Question
ADC RESOLUTION 8bit returning 12bit values after switching channels
#include "main.h"
#define ADC_BUF_LEN 9000
uint8_t adc_buf[ADC_BUF_LEN];
uint8_t ch = 0;
ADC_HandleTypeDef hadc;
DMA_HandleTypeDef hdma_adc;
TIM_HandleTypeDef htim2;
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_DMA_Init(void);
static void MX_ADC_Init(void);
static void MX_TIM2_Init(void);
/* USER CODE BEGIN PFP */
static void ADC_Select_CH0 (void);
static void ADC_Select_CH4 (void);
int main(void)
{
HAL_Init();
SystemClock_Config();
MX_GPIO_Init();
MX_DMA_Init();
MX_ADC_Init();
MX_TIM2_Init();
/* USER CODE BEGIN 2 */
HAL_ADC_Start_DMA(&hadc, (uint32_t*)adc_buf, ADC_BUF_LEN);
// start pwm generation
if(HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_4) != HAL_OK)
Error_Handler();
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
}
static void MX_ADC_Init(void)
{
hadc.Instance = ADC1;
hadc.Init.OversamplingMode = DISABLE;
hadc.Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV2;
hadc.Init.Resolution = ADC_RESOLUTION_8B;
hadc.Init.SamplingTime = ADC_SAMPLETIME_1CYCLE_5;
hadc.Init.ScanConvMode = ADC_SCAN_DIRECTION_FORWARD;
hadc.Init.DataAlign = ADC_DATAALIGN_RIGHT;
hadc.Init.ContinuousConvMode = DISABLE;
hadc.Init.DiscontinuousConvMode = ENABLE;
hadc.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_RISING;
hadc.Init.ExternalTrigConv = ADC_EXTERNALTRIGCONV_T2_TRGO;
hadc.Init.DMAContinuousRequests = ENABLE;
hadc.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
hadc.Init.Overrun = ADC_OVR_DATA_PRESERVED;
hadc.Init.LowPowerAutoWait = DISABLE;
hadc.Init.LowPowerFrequencyMode = DISABLE;
hadc.Init.LowPowerAutoPowerOff = DISABLE;
if (HAL_ADC_Init(&hadc) != HAL_OK)
{
Error_Handler();
}
ADC_ChannelConfTypeDef sConfig = {0};
sConfig.Channel = ADC_CHANNEL_0;
sConfig.Rank = ADC_RANK_CHANNEL_NUMBER;
if (HAL_ADC_ConfigChannel(&hadc, &sConfig) != HAL_OK)
{
Error_Handler();
}
}
/**
* @brief TIM2 Initialization Function
* @param None
* @retval None
*/
static void MX_TIM2_Init(void)
{
/* USER CODE BEGIN TIM2_Init 0 */
/* USER CODE END TIM2_Init 0 */
TIM_MasterConfigTypeDef sMasterConfig = {0};
TIM_OC_InitTypeDef sConfigOC = {0};
/* USER CODE BEGIN TIM2_Init 1 */
/* USER CODE END TIM2_Init 1 */
htim2.Instance = TIM2;
htim2.Init.Prescaler = 0;
htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
htim2.Init.Period = 4000;
htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim2.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
if (HAL_TIM_PWM_Init(&htim2) != HAL_OK)
{
Error_Handler();
}
sMasterConfig.MasterOutputTrigger = TIM_TRGO_UPDATE;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
if (HAL_TIMEx_MasterConfigSynchronization(&htim2, &sMasterConfig) != HAL_OK)
{
Error_Handler();
}
sConfigOC.OCMode = TIM_OCMODE_PWM1;
sConfigOC.Pulse = 0;
sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
if (HAL_TIM_PWM_ConfigChannel(&htim2, &sConfigOC, TIM_CHANNEL_4) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN TIM2_Init 2 */
/* USER CODE END TIM2_Init 2 */
}
/**
* Enable DMA controller clock
*/
static void MX_DMA_Init(void)
{
/* DMA controller clock enable */
__HAL_RCC_DMA1_CLK_ENABLE();
/* DMA interrupt init */
/* DMA1_Channel1_IRQn interrupt configuration */
HAL_NVIC_SetPriority(DMA1_Channel1_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(DMA1_Channel1_IRQn);
}
void ADC_Select_CH0 (void)
{
ch =0;
ADC_ChannelConfTypeDef sConfig = {0};
sConfig.Channel = ADC_CHANNEL_0;
sConfig.Rank = ADC_RANK_CHANNEL_NUMBER;
if (HAL_ADC_ConfigChannel(&hadc, &sConfig) != HAL_OK)
{
Error_Handler();
}
sConfig.Channel = ADC_CHANNEL_4;
sConfig.Rank = ADC_RANK_NONE;
if (HAL_ADC_ConfigChannel(&hadc, &sConfig) != HAL_OK)
{
Error_Handler();
}
if(HAL_ADCEx_Calibration_Start(&hadc, ADC_SINGLE_ENDED) != HAL_OK)
Error_Handler();
}
void ADC_Select_CH4 (void)
{
ch =4;
ADC_ChannelConfTypeDef sConfig = {0};
sConfig.Channel = ADC_CHANNEL_0;
sConfig.Rank = ADC_RANK_NONE;
if (HAL_ADC_ConfigChannel(&hadc, &sConfig) != HAL_OK)
{
Error_Handler();
}
sConfig.Channel = ADC_CHANNEL_4;
sConfig.Rank = ADC_RANK_CHANNEL_NUMBER;
if (HAL_ADC_ConfigChannel(&hadc, &sConfig) != HAL_OK)
{
Error_Handler();
}
if(HAL_ADCEx_Calibration_Start(&hadc, ADC_SINGLE_ENDED) != HAL_OK)
Error_Handler();
}
void HAL_ADC_ConvHalfCpltCallback (ADC_HandleTypeDef * hadc){
}
void HAL_ADC_ConvCpltCallback (ADC_HandleTypeDef * hadc)
{
HAL_ADC_Stop_DMA(hadc);
// start pwm generation
if(HAL_TIM_PWM_Stop(&htim2, TIM_CHANNEL_4) != HAL_OK)
Error_Handler();
uint16_t min = 4000;
uint16_t max = 0;
for (uint16_t i =0;i<1000;i++)
{
if (adc_buf[i] > max)
{
max = adc_buf[i];
}
else if (adc_buf[i] < min)
{
min = adc_buf[i];
}
}
if(max - min < 20 & ch == 0){ //320 20
ADC_Select_CH4();
}
else if(max - min > 237 & ch == 4){ //3800 237
ADC_Select_CH0();
}
else{
HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_14);
}
HAL_ADC_Start_DMA(hadc, (uint32_t*)adc_buf, ADC_BUF_LEN);
if(HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_4) != HAL_OK)
Error_Handler();
}Board: B-L072Z-LRWAN ( STM32L072CZY)
I am trying to record audio at 8kHz with 8 bits (using DMA and timer2)
I use 2 amplifiers with different amplification connected too PA0 and PA4
PA4 (amplification 10x of PA0)
I am trying to set my ADC to sample channel 0 and if that value is to small switch to channel 4
The values i get from this code are incorrect, for debugging i tried setting the DMA to HALFWORD and the buffer to uint16_t and the values the ADC returned after switching ones to channel 4 became 12bit resolution