“It’s hard to be a bright light in a dim world.” 
 – Gary Starta

A common 5mm LED isn’t the best in every situation, often a bit more power is required. That’s why I’ve connected a 3W power RGB LED to an STM32F0-Discovery board.



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STM32F4-Discovery LCD Touchscreen

It’s time to write about a more complex but interesting connection with the STM32F4-Discovery board. Since I started developing with electronics, I’ve found a lot of applications in which an LCD is needed or can be an added value, specially if it includes a Touchscreen.


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HC-SR04 Ultrasonic Range Finder

The HC-SR04 ultrasonic sensor uses sonar to determine distance to an object. It offers excellent non-contact range detection with high accuracy and stable readings in an easy-to-use package, from about 3cm to 300cm. Its operation is not affected by sunlight or black material like other kind of sensor, although acoustically soft materials like cloth can be difficult to detect – at least in the far range. It comes complete with ultrasonic transmitter and receiver module.


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Interfacing DHT22 sensor

The DHT22 (also known as AM2302) is a cheap temperature and humidity sensor with an impressive performance! It uses a capacitive humidity sensor and a thermistor to measure the air, and send out a digital signal on the data pin (no analog input pins needed). Its fairly simple to use, but requires careful timing to grab data. The only real CON of this sensor is that you can only get new data from it once every 2 seconds. It is provided with a single wire digital interface. The sensor is calibrated and only requires a single pull-up resistor (any value between 3.6k and 10k should work fine) on the dataline to communicate correctly. Compared to the cheaper (and wider diffused) DHT11, this module is much more precise, more accurate and works in a bigger range of temperature/humidity.


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