I have designed an L476 into a simple controller (BMS) and am trying to use the opamp and ADC and comparators to read the current, and implement a hardware fast overcurrent protection.
The opamp is working fine in PGA mode G16. I can see as I inject 20A across the current sensors, the stm pin goes up and down in voltage on my oscilloscope.
The ADC is set up in scan mode, with 14 conversions, and the rest of the channels read fine; I am reading lots of thermistors and input/output voltages and such like.
The opamp channel is simply returning noise between 475 and 493 counts irrespective of the current I inject (20A injected results in about 100mV shift in the opamp signal)
I have replicated this on a very simple sketch:
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_ADC1_Init();
MX_OPAMP2_Init();
MX_TIM3_Init();
/* USER CODE BEGIN 2 */
HAL_OPAMP_Start(&hopamp2);
HAL_ADCEx_Calibration_Start(&hadc1, ADC_SINGLE_ENDED);
HAL_Delay(100);
HAL_TIM_PWM_Start(&htim3, TIM_CHANNEL_1);
htim3.Instance->CCR1 = 100;
HAL_ADC_Start(&hadc1);
I have configured the opamp and timer and ADC as such:
static void MX_ADC1_Init(void)
{
/* USER CODE BEGIN ADC1_Init 0 */
/* USER CODE END ADC1_Init 0 */
ADC_MultiModeTypeDef multimode = {0};
ADC_ChannelConfTypeDef sConfig = {0};
/* USER CODE BEGIN ADC1_Init 1 */
/* USER CODE END ADC1_Init 1 */
/** Common config
*/
hadc1.Instance = ADC1;
hadc1.Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV1;
hadc1.Init.Resolution = ADC_RESOLUTION_12B;
hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
hadc1.Init.ScanConvMode = ADC_SCAN_DISABLE;
hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
hadc1.Init.LowPowerAutoWait = DISABLE;
hadc1.Init.ContinuousConvMode = DISABLE;
hadc1.Init.NbrOfConversion = 1;
hadc1.Init.DiscontinuousConvMode = DISABLE;
hadc1.Init.ExternalTrigConv = ADC_EXTERNALTRIG_T3_TRGO;
hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_RISING;
hadc1.Init.DMAContinuousRequests = DISABLE;
hadc1.Init.Overrun = ADC_OVR_DATA_OVERWRITTEN;
hadc1.Init.OversamplingMode = DISABLE;
if (HAL_ADC_Init(&hadc1) != HAL_OK)
{
Error_Handler();
}
/** Configure the ADC multi-mode
*/
multimode.Mode = ADC_MODE_INDEPENDENT;
if (HAL_ADCEx_MultiModeConfigChannel(&hadc1, &multimode) != HAL_OK)
{
Error_Handler();
}
/** Configure Regular Channel
*/
sConfig.Channel = ADC_CHANNEL_15;
sConfig.Rank = ADC_REGULAR_RANK_1;
sConfig.SamplingTime = ADC_SAMPLETIME_247CYCLES_5;
sConfig.SingleDiff = ADC_SINGLE_ENDED;
sConfig.OffsetNumber = ADC_OFFSET_NONE;
sConfig.Offset = 0;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN ADC1_Init 2 */
/* USER CODE END ADC1_Init 2 */
}
/**
* @brief OPAMP2 Initialization Function
* @PAram None
* @retval None
*/
static void MX_OPAMP2_Init(void)
{
/* USER CODE BEGIN OPAMP2_Init 0 */
/* USER CODE END OPAMP2_Init 0 */
/* USER CODE BEGIN OPAMP2_Init 1 */
/* USER CODE END OPAMP2_Init 1 */
hopamp2.Instance = OPAMP2;
hopamp2.Init.PowerSupplyRange = OPAMP_POWERSUPPLY_LOW;
hopamp2.Init.Mode = OPAMP_PGA_MODE;
hopamp2.Init.NonInvertingInput = OPAMP_NONINVERTINGINPUT_IO0;
hopamp2.Init.InvertingInput = OPAMP_INVERTINGINPUT_IO0;
hopamp2.Init.PgaGain = OPAMP_PGA_GAIN_16;
hopamp2.Init.PowerMode = OPAMP_POWERMODE_NORMALPOWER;
hopamp2.Init.UserTrimming = OPAMP_TRIMMING_FACTORY;
if (HAL_OPAMP_Init(&hopamp2) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN OPAMP2_Init 2 */
/* USER CODE END OPAMP2_Init 2 */
}
/**
* @brief TIM3 Initialization Function
* @PAram None
* @retval None
*/
static void MX_TIM3_Init(void)
{
/* USER CODE BEGIN TIM3_Init 0 */
/* USER CODE END TIM3_Init 0 */
TIM_MasterConfigTypeDef sMasterConfig = {0};
TIM_OC_InitTypeDef sConfigOC = {0};
/* USER CODE BEGIN TIM3_Init 1 */
/* USER CODE END TIM3_Init 1 */
htim3.Instance = TIM3;
htim3.Init.Prescaler = 47;
htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
htim3.Init.Period = 1000;
htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim3.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
if (HAL_TIM_PWM_Init(&htim3) != HAL_OK)
{
Error_Handler();
}
sMasterConfig.MasterOutputTrigger = TIM_TRGO_OC1REF;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
if (HAL_TIMEx_MasterConfigSynchronization(&htim3, &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(&htim3, &sConfigOC, TIM_CHANNEL_1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN TIM3_Init 2 */
/* USER CODE END TIM3_Init 2 */
}
I have noticed that if I alter the trigger frequency (set PSC to 470 or ARR to 10000) on the timer, that the value changes - it goes down to 380, or 120 if I increase both ARR and PSC - but still does not respond to current and does not affect the opamp output visibly for any value.
The GPIO is configured as such, looking at the registers:
And the ADC (DR is 7B/123 because right now the triggers are slow):
Ok, so... What am I getting wrong? Why does it not read the opamp? Any more info required I shall grab it!
Thanks!
