* Photo-resistor module outputs a low voltage under a bright condition, and vice versa.
* Shine your phone’s flashlight on the photoresistor
* The sensor’s output voltage should decreases
* Try different voltage thresholds to adjust the detection sensitivity.
* Create a new program named as ‘**TU\_arduino\_AnalogIn**.**ino**
* Click on **Upload** button.
* Open ‘Tera Term’ and make New Connection.
```c
const int ledPin = 13;
const int cdsPin = 0;
float measure;
int ledState = LOW;
void setup() {
pinMode(ledPin, OUTPUT);
Serial.begin(9600);
}
void loop() {
measure = analogRead(cdsPin); // mapping(0 ~ 3.3V -> 0 ~ 1023)
measure = measure * 3300 / 1024; // [mV] (0 ~ 1023 -> 0 ~ 3300[mV])
Serial.print("measure = ");
Serial.print(measure);
Serial.println(" [mV]");
if (measure > 2500) ledState = HIGH;
else ledState = LOW;
digitalWrite(ledPin, ledState);
delay(200);
}
```
####
## ADC Library (ecADC.h)
Download the exercise files.
* [ecADC2\_student.c](https://github.com/ykkimhgu/EC-student/blob/main/include/lib-student), [ecADC2\_student.h](https://github.com/ykkimhgu/EC-student/blob/main/include/lib-student)
Change the file names as `ecADC2.c, h`
> You must update your header files in the directory `EC\include\`. and add in `ecSTM32F4v2.h`
**ecADC.h**
{% code expandable="true" %}
```cpp
////////////////////////////////////////////////////////////////
/* Basic Syntax */
////////////////////////////////////////////////////////////////
// Analog pin, ADC clock, 12-bit, sampling time, one-channel sequence.
// software trigger, one conversion,
void ADC_init(PinName_t pinName);
// single conversion : start, wait for EOC, return the result.
uint32_t ADC_read_poll(void);
// Use inside ADC_IRQHandler() after is_ADC_EOC().
uint32_t ADC_read(void);
// Hardware trigger : the TIMx UPDATE event (TRGO) every msec.
// Only TIM2 and TIM3 reach the ADC regular group on the F411
int ADC_trigger_init(TIM_TypeDef *TIMx, uint32_t msec, uint32_t edge);
////////////////////////////////////////////////////////////////
/* JADC : the INJECTED group, */
////////////////////////////////////////////////////////////////
// Analog pin + one-channel injected sequence.
// software trigger, no interrupt,
void JADC_init(PinName_t pinName);
// SW triggered single injected conversion
uint32_t JADC_read_poll(void);
// Result of the n-th conversion of the injected sequence, JDRn = 1 ~ 4.
// Reading JDRx does NOT clear JEOC - call clear_ADC_JEOC() yourself.
uint32_t JADC_read(uint32_t JDRn);
// Hardware trigger : the TIMx UPDATE event (TRGO) every msec.
// Also enables the JEOC interrupt, TIM1, TIM2, TIM4, TIM5
// Returns 0 on success, -1 if TIMx has no TRGO entry for the injected group.
int JADC_trigger_init(TIM_TypeDef *TIMx, uint32_t msec, uint32_t edge);
```
{% endcode %}
### Example Code: Polling Analog Read
* Two Sensors(Channels), Single Conversion
* **Trigger: SW trigger, Polling**
* Injected Group
* JSQ1=ADC\_CH\_8(PB\_0)
* JSQ2=ADC\_CH\_9(PB\_1)
* Regular Group
* SQ1=ADC\_CH\_8(PB\_0)
* SQ2=ADC\_CH\_9(PB\_1)
{% tabs %}
{% tab title="JADC-Polling" %}
```c
/*----------------------------------------------------------------\
@ Embedded Controller by Young-Keun Kim - Handong Global University
Author : [ YOUR NAME GOES HERE !!!!!]
Created : 10-23-2026
Modified : 00-00-2026 [WRITE THE DATE!!!!]
Language/ver : C in VS Code
Description : Tutorial - ADC polling, injected group (ecADC2)
/----------------------------------------------------------------*/
#include "ecSTM32F4v2.h"
#include "ecADC2.h"
//Analog Sensor 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){
value1 = JADC_read_poll(); // one start converts the sequence
value2 = JADC_read(2); // JDR2 already holds conversion 2
printf("value1 = %lu \r\n",value1);
printf("value2 = %lu \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
// JADC Init Default: SW trigger, no interrupt
JADC_init(PB_0);
JADC_init(PB_1);
// JADC channel sequence setting
JADC_sequence(seqCHn, 2);
}
```
{% endtab %}
{% tab title="ADC-Polling" %}
```c
/*----------------------------------------------------------------\
@ Embedded Controller by Young-Keun Kim - Handong Global University
Author : [ YOUR NAME GOES HERE !!!!!]
Created : 10-23-2026
Modified : 00-00-2026 [WRITE THE DATE!!!!]
Language/ver : C in VS Code
Description : Tutorial - ADC polling, regular group (ecADC2)
/----------------------------------------------------------------*/
#include "ecSTM32F4v2.h"
#include "ecADC2.h"
//Analog Sensor 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){
value1 = ADC_read_poll(); // SQ1 : PB_0
value2 = ADC_read_poll(); // SQ2 : PB_1
printf("value1 = %lu \r\n",value1);
printf("value2 = %lu \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: SW trigger, single conversion, no interrupt
ADC_init(PB_0);
ADC_init(PB_1);
// ADC channel sequence setting
ADC_sequence(seqCHn, 2);
}
```
{% endtab %}
{% endtabs %}
### Example Code: Timer-Triggered, EOC Interrupt
* Two Sensors(Channels), Single Conversion
* **Trigger: Timer trigger**
* Injected Group: TIM1,2,4,5 only
* Regular Group: TIM 2,3 only
* Injected Group : TIM5
* JSQ1=ADC\_CH\_8(PB\_0)
* JSQ2=ADC\_CH\_9(PB\_1)
* Regular Group : TIM3
* SQ1=ADC\_CH\_8(PB\_0)
* SQ2=ADC\_CH\_9(PB\_1)
{% tabs %}
{% tab title="JADC-Interrupt" %}
```c
/*----------------------------------------------------------------\
@ Embedded Controller by Young-Keun Kim - Handong Global University
Author : [ YOUR NAME GOES HERE !!!!!]
Created : 10-23-2026
Modified : 00-00-2026 [WRITE THE DATE!!!!]
Language/ver : C in VS Code
Description : Tutorial - ADC timer-triggered + interrupt, injected group (ecADC2)
/----------------------------------------------------------------*/
#include "ecSTM32F4v2.h"
#include "ecADC2.h"
//Analog Sensor parameter//
volatile 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 = %lu \r\n",value1);
printf("value2 = %lu \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
// JADC Init Default: SW trigger, no interrupt
JADC_init(PB_0);
JADC_init(PB_1);
// JADC channel sequence setting
JADC_sequence(seqCHn, 2);
// HW trigger : TIM5 TRGO @ 1msec - enables JEOC interrupt
JADC_trigger_init(TIM5, 1, ADC_RISE);
}
void ADC_IRQHandler(void){
if(is_ADC_JEOC()){ // one JEOC after the whole sequence
value1 = JADC_read(1);
value2 = JADC_read(2);
clear_ADC_JEOC();
}
}
```
{% endtab %}
{% tab title="ADC-Interrupt" %}
```c
/*----------------------------------------------------------------\
@ Embedded Controller by Young-Keun Kim - Handong Global University
Author : [ YOUR NAME GOES HERE !!!!!]
Created : 10-23-2026
Modified : 00-00-2026 [WRITE THE DATE!!!!]
Language/ver : C in VS Code
Description : Tutorial - ADC timer-triggered + interrupt, regular group (ecADC2)
/----------------------------------------------------------------*/
#include "ecSTM32F4v2.h"
#include "ecADC2.h"
//Analog Sensor parameter//
volatile uint32_t value1, value2;
volatile uint32_t seqIdx = 0; // EOC fires once per conversion
PinName_t seqCHn[2] = {PB_0, PB_1};
void setup(void);
int main(void) {
// Initialiization --------------------------------------------------------
setup();
// Inifinite Loop ----------------------------------------------------------
while(1){
printf("value1 = %lu \r\n",value1);
printf("value2 = %lu \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: SW trigger, single conversion, no interrupt
ADC_init(PB_0);
ADC_init(PB_1);
// ADC channel sequence setting
ADC_sequence(seqCHn, 2);
// HW trigger : TIM3 TRGO @ 1msec, enables EOC interrupt
ADC_trigger_init(TIM3, 1, ADC_RISE);
}
void ADC_IRQHandler(void){
if(is_ADC_OVR()) clear_ADC_OVR();
if(is_ADC_EOC()){ // EOC per conversion : SQ1, then SQ2
if(seqIdx == 0) value1 = ADC_read();
else value2 = ADC_read();
seqIdx ^= 1;
}
}
```
{% endtab %}
{% endtabs %}
## Problem: Measurement from multiple analog sensors
### IR Reflective Sensors (TCRT 5000)
First, download and read IR Reflective Sensor(TCRT 5000): [Spec Sheet](https://www.devicemart.co.kr/goods/download?id=1327416\&rank=1)
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.
### Procedure
1. Create a new project under the directory `\repos\EC\LAB\LAB_ADC`
* The Enviornment 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\. use **ecSTM32F411.h**. This header should be defined as explained in
### Configuration
| Type | Port - Pin | Configuration |
| ---------------- | ----------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------- |
| **System Clock** | | PLL 84MHz |
| **ADC (JADC)** | PB\_0: ADC1\_CH8 (1st channel)
PB\_1: ADC1\_CH9 (2nd channel)
Two channels in regular group( or JADC)
External Trigger: Timer3 @ 1kHz, Detection on Rising Edge