Welcome to STM32-BoardCar repository

5. Voltage detection (ADC)

Voltage detection

Voltage detection1. Software-Hardware2. Brief principle1. Hardware schematic diagram2. Physical connection diagram3. Control principle3. Project configuration1. Description2. Pin configuration4. Main functions1. User function2. LL library function analysis5. Experimental phenomena

This tutorial demonstrates: obtaining the real-time voltage of the battery pack through ADC (ADC3_IN5), and printing the battery voltage information through serial port (UASRT1).

1. Software-Hardware

STM32F103CubeIDE
STM32 Robot Development Board
ADC, USART: chip internal peripherals
7.4V battery pack: external
Type-C data cable or ST-Link
Download programs or simulate the development board

2. Brief principle

1. Hardware schematic diagram

2. Physical connection diagram

When conducting this experiment, an external 7.4V battery pack is required.

3. Control principle

Obtain the converted value of the battery BAT pin through a single ADC, convert the value into actual voltage information and print it out through the serial port.

ADC

STM32F103ZET6 has three built-in 12-bit analog-to-digital converters. Each ADC controller has up to 18 channels and can measure 16 external and 2 internal signal sources.

ADC Channel
Only the ADC channels used in this tutorial are selected here.

ADC conversion value

The ADC of STM32F103ZET6 is a 12-bit successive approximation analog-to-digital converter with 12-bit resolution;

A D C v a l u e r a n g e = 0 - 2^{12} = 0 - 4095

The ADC converted value can be stored in the 16-bit data register in a left-justified or right-justified manner.

ADC Conversion Mode

A/D conversion of each channel of the ADC can be performed in single, continuous, scan or discontinuous modes.

model	function
Single conversion mode	ADC only performs one conversion
continuous conversion mode	As soon as the previous ADC conversion is completed, another conversion is started.
Scan mode	Used to scan a group of ADC channels
Intermittent mode	Group conversion of multiple ADC channels until the entire sequence is converted


Rule channel: perform channel conversion in a certain order
Injection channel: The injection channel can interrupt the conversion of the regular channel to execute the injection channel. After the injection channel is completed, the regular channel conversion can be continued.

ADC conversion time

The input clock of the ADC must not exceed 14MHz, which is generated by dividing PCLK2.

T o t a l c o n v e r s i o n t i m e = T_{C O N V} = s a m p l i n g t i m e + 12.5 c l o c k c y c l e s

Conversion time of this tutorial: ADC clock frequency 12MHz, sampling time 239.5 clock cycles

T o t a l c o n v e r s i o n t i m e = T_{C O N V} = s a m p l i n g t i m e + 12.5 c l o c k c y c l e s = (239.5 + 12.5) * \frac{1}{12000000} = 21 u s

Actual voltage conversion: ADC internal reference voltage 3.3V

V_{B A T} = \frac{V a l u e_{A D C c o n v e r t e d v a l u e} * (3.3)}{4096}

Referring to the hardware schematic diagram, we can see: Principle of equal current

I_{C u r r e n t} = \frac{V_{B A T}}{R 7} = \frac{V_{M}}{R 3 + R 7} ⟹ \frac{V_{B A T}}{3.3} = \frac{V_{M}}{10 + 3.3} ⟹ V_{M} = \frac{V_{B A T} * (10 + 3.3)}{3.3}

T h a t i s, a c t u a l v o l t a g e = V_{M} = \frac{V_{B A T} * (10 + 3.3)}{3.3}

3. Project configuration

Project configuration: Prompt configuration options during STM32CubeIDE project configuration

1. Description

Omitted project configuration part: New project, chip selection, project configuration, SYS of pin configuration, RCC configuration, clock configuration and project configuration content

The project configuration part that is not omitted is the key point that needs to be configured in this tutorial.


xxxxxxxxxx
Please refer to [2. Development environment construction and use: STM32CubeIDE installation and use] to understand how to configure the omitted parts of the project.

2. Pin configuration

Configure specified pin function

You can directly select the corresponding pin number in the pin view, and the corresponding options will appear when you left-click the mouse.

ADC

USART

Clock Configuration

Advanced Settings

Generate code

4. Main functions

It mainly introduces the functional code written by the user. For detailed code, you can open the project file provided by us yourself and enter the Bsp folder to view the source code.

1. User function

Function: Redirect print


x
#include "stdio.h"

#ifdef __GNUC__
  #define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
  #define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif

PUTCHAR_PROTOTYPE {
  HAL_UART_Transmit(&USART1, (uint8_t *)&ch, 1, 0xFFFF);
  return ch;
}

Function: Get_BAT

Function prototype	uint16_t Get_BAT(uint32_t ch)
Function description	Obtain battery ADC conversion raw data
Input parameters	ch: channel
Return value	ADC converted value

Function: Adc_Get_Average

Function prototype	uint16_t Adc_Get_Average(uint32_t ch, uint8_t times)
Function description	Average value of multiple ADC conversion values
Input parameter 1	ch: channel
Input parameter 2	times: average times
Return value	ADC converted value

Function: Adc_Get_Measure_Volotage

Function prototype	float Adc_Get_Measure_Volotage(void)
Function description	Get original voltage value
Input parameters	None
Return value	Original voltage value

Function: Adc_Get_Battery_Volotage

Function prototype	float Adc_Get_Battery_Volotage(void)
Function description	Obtain the actual battery voltage before voltage division
Input parameters	None
Return value	Actual battery voltage

2. LL library function analysis

The HAL library functions that have been introduced in the previous tutorial will not be introduced again in the tutorial!


xxxxxxxxxx
If you want to find the HAL library and LL library function analysis involved in the entire tutorial, you can view the documents in the folder [8. STM32 Manual: STM32F1_HAL Library and LL Library_User Manual]

Function: HAL_ADC_Init

Function prototype	HAL_StatusTypeDef HAL_ADC_Init(ADC_HandleTypeDef* hadc)
Function description	Initialize ADC parameters
Input parameters	hadc: ADC handle address
Return value	HAL status value: HAL_OK, HAL_ERROR, HAL_BUSY, HAL_TIMEOUT

Function: HAL_ADC_MspInit

Function prototype	void HAL_ADC_MspInit(ADC_HandleTypeDef* hadc)
Function description	Initialize the peripheral clock, GPIO and NVIC of the ADC
Input parameters	hadc: ADC handle address
Return value	None

Function: HAL_ADC_MspDeInit

Function prototype	void HAL_ADC_MspDeInit(ADC_HandleTypeDef* hadc)
Function description	Cancel the initialization of ADC peripheral clock, GPIO and NVIC
Input parameters	hadc: ADC handle address
Return value	None

Function: HAL_ADC_ConfigChannel

Function prototype	HAL_StatusTypeDef HAL_ADC_ConfigChannel (ADC_HandleTypeDef* hadc, ADC_ChannelConfTypeDef* sConfig)
Function description	Configure ADC specific channels
Input parameter 1	hadc: ADC handle address
Input parameter 2	sConfig: Configure ADC channel parameters: conversion channel, conversion sequence, sampling period
Return value	HAL status value: HAL_OK, HAL_ERROR, HAL_BUSY, HAL_TIMEOUT

Function: HAL_ADC_Start

Function prototype	HAL_StatusTypeDef HAL_ADC_Start(ADC_HandleTypeDef* hadc)
Function description	Enable ADC rule group conversion
Input parameters	hadc: ADC handle address
Return value	HAL status value: HAL_OK, HAL_ERROR, HAL_BUSY, HAL_TIMEOUT

Function: HAL_ADC_PollForConversion

Function prototype	HAL_StatusTypeDef HAL_ADC_PollForConversion(ADC_HandleTypeDef* hadc, uint32_t Timeout)
Function description	Wait for ADC rule group conversion to complete
Input parameter 1	hadc: ADC handle address
Input parameter 2	Timeout: timeout time
Return value	HAL status value: HAL_OK, HAL_ERROR, HAL_BUSY, HAL_TIMEOUT

Function: HAL_ADC_GetValue

Function prototype	uint32_t HAL_ADC_GetValue(ADC_HandleTypeDef* hadc)
Function description	Get ADC conversion value
Input parameters	hadc: ADC handle address
Return value	ADC conversion value

Function: HAL_UART_Init

Function prototype	HAL_StatusTypeDef HAL_UART_Init(UART_HandleTypeDef *huart)
Function description	Initialize serial port parameters
Input parameters	huart: serial port handle address
Return value	HAL status value: HAL_OK, HAL_ERROR, HAL_BUSY, HAL_TIMEOUT

Function: HAL_UART_MspInit

Function prototype	void HAL_UART_MspInit(UART_HandleTypeDef *huart)
Function description	Initialize the peripheral clock, GPIO and NVIC of the serial port
Input parameters	huart: serial port handle address
Return value	None

Function: HAL_UART_MspDeInit

Function prototype	void HAL_UART_MspInit(UART_HandleTypeDef *huart)
Function description	Cancel the initialization of serial port peripheral clock, GPIO and NVIC
Input parameters	huart: serial port handle address
Return value	None

Function: HAL_UART_Transmit

Function prototype	HAL_StatusTypeDef HAL_UART_Transmit (UART_HandleTypeDef huart, const* uint8_t *pData, uint16_t Size, uint32_t Timeout)
Function description	Send data in polling mode
Input parameter 1	huart: serial port handle address
Input parameter 2	pData: The first address of the data buffer to be sent
Input parameter 3	Size: Number of data bytes sent
Input parameter 4	Timeout: timeout time, in milliseconds
Return value	HAL status value: HAL_OK, HAL_ERROR, HAL_BUSY, HAL_TIMEOUT

5. Experimental phenomena

After successfully downloading the program, press the RESET button on the development board to open the serial port debugging assistant to observe the phenomenon!


xxxxxxxxxx
For program download, please refer to [2. Development environment construction and use: program download and simulation]

Phenomenon:

The serial port debugging assistant will print the real-time voltage information of the battery pack (the maximum voltage of the 7.4V battery pack can reach 8.4V).

Serial communication (UASRT)

Internal temperature sensor（ADC）