Options. Not to be overlooked is the microcontroller circuit.. In addition, only a few peripherals, such as a clock, the USB controller and the voltage adjustment and stabilization for an externally connected power. Supply., And that brings us to the first connection. – A normal plug in power supply can be connected here with a voltage between 7 and 12V.. This refers to the Arduino Uno, which itself runs on 5V.. There are also boards with 3.3V. Be sure to check the documentation. First. Make sure the polarity is correct. Positive, pole inside., But we dont need that for our first experiments. When the Arduino is connected to the PC, it receives its power supply from the USB port. Lets. Look at the two side: rows of connectors. Pins 0 to 13. Can be used as digital inputs and outputs. Switching is done by software., Pins 0 and 1 should be left free when the USB cable is connected, as this is how the Arduino communicates with the PC.. On the other side, there are analog inputs A0 to A5. Analogue sensors, such as photoresistors or temperature. Sensors can be connected here. Next to it are the connections for the supply voltage for our external wiring.. You may have noticed that there is no analogue output.. How can we then steplessly control our peripherals, for example, dimming, an LED or adjusting the motor speed? Some of the digital connections are marked with a tilde.. So here are the connections. 3, 5, 6 and 9 to 11.

. Here stands: digital PWM and that stands for pulse width, modulation., The digital outputs only know two states.. If the output voltage is clocked, however, the energy at the output can be infinitely adjusted via the pulse width. And there we are with the levels.. The Arduino recognizes voltages up to 1.5V as low level and above 3V as high.. The limits for the 3.3V boards are 1V or 2V. In general. The connections should not be subjected to voltages that are above the operating voltage.. The maximum current carrying capacity is 40mA. Thats enough to connect an LED directly.. Appropriate drivers are required for larger currents., Be careful when connecting inductive loads such as relays or motors.. The voltage peaks that occur must be mitigated in any case and kept away from the controller.. Finally, lets take another look at the board.: There are 4 LEDs for function. Control. A power LED that lights up as soon as the operating voltage is applied.. The TX and RX LEDs indicate communication with the PC and flicker when programming the chip or when outputting serial data to the PC.. The fourth LED is internally connected to pin 13.. This allows tests to be carried out without first having to connect an external, LED. And thats exactly what were going to do next time we get the Arduino up and running.