LAB: ADC - IR reflective sensor

Date: 2025-11-06

Author/Partner:

Github: repository link

Demo Video: Youtube link

PDF version:

Introduction

Create a simple program that uses ADCs to use analog sensors. For this lab, we will use two IR reflective sensors.

The ADCs are triggered by a timer at the given sampling rate.

This lab will be extended to Project: Line Tracing Car

You must submit

LAB Report (*.md & *.pdf)
Zip source files(main*.c, ecRCC.h, ecGPIO.h, ecSysTick.c etc...).
- Only the source files. Do not submit project files

Requirement

Hardware

MCU
- NUCLEO-F411RE
Actuator/Sensor/Others:
- IR Reflective Sensor (TCRT 5000) x2

Software

Keil uVision, CMSIS, EC_HAL library

Problem 0: STM-Arduino

Procedure

Create a new project under the directory\repos\EC\LAB\LAB_ADC
Follow the tutorial: ADC with photodector and sound sensor

Tutorial: arduino-stm32 Part2 | ECykkim.gitbook.io

Problem 1: EC library

(Option 1) Use the provided library

Download Library Header Files (solution)

ecADC2.h, ecADC2.c

/////////////////////////////////////////////////////
// ADC default setting
/////////////////////////////////////////////////////

// ADC init
// Default:  one-channel mode, continuous conversion
// Default: HW trigger - TIM3 counter, 1msec
void ADC_init(PinName_t pinName);
void JADC_init(PinName_t pinName);


// Multi-Channel Scan Sequence 
void ADC_sequence(PinName_t *seqCHn, int seqCHnums); 
void JADC_sequence(PinName_t *seqCHn, int seqCHnums); 


// ADC start
void ADC_start(void);

// flag for ADC interrupt
uint32_t is_ADC_EOC(void);
uint32_t is_ADC_OVR(void);
void clear_ADC_OVR(void);
uint32_t is_ADC_JEOC(void);
void clear_ADC_JEOC(void);

// read ADC value
uint32_t ADC_read(void);




/////////////////////////////////////////////////////
// Advanced Setting
/////////////////////////////////////////////////////
// Conversion mode change: CONT, SINGLE / Operate both ADC,JADC
void ADC_conversion(int convMode); 					
void ADC_trigger(TIM_TypeDef* TIMx, int msec, int edge);

// Private Function
void ADC_pinmap(PinName_t pinName, uint32_t *chN);

(Option 2) Create your own library

Download the exercise files.

Change the file names as

ecADC2.c
ecADC2.h

ecADC2.h

Fill-In missing code in ecADC2_student.c

You must update your header files in the directory EC\include\. and add in ecSTM32F4v2.h

void ADC_init(PinName_t pinName){
// ...
// ...
	// 2. Regular / Injection Group 
	//Regular: SQRx, Injection: JSQx

	// 3. Repetition: Single scan or Continuous scan conversion
	ADC1->CR2 |= ___________;      			// default : Continuous conversion mode	
	
	// 4. Single(one) Channel or Scan(multi-channel) mode  
	// Configure the sequence length		// default: one-channel length
	ADC1->SQR1 &= ___________; 				// 0000: one channel length in the regular channel conversion sequence
	
	// Configure the multiple channel sampling sequence 
	ADC1->SQR3 &= ~ADC_SQR3_SQ1;			// SQ1 clear 
	ADC1->SQR3 |= ___________; 				// Choose the first channelID to sample
	
	// Default:  Single(one-channel) Channel mode 
	ADC1->CR1 &= ___________;				// 0: One-channel mode 		
	
	// 5. Interrupt Enable
	// Enable EOC(conversion) interrupt. 
	ADC1->CR1 &= ~ADC_CR1_EOCIE;          	// Interrupt reset
	ADC1->CR1 |= ___________;           	// Interrupt enable
	
// ...
// ...
}

void JADC_init(PinName_t pinName){
// ...
// ...
	// 2. Injection Group 
	//    Injection: JSQx

	// 3. Repetition: Single or Continuous conversion
	ADC1->CR2 |= _____________;     		// Enable Continuous conversion mode	
	
	// 4. Single Channel or Scan mode
	//  - Single Channel: scan mode, right alignment	
	ADC1->CR1 |= _____________;			// 1: Scan mode enable 
	ADC1->CR2 &= _____________;   			// 0: Right alignment	

	// Configure the injected channel sequence length
	ADC1->JSQR &= _____________; 			// 00: conversion in the inject channel

	// Configure the injected channel sequence 
	ADC1->JSQR &= ~ADC_JSQR_JSQ1;			// SQ1 clear bits
	ADC1->JSQR |= _____________; 			// Choose the channel to convert firstly

	// 5. Interrupt Enable
	// Enable JEOC(conversion) interrupt.
	ADC1->CR1 &= ~ADC_CR1_JEOCIE;   		// JEOC interrupt reset
	ADC1->CR1 |= _____________;			// JEOC interrupt enable
		
// ...
// ...
}

Example Code

Check your library files by running the following examples.

Example 1: One Analog sensor (ADC)

Single-Channel, Continuous Scan
1msec ADC triggering with TIM3

#include "ecSTM32F4v2.h"
// #include "ecADC.h"


//IR parameter//
uint32_t value;

void setup(void);
	
int main(void) { 
	
	// Initialiization --------------------------------------------------------
	setup();
	
	// Inifinite Loop ----------------------------------------------------------
	while(1){
		printf("value = %d \r\n",value);
		printf("\r\n");
		delay_ms(1000);
	}
}

// Initialiization 
void setup(void)
{	
	RCC_PLL_init();		// System Clock = 84MHz
	UART2_init();		// UART2 Init
	SysTick_init();		// SysTick Init
	ADC_init(PB_0);		// Default: HW triggered by TIM3 counter @ 1msec
}

// ADC Interrupt - End-of-Conversion
void ADC_IRQHandler(void){
	if(is_ADC_EOC()) {
		// if(is_ADC_OVR()) clear_ADC_OVR();	
		// User Code Goes Here
		value = ADC_read();
		// clear_ADC_EOC();  // Reading ADC clears EOC flag
	}		
}

Example 2: Multiple Analog sensors (JADC)

Multi-Channel(2 channels), Continuous Scan
1msec ADC triggering with TIM3
(ADC) Channel Sequence:
- SQ1=ADC_CH_8(PB_0) to SQ2=ADC_CH_9(PB_1)
(JADC): Channel Sequence:
- JSQ1=ADC_CH_8(PB_0)(PB_0) to JSQ1=ADC_CH_9(PB_1)

Use JADC instead of ADC for multiple-channel ADC

JADC: Has its own data register for each ADC channels

#include "ecSTM32F4v2.h"
// #include "ecADC.h"

//IR parameter//
uint32_t value1, value2;
PinName_t seqCHn[2] = {PB_0, PB_1};

void setup(void);

int main(void) { 
	// Initialiization --------------------------------------------------------
	setup();
	
	// Inifinite Loop ----------------------------------------------------------
	while(1){
		printf("value1 = %d \r\n",value1);
		printf("value2 = %d \r\n",value2);
		printf("\r\n");
		
		delay_ms(1000);
	}
}

// Initialiization 
void setup(void)
{	
	RCC_PLL_init();                 // System Clock = 84MHz
	UART2_init();			// UART2 Init
	SysTick_init();			// SysTick Init
	
	// ADC Init  Default: HW triggered by TIM3 counter @ 1msec
	JADC_init(PB_0);
	JADC_init(PB_1);

	// ADC channel sequence setting
	JADC_sequence(seqCHn, 2);
}


void ADC_IRQHandler(void){
	// if(is_ADC_OVR()) clear_ADC_OVR();	
	if(is_ADC_JEOC()){		// after finishing sequence ADC
		value1 = JADC_read(1);
		value2 = JADC_read(2);
		clear_ADC_JEOC();
	}
}

ADC: Shares the same data register from multiple channels

#include "ecSTM32F4v2.h"
// #include "ecADC.h"

//IR parameter//
uint32_t value1, value2;
int flag = 0;
PinName_t seqCHn[2] = {PB_0, PB_1};

void setup(void);

int main(void) { 
	// Initialiization --------------------------------------------------------
	setup();
	
	// Inifinite Loop ----------------------------------------------------------
	while(1){
		printf("value1 = %d \r\n",value1);
		printf("value2 = %d \r\n",value2);
		printf("\r\n");
		
		delay_ms(1000);
	}
}

// Initialiization 
void setup(void)
{	
	RCC_PLL_init();                         // System Clock = 84MHz
	UART2_init();				// UART2 Init
	SysTick_init();				// SysTick Init
	
	// ADC Init  Default: HW triggered by TIM3 counter @ 1msec
	ADC_init(PB_0);
	ADC_init(PB_1);

	// ADC channel sequence setting
	ADC_sequence(seqCHn, 2);
}


void ADC_IRQHandler(void){
	if(is_ADC_OVR())
		clear_ADC_OVR();
	
	if(is_ADC_EOC()){		// after finishing sequence
		if (flag==0)
			value1 = ADC_read();  
		else if (flag==1)
			value2 = ADC_read();
			
		flag =! flag;		// flag toggle
	}
}

Problem 2: Measurement from multiple analog sensors

IR Reflective Sensors (TCRT 5000)

First, download and read IR Reflective Sensor(TCRT 5000): Spec Sheet

TCRT5000 and TCRT5000L are reflective sensors that include an infrared emitter and phototransistor in a leaded package, which blocks visible light.

The HC-SR04 Ultrasonic Range Sensor Features:

Input Voltage : 5V
Detector type: phototransistor
Operating range within > 20 % relative collector current: 0.2 mm to 15 mm
Emitter wavelength: 950 nm

APPLICATIONS

Position sensor for shaft encoder
Detection of reflective material such as paper, IBM cards, magnetic tapes etc.
Limit switch for mechanical motions in VCR

Procedure

Create a new project under the directory \repos\EC\LAB\LAB_ADC

The project name is “LAB_ADC_IR”
Create a new source file named as “LAB_ADC_IR.c”

You MUST write your name on the source file inside the comment section.

2. Update and use ecSTM32F411.h. This header should be defined as explained in

Configuration

Type

Port - Pin

Configuration

System Clock

PLL 84MHz

GPIO

PB_0 PB_1

Analog Mode No Pull-up Pull-down

ADC (JADC)

PB_0: ADC1_CH8 (1st channel) PB_1: ADC1_CH9 (2nd channel)

ADC Clock Prescaler /8 12-bit resolution, right alignment Continuous Conversion mode Scan mode: Two channels in regular group External Trigger (Timer3 Trigger) @ 1kHz Trigger Detection on Rising Edge

TIM3

Up-Counter, Counter CLK 1kHz OC1M(Output Compare 1 Mode) : PWM mode 1 Master Mode Selection: (Trigger) OC1REF

Line Tracing

Create a logic to trace a dark line on white background surface for your RC car.
Use 2 IR reflective sensors to detect if the black line is in between the sensors. It should display whether the system needs to move Left or Right to keep the line between sensors.
Set the ADC sampling rate trigger to be 1KHz
Determine the threshold value to differentiate dark and white surface of the object.
Display (1) and (2) on serial monitor of Tera-Term. Print the values every second.
(1) reflection value of IR1 and IR2
(2) print ‘GO LEFT’ or ‘GO ‘RIGHT’