Not able to get required samples from ADC DMA triggered using timer [STM32F103C8]

[x4ce]

Hello,

I am acquiring samples from 50Hz Sine Wave through a CT and want to get 100 samples of this signal (T=20ms). For this, I need each sample at 200us apart so I get an array of 100 bytes. I have following clock setup:

APB1 = 36Mhz; ADC = 12Mhz

TIM3 Event: 36,000,000/ 7,200 = 5,000Hz = 200us

ADC Sample Time: Sampling Time + 12.5 cycles = 239.5 + 12.5 = 252 cycles => 1/12Mhz X 252 = 21us

TIM3:

ADC:

Using above settings & calculations, SOC is supposed to complete said ADC in 21us and sample time is 200us which is fine. Here is the code:

/* USER CODE BEGIN PV */
uint16_t adc_value[500] = {0};
/* USER CODE END PV */

  /* USER CODE BEGIN 2 */
  HAL_TIM_Base_Start(&htim3);
  HAL_ADCEx_Calibration_Start(&hadc1);
  HAL_ADC_Start_DMA(&hadc1, (uint32_t *)adc_value, sizeof(adc_value));
  /* USER CODE END 2 */

/* ADC Config */
hadc1.Instance = ADC1;
  hadc1.Init.ScanConvMode = ADC_SCAN_DISABLE;
  hadc1.Init.ContinuousConvMode = DISABLE;
  hadc1.Init.DiscontinuousConvMode = DISABLE;
  hadc1.Init.ExternalTrigConv = ADC_EXTERNALTRIGCONV_T3_TRGO;
  hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
  hadc1.Init.NbrOfConversion = 1;

sConfig.Channel = ADC_CHANNEL_5;
  sConfig.Rank = ADC_REGULAR_RANK_1;
  sConfig.SamplingTime = ADC_SAMPLETIME_239CYCLES_5;
/* ADC Config */

/* TIM3 Config */
  htim3.Instance = TIM3;
  htim3.Init.Prescaler = 0;
  htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim3.Init.Period = 7200;
  htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim3.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
/* TIM3 Config */

I am getting samples in the 400 byte array but I am supposed to get a complete sine wave cycle in first 100 byte but the cycle is completed in 200 bytes. Even I tried to increased sampling time (Counter Period: 14,400) it shows same the result. Here is the samples vs. data result:

Please guide, what I may be missing in the code or in calculations to get a complete 50Hz Sine Wave cycle in ADC of 100 samples.

Regards

Shahid