC_APB2Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd (RCC_APB1Periph_DAC, ENABLE);

    // Configure PA4 and PA5 for analog output
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4 | GPIO_Pin_5;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init (GPIOA, &GPIO_InitStructure);
    GPIO_SetBits (GPIOA, GPIO_Pin_4);

    // Throw a debug pulse out on PA6
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_Init (GPIOA, &GPIO_InitStructure);

    // DAC convertion triggered by Timer 4
    DAC_InitType.DAC_Trigger = DAC_Trigger_T4_TRGO;
    DAC_InitType.DAC_WaveGeneration = DAC_WaveGeneration_None;
    DAC_InitType.DAC_LFSRUnmask_TriangleAmplitude = DAC_LFSRUnmask_Bit0;
    DAC_InitType.DAC_OutputBuffer = DAC_OutputBuffer_Enable;
    DAC_Init (DAC_Channel_1, &DAC_InitType);
    DAC_Init (DAC_Channel_2, &DAC_InitType);

    DAC_Cmd (DAC_Channel_1, ENABLE);
    DAC_Cmd (DAC_Channel_2, ENABLE);

    DAC_DMACmd (DAC_Channel_1, ENABLE);
    DAC_DMACmd (DAC_Channel_2, ENABLE);

    DAC_SetDualChannelData (DAC_Align_12b_R, 0x123, 0x321);
}

Miscellaneous Links

• Project on Github