Overview

This chapter uses an analog-to-digital converter (ADC) to sample multiple ADC channel voltages in a polling manner.

DMA sampling has been done before, please see:

https://blog.csdn.net/qq_24312945/article/details/106557538

Hardware Preparation

First you need to prepare a development board. Here I prepare the NUCLEO-F030R8 development board:

Select chip model

Use STM32CUBEMX to select the chip stm32f030r8 as follows:

Configuring the Clock Source

HSE and LSE are external high-speed clock and low-speed clock respectively. In this article, the built-in clock source is used, so the Disable option is selected for both, as shown below:

Configuring the Clock Tree

The maximum main frequency of STM32F0 is 48M, so configure 48:

Serial port configuration

This experiment uses serial port 1 for serial communication, and the baud rate is configured to 115200.

ADC Configuration

In STM32f030, there is an ADC (Analog/Digital Converter), each ADC has 12-bit, 10-bit, 8-bit and 6-bit options, and each ADC has 16 external channels, 2 internal channels and one VBAT channel signal.

This article will open three channels of ADC, IN0, IN1, and IN15, to read ADC respectively. Since serial port 2 is multiplexed with IN2 and IN3, IN2 and IN3 are not used. The configuration is as follows:

Generate project settings

Please note that Chinese characters cannot appear in the production project settings, otherwise an error will be reported.

Generate code

Configure Keil

Code

In main.c, add the header file. If you do not add it, an error message "identifier "FILE" is undefined" will appear.

/* USER CODE BEGIN Includes */

#include "stdio.h"

/* USER CODE END Includes */

Function declaration and serial port redirection:

/* USER CODE BEGIN PTD */

#ifdef __GNUC__

#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)

#else

#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)

#endif /* __GNUC__ */

PUTCHAR_PROTOTYPE

{

HAL_UART_Transmit(&huart1 , (uint8_t *)&ch, 1, 0xFFFF);

return ch;

}

/* USER CODE END PTD */

Variable definition:

/* USER CODE BEGIN 0 */

uint8_t in;

uint16_t adcBuf[3]; //Store ADC

/* USER CODE END 0 */

Main loop:

copy

/* USER CODE BEGIN WHILE */

while (1)

{

/* USER CODE END WHILE */

/* USER CODE BEGIN 3 */

i=0;

while(i<3)

{

HAL_ADC_Start(&hadc);//Start ADC

HAL_ADC_PollForConversion(&hadc,0xffff);//Wait for the conversion to complete. The second parameter indicates the timeout in ms.

//HAL_ADC_GetState(&hadc1) is used to obtain the ADC status. HAL_ADC_STATE_REG_EOC indicates that the conversion is complete and the conversion data is available.

if(HAL_IS_BIT_SET(HAL_ADC_GetState(&hadc),HAL_ADC_STATE_REG_EOC))//It is to determine whether the conversion completion flag is set. HAL_ADC_STATE_REG_EOC indicates the conversion completion flag. The conversion data is available

{

//Read ADC conversion data, the data is 12 bits. According to the data sheet, the register stores conversion data in 16 bits, and the data is right-aligned, so the conversion data range is 0~2^12-1, that is, 0~4095.

adcBuf [ i ] = HAL_ADC_GetValue ( & hadc ) ;

printf("

adc%d=%4.0d,voltage=%1.4f",i,adcBuf[i],adcBuf[i]*3.3f/4096);

i++;

}

}

HAL_ADC_Stop(&hadc);

HAL_Delay(500);

}

/* USER CODE END 3 */

Demonstration effect

Set adc0 port to 3.3V, adc1 port to GND, adc15 port to 1.5V, the output is as follows.