Sometimes you may see in a particular device’s data sheet the use of different value pull-up resistors – for example 4.7k ohm.
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Like anything, some testing on a breadboard or prototype circuit will determine their necessity. However if you are running a string of devices, use two 10 kilo ohm resistors. If you are only using one I2C device, the pull-up resistors are (normally) not required, as the ATmega328 microcontroller in our Arduino has them built-in. If you have another type of board, check your data sheet or try the Arduino team’s hardware website.Īnd finally, if you are using a bare DIP ATmega328-PU microcontroller, you will use pins 27 for SDA and 28 for SCL. The bus wiring is simple: If you are using an Arduino Mega, SDA is pin 20 and SCL is 21, so note that shields with I2C need to be specifically for the Mega. Those of you with an Arduino Uno or 100% compatible board, you will be using pins A4 for SDA (data) and A5 for SCL (clock): There are many applications, such a real-time clocks, digital potentiometers, temperature sensors, digital compasses, memory chips, FM radio circuits, I/O expanders, LCD controllers, amplifiers, and so on.Īnd you can have more than one on the bus at any time, in fact the maximum number of I2C devices used at any one time is 112.įrom a hardware perspective, the wiring is very easy. And our Arduino boards can control them all. Here is a nice introductory video from NXP:Īs there are literally thousands of components that use the I2C interface. This reduced the number of wires to two (SDA – data, and SCL – clock). In the late 1970s, Philips’ semiconductor division (now NXP) saw the need for simplifying and standardising the data lines that travel between various integrated circuits in their products. I2C is an acronym for “Inter-Integrated Circuit”. Furthermore it would be in your interest to have an understanding of the binary, binary-coded decimal and hexadecimal number systems. In this article we will learn the necessary theory, and then apply it by controlling a variety of devices. The I2C bus can be a complex interface to master, so we will do my best to simplify it for you. The machine’s frame is a combination of wood, aluminum extrusion, and 3D-printed parts.In this first of several tutorials we are going to investigate the I2C data bus, and how we can control devices using it with our Arduino systems. The display is a Nextion NX3224K028 2.8″ resistive touchscreen with a resolution of 320×240, which has a custom interface programmed by Mr Innovative. A high-torque stepper motor in a servo motor package actuates a linkage that pushes the cutting blade. A NEMA 17 stepper motors drives a wheel that feeds the heat shrink tubing. It will continue to snip off sections of tubing, all of the same length, until it runs out of heat shrink to work with.Īn Arduino Nano board controls the machine through a custom PCB that contains two A4988 stepper motor drivers. The user inserts one end of the tubing into the machine, sets the length via a touchscreen interface, and the machine takes care of the rest. This machine is similar, but works with a single spool of heat shrink tubing. Mr Innovative built similar machines in the past, including one that feeds four different wire spools and cuts them to desired lengths. That’s why Mr Innovative used an Arduino to build this handy machine that cuts heat shrink tubing automatically. But cutting heat shrink tubing to length can be a time-consuming process if you have many wires to protect. Most people use either electrical tape or heat shrink tubing for the job.
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Because they can move around and touch each other or the enclosure, you need to protect the bare wire from shorts. Solder joints on PCBs don’t usually require extra protection, but loose wires are a different story.