Posted on October 18, 2013 at 01:54Hi all,
I have two questions about DAC configuration.
1. The below cofiguration code works for two analog outputs. I can write my values to PA4 and PA5 by:
DAC_SetChannel1Data(DAC_Align_12b_R, 0x0000); // PA4
DAC_SetChannel2Data(DAC_Align_12b_R, 0x0000); // PA5
But I wonder which part of the code links PA4 pin with DAC_channel1 and PA5 with DAC_channel2 together respectively?
void AnalogOutput_Config(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
DAC_InitTypeDef DAC_InitStructure;
/* GPIOA clock enable */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
/* DAC Periph clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);
/*------------------------ GPIO configuration ------------------------*/
/* Configure PA4 and PA5 as analog output */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4 | GPIO_Pin_5;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_40MHz;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* -------------------------- DAC_Channel2 Configuration --------------------*/
DAC_DeInit();
DAC_InitStructure.DAC_Trigger = DAC_Trigger_None;
DAC_InitStructure.DAC_WaveGeneration = DAC_WaveGeneration_None;
DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Disable;
/*DAC Channel2 Init */
DAC_Init(DAC_Channel_2, &DAC_InitStructure);
/*Enable DAC Channel2 */
DAC_Cmd(DAC_Channel_2, ENABLE);
/* -----------------------------DAC_Channel1 Configuration ------------------------*/
DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Disable;
/*DAC Channel1 Init */
DAC_Init(DAC_Channel_1, &DAC_InitStructure);
/*Enable DAC Channel1*/
DAC_Cmd(DAC_Channel_1, ENABLE);
/* set default analog output as zero */
DAC_SetChannel1Data(DAC_Align_12b_R, 0x0000); // PA4
DAC_SetChannel2Data(DAC_Align_12b_R, 0x0000); // PA5
}
2. If one DAC channel can only be used by one analog output, at most I can only have two analog outputs. (There are only 2 dac channels for stm32l-discovery) What can I do if I want to include more analog outputs?
Thanks a lot.
