hello, i am working with a stm32f407 discovery and a current sensor acs712 / 20A , the adc of the card hold input from 0 to 3.3v and the sensor presents an output from 0 to 5v so i have added a voltage divider with two resistors of 2.2k and 3.3k, when measuring what the sensor delivers to current 0, this delivers a voltage of approximately 1. 5v (measured with multimeter), but the adc delivers a conversion with too much noise, not equivalent with the sensor datasheet, I have 4 of these sensors and I test with all of them to make sure that this was not the problem, I am making the measurement continuously and I have tried with several adc configurations, I am not an expert in the subject of sensors so I do not know the type of treatment I should give to the input signal to obtain reliable values (since the measurement errors in the ADC present variations of up to +-50) or if the problem is with the configuration of the ADC. i leave the typical adc configuration that i have been using and i hope someone can help me with this issue. Greetings.
static void MX_ADC1_Init(void)
{
ADC_ChannelConfTypeDef sConfig = {0};
/** Configure the global features of the ADC (Clock, Resolution, Data Alignment and number of conversion)
*/
hadc1.Instance = ADC1;
hadc1.Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV8;
hadc1.Init.Resolution = ADC_RESOLUTION_10B;
hadc1.Init.ScanConvMode = DISABLE;
hadc1.Init.ContinuousConvMode = ENABLE;
hadc1.Init.DiscontinuousConvMode = DISABLE;
hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
hadc1.Init.NbrOfConversion = 1;
hadc1.Init.DMAContinuousRequests = DISABLE;
hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
if (HAL_ADC_Init(&hadc1) != HAL_OK)
{
Error_Handler();
}
/** Configure for the selected ADC regular channel its corresponding rank in the sequencer and its sample time.
*/
sConfig.Channel = ADC_CHANNEL_1;
sConfig.Rank = 1;
sConfig.SamplingTime = ADC_SAMPLETIME_480CYCLES;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
{
Error_Handler();
}
}
