Posted on September 18, 2013 at 00:22Hi all,
I'm working on STM32L-discovery board and currently I'm trying to configure two analog outputs with DAC. I am able to see the result from the output pin but there seems to be some bias from the zero reference voltage. (Say, when I set the digital value to zero, the analog output is 90 mV) How should I modify my code to get the value zero? The following is my configuration:
void AO_Config()
{
GPIO_InitTypeDef GPIO_InitStructure;
DAC_InitTypeDef DAC_InitStructure;
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4 | GPIO_Pin_5;
GPIO_InitStructure.GPIO_
Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_
PuPd = GPIO_PuPd_NOPULL;
GPI
O_
Init(GPIOA,&GPIO_
InitStructure
);
DAC_DeInit();
DAC_InitStructure.DAC_Trigger = DAC_Trigger_None;
DAC_InitStructure.DAC_WaveGeneration = DAC_WaveGeneration_None;
DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Enable;
DAC_Init(DAC_Channel_2, &DAC_InitStructure);
DAC_Cmd(DAC_Channel_
2
,ENABLE);
DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Enable;
DAC_Init(DAC_Channel_1, &DAC_InitStructure);
DAC_Cmd(DAC_Channel_
1
,ENABLE);
DAC_SetChannel1Data(DAC_Align_12b_R, 0x0000);
DAC_SetChannel2Data(DAC_Align_12b_R, 0x0000);
}
[edit]
When I used the scope to monitor the pin, the result is as the following:
PA4: 0.558V@0, 2.312V@4095
PA5: 0.002V@0, 2.909V@4095
The range of PA4 becomes smaller? Don't really know why is that...
Thanks a lot!
#discovery #dac #stm32l
