Hands-On STM32CubeIDE project

[LauraCx]

ADC interleaved mode (2/2): Hands-On
STM32CubeIDE project

This series of articles will provide you with:

• Tips&tricks on how to implement ADC interleaved mode to double equivalent sampling rate
• ADC interleave mode details from practical point of view
• Info on DMA data transfer using ADC Common Data Register

First Part on the article is available here

1. New project creation

• Open STM32CubeIDE
• File → New STM32 project → select STM32L476RG
• Enter project name and location
• Press Finish button

2. System Core

File → New STM32 project → STM32L476RG (NUCLEO)
Pinout & Configuration tab → System Core → SYS
Select Debug interface: Serial Wire

3. Analog Settings

• Pinout & Configuration tab → Analog → ADC1

• Pinout & Configuration tab → Analog → ADC1 : ADC1 Parameters Settings tab:
  -Mode: Dual interleaved mode only
  -DMA Access Mode: DMA access mode enabled
  -Delay between 2 sampling phases: 3 Cycles
  -Synchronous clock mode divided by 1
  -Continuous Conversion Mode: Enabled
  -DMA Continuous Requests: Enabled
  -Rank 1; Channel: Channel 5, Sampling Time: 6.5 Cycles

• Pinout & Configuration tab → Analog → ADC1: Configure ADC1 in DMA Settings tab

- ADC1, DMA1 Channel 1, Peripheral To Memory, Low

- Mode: Normal,
- Increment Address: Memory,
- Data Width: Word

• Pinout & Configuration tab → Analog → ADC2 : Configure ADC2 in Parameters Settings tab

-Mode: Dual interleaved mode only

-DMA Access Mode: DMA access mode enabled

-Delay between 2 sampling phases: 3 Cycles

-Synchronous clock mode divided by 1

-Continuous Conversion Mode: Enabled

-Rank 1; Channel: Channel 5, Sampling Time: 6.5 Cycles

• Pinout & Configuration tab → Connectivity → USART2

USART2 Mode: Asynchronous
USART2 in Parameters Settings tab

-Baud Rate: 115200 Bits/s,

-Char Length: 8Bits,

-Parity: None,

-Stop Bits: 1

4. Clock Configuration tab

• Set HCLK frequency as 80MHz

5. Generate code

• Click on 
• Open C perspective and edit main.c file

6. Insert relevant code in main.c

• Follow user code section names, section by section and put relevant code of main.c

1. USER CODE Includes section

#include <stdio.h>

2. USER CODE PD

#define ADC_BUF_SIZE 20

3. USER CODE PV

static uint32_t adcBuf[ADC_BUF_SIZE];  
static uint32_t adcFlag = RESET;

4. USER CODE 0

int _write(int file, char *ptr, int len)
{
 HAL_UART_Transmit(&huart2,(uint8_t*)ptr,len,100);
  return len;
}

5. USER CODE 2

HAL_ADCEx_Calibration_Start(&hadc1,ADC_SINGLE_ENDED);
HAL_ADCEx_Calibration_Start(&hadc2,ADC_SINGLE_ENDED);

LL_ADC_SetMultiDMATransfer(ADC123_COMMON,LL_ADC_MULTI_REG_DMA_LIMIT_RES12_10B);  //One shot MDMA mode

HAL_ADCEx_MultiModeStart_DMA(&hadc1,adcBuf,ADC_BUF_SIZE);
__HAL_DMA_DISABLE_IT(&hdma_adc1,DMA_IT_HT);  //Avoid DMA half transfer interrupt trigger

7. MDMA mode

• MDMA=0b10: a single DMA request is generated each time both master and slave EOC events have occurred, 32-bit register ADCx_CDR contains the two half-words representing two ADC-converted data items (10 or 12 bit).

• Follow user code section names, section by section and put relevant code of main.c

6. USER CODE 3

if (adcFlag)
{
  printf("-------------\r\n");
  for(uint32_t i=0;i<ADC_BUF_SIZE;i++)
  {
    printf("%u\r\n",(uint16_t)(adcBuf[i]&0x0000FFFF));  //LSB -> MASTER
    printf("%u\r\n",(uint16_t)(adcBuf[i]>>16));         //MSB -> SLAVE
  }
  HAL_Delay(1000);

  adcFlag = RESET;
  HAL_ADCEx_MultiModeStart_DMA(&hadc1,adcBuf,ADC_BUF_SIZE);
  __HAL_DMA_DISABLE_IT(&hdma_adc1,DMA_IT_HT);
}

7. USER CODE 4

void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef *AdcHandle)
{
  adcFlag = SET;
}

8. Final steps

• 10. Start terminal: 115200,8,N,1 and observe ADC results, check if application is running

• 11. Connect signal generator: sinus 500kHz / 3Vpp, follow MCU electrical limits (unipolar voltage), pin 1 of CN8 or pin 28 of CN7

• 12. Observe the ADC results, import text data to Excel