This project involves in measurement of light intensity using BH1750 sensor via STM32WB55-DK. Measured data will be updated on the OLED. The same data will be communicated over BLE to a PC or mobile.
Need for light intensity measurement:
Light is an essential factor in maintaining plants. The rate of growth and length of time a plant remains active is dependent on the amount of light it receives. Light energy is used in photosynthesis, the plant’s most basic metabolic process. Light intensity influences the manufacture of plant food, stem length, leaf color and flowering. Generally speaking, plants grown in low light tend to be spindly with light green leaves. A similar plant grown in very bright light tends to be shorter, better branches, and have larger, dark green leaves.
Solution:
In this work a light intensity meter is designed with BLE communication support using STM32WB55-DK[1] and BH1750 light intensity sensor[2].  BH1750 light sensor is used to detect the ambient light intensity, the sensor is having I2C bus interface and It is possible to detect wide range at High resolution.( 1 - 65535 lx ).
Light sensor is interfaced through the I2C port of the STM32WB55-DK (SDA-PA10, SCL-PB8)  measured light intensity data are updated on the on-board OLED display at regular intervals. STM32WB55-DK configured as a BLE peripheral notify the sensor data with a BLE central (PC or Mobile).

Firmware for STM32WB55-DK is developed under Arduino IDE and BLE central device (PC/Mobile) has utilized web BLE API along with HTML and java script.[3].

kindly refer [4,5] for BLE firmware and Arduino IDE usage with discovery board.



References:
1. https://www.st.com/en/evaluation-tools/stm32wb5mm-dk.html
2. https://www.electronicshub.org/bh1750-ambient-light-sensor/
3. https://randomnerdtutorials.com/esp32-bluetooth-guide/ 
4. https://wiki.st.com/stm32mcu/wiki/Connectivity:STM32WB_BLE_Arduino
5. https://www.elektormagazine.com/labs/truck-dock-automation