The OLED displays the light sensitivity value

The OLED displays the light sensitivity value1、software-hardware2、Brief principle2.1、Hardware schematic diagram2.2、Physical connection diagram2.3、Principle of control3、Engineering configuration3.1、Notes3.2、Pin configuration4、Main FunctionUser function5、Experimental phenomenon

This tutorial demonstrates how a 0.91 inch OLED driven by a hardware I2C displays the converted values of a photosensor ADC.

1、software-hardware

STM32F103CubeIDE
STM32 robot expansion board
0.91 inch OLED display, in which the photosensitive sensor is integrated on the development board
Type-C cable or ST-Link
Download or simulate the program of the development board

2、Brief principle

2.1、Hardware schematic diagram

The schematic only shows the I2C (I2C1) and photosensor interfaces used in the tutorial

2.2、Physical connection diagram

OLED	STM32 board
VCC	VCC
SCL	SCL
SDA	SDA
GND	GND

2.3、Principle of control

I2C

The use of I2C1 peripheral interface and 0.91 inch OLED display for communication, I2C related knowledge will not be introduced, you can see before [3, development board basic tutorial: I2C Communication]

ADC

By using an ADC (analog-to-digital converter), the analog voltage output by the photosensor can be converted to a digital value.

The STM32F103ZET6 contains three 12-bit analog-to-digital converters, and the converted value range is 0 to 2^12-1 (i.e., 0 to 4095).

Photosensitive sensor (development board integrated)	Corresponding pin
LIGHT (analog signal output)	PF8（ADC3_IN6）

OLED

product	0.91 inch OLED screen
resolution	128*32
Control chip	SSD1306
Means of communication	I2C（IIC）
Voltage of operation	3.3~5V
I2C interface	VCC：Power supply positive（3.3/5V） GND：Power supply ground SCL：I2C bus clock signal SDA：I2C bus data signal

3、Engineering configuration

Project Configuration: Prompts for configuration options in the STM32CubeIDE project configuration process

3.1、Notes

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

The project configuration part, which is not omitted, is the key point to configure in this tutorial.


Please refer to [2, development environment construction and use: STM32CubeIDE installation - Use] to understand how to configure the omitted part of the project

3.2、Pin configuration

ADC

I2C

Advanced Settings

Generating code

4、Main Function

This part mainly introduces the functional code written by users. Detailed code can be opened by yourself in the project file we provide, and enter the Bsp folder to view the source code. .

User function

Many of the common HAL library functions were covered in Chapter 3, but they will not be covered here.

function：user_lightseek_detect

Function prototypes	void user_lightseek_detect(void)
Functional Description	OLED displays the resistance of the light sensitivity
Input parameters	None
Return value	None

function：Adc_Get_seek_finally

Function prototypes	uint32_t Adc_Get_seek_finally(void)
Functional Description	The photosensitive voltage is converted to resistance
Input parameters	None
Return value	Value of resistance

function：Adc_Get_seek_finally

Function prototypes	uint16_t Adc_Get_seek(uint32_t ch)
Functional Description	The photosensitive voltage was collected
Input parameters	ADC channel
Return value	Value of voltage

5、Experimental phenomenon

After downloading the program successfully, press the RESET button of the development board to observe the OLED display


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Program download can refer to [2, development environment construction and use: program download and simulation]

Phenomenon:：

OLED display The first line shows oled init success! (boot display once), the third row shows the photosensitive sensor resistance value.


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The experimental phenomenon can be seen [OLED display light sensitivity value _ Experimental phenomenon.mp4]