Have you ever used an Arduino Mega 2560 (or a similar board) and, at some point in the development process, experienced the LED mysteriously stopping to blink, garbled text being printed, or funny artifacts appearing in pictures? And all that without any apparent reason or any error or warning message? If you want to know what is behind it and how to solve this problem, read on.
Continue readingCategory: Library
In-depth discussions of (aspects of) some libraries
Connecting the AVR-IoT Cellular Mini Board to the Internet
When you want to connect a sensor or actuator to the Internet and there is no WLAN around, then the next best option is LPWAN (Low-Power Wide Area Network). In this blog post, I will describe how to connect a sensor to a website using the AVR-IoT Cellular Mini board by Microchip.
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Software I2C Multiplexer
What can you do to connect many I2C devices with the same device address to an MCU? Most often, the advice is to use hardware solutions. Here, we will look at how to solve the problem with software employing the FlexWire library.
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Replacing the Wire Library—Sometimes
The Wire library is the one that connects your Arduino to sensors and actuators that communicate using the I2C protocol. Unfortunately, this library has a lot of shortcomings, and often you want to replace it with a different I2C library. Replacing the Wire library on a per-sketch basis turns out to be more complicated than one would expect. In this blog post, I describe an easy way to accomplish that.
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Calibrating Your AVR MCU
In building one’s own MCU board, one often does not use a crystal or resonator. Instead, the internal RC-oscillator is employed, which can be quite inaccurate. Similarly, if one wants to use the internal reference voltage to measure the supply voltage, it turns out that the reference voltage can deviate from its nominal value quite a lot. Both, the RC-oscillator and the internal reference voltage can be calibrated, though. In this blog post, I describe a simple method to calibrate both using only a UNO board and a multimeter employing the avrCalibrate library.
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Drifting in the Flow of Time
What happens if you take a dozen clocks and throw them into the flow of time?
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One Line Only
A new Arduino library has seen the light of day: SingleWireSerial. It supports single-wire, asynchronous serial, half-duplex communication. By using the input capture feature of the AVR MCUs, it is extremely accurate and supports bit rates up to 250 kbps robustly. And contrary to its title, one can even use it in a two-wire setting.
Communicating Asynchronously
Serial asynchronous communication is one of the most common forms of communication between two electronic devices. Let us see, what Arduino libraries are there to support it, and let us check, how well they perform.
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Is any Input Available?
The SoftwareSerial class has the available() method, which returns the number of characters that have been already received but not yet read. This is very similar to what the standard Serial.available() method offers. There is an interesting difference, though. A call to SoftwareSerial.available() is significantly slower than a call to Serial.available(). We will look for the deeper reason for this strange behavior and I will show you three ways how to fix it.
EDIT: The problem will vanish with Arduino version 1.8.17
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Connecting the Dots
If you want to drive a 5×7 dot matrix display directly from your MCU, I have the right Arduino library for you. Flexible, easy to use, supporting low power operation, and a low memory footprint: DotMatrix5x7.
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