Posted on March 12, 2018 at 16:31Hi,
I am having a problem using COMP1 on a STM32l496 chip. I am doing a proof of concept on a Nucleo board. I'm using a signal generator to put a 1KHz sine wave on the IN+ pin, and I'm using the DAC as the IN- signal, with the value set to 0. I'm using CubeMX to generate code for this. When I run this setup, I get no changes on the comparator. When I configure the project to use an external pin as IN-, and attach that pin to ground, I get the expected toggling output from the comparator. When I look at the DAC output, by configuring it's output to go to both an on-chip peripheral and external pin and looking at the pin, the output looks fine. Does anyone have any idea what I may be doing wrong? I'm including a code snippet of the COMP1 and DAC setup, and also the lines to show they are running.
// from main()
HAL_COMP_Start(&hcomp1);
HAL_DAC_Start(&hdac1, DAC_CHANNEL_2);
HAL_DAC_SetValue(&hdac1, DAC_CHANNEL_2, DAC_ALIGN_12B_R, 100);
/* COMP1 init function */
static void MX_COMP1_Init(void)
{
hcomp1.Instance = COMP1;
hcomp1.Init.InvertingInput = COMP_INPUT_MINUS_DAC1_CH2;
hcomp1.Init.NonInvertingInput = COMP_INPUT_PLUS_IO2;
hcomp1.Init.OutputPol = COMP_OUTPUTPOL_NONINVERTED;
hcomp1.Init.Hysteresis = COMP_HYSTERESIS_NONE;
hcomp1.Init.BlankingSrce = COMP_BLANKINGSRC_NONE;
hcomp1.Init.Mode = COMP_POWERMODE_HIGHSPEED;
hcomp1.Init.WindowMode = COMP_WINDOWMODE_DISABLE;
hcomp1.Init.TriggerMode = COMP_TRIGGERMODE_NONE;
if (HAL_COMP_Init(&hcomp1) != HAL_OK)
{
_Error_Handler(__FILE__, __LINE__);
}
}
/* DAC1 init function */
static void MX_DAC1_Init(void)
{
DAC_ChannelConfTypeDef sConfig;
/**DAC Initialization
*/
hdac1.Instance = DAC1;
if (HAL_DAC_Init(&hdac1) != HAL_OK)
{
_Error_Handler(__FILE__, __LINE__);
}
/**DAC channel OUT2 config
*/
sConfig.DAC_SampleAndHold = DAC_SAMPLEANDHOLD_DISABLE;
sConfig.DAC_Trigger = DAC_TRIGGER_NONE;
sConfig.DAC_OutputBuffer = DAC_OUTPUTBUFFER_ENABLE;
sConfig.DAC_ConnectOnChipPeripheral = DAC_CHIPCONNECT_ENABLE;
sConfig.DAC_UserTrimming = DAC_TRIMMING_FACTORY;
if (HAL_DAC_ConfigChannel(&hdac1, &sConfig, DAC_CHANNEL_2) != HAL_OK)
{
_Error_Handler(__FILE__, __LINE__);
}
}
Ricardo
