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The following image shows how to connect a push button switch to an Arduino Uno using a pull-down resistor. Connect a Push Button Switch to an Arduino Uno The following sub-sections show how to connect a push button switch to an Arduino Uno and then an Arduino MEGA 2560 using a breadboard circuit. Arduino Push Button Switch Breadboard Circuit Afterwards, push the button to verify that the pins are now electrically joined. In other words, test between pins on the same side of the switch to verify that they are open circuit. Test the functionality of the switch with the multimeter afterwards. First plug the switch into a breadboard to make it easier to use the multimeter probes on the switch pins. Test the switch by checking that the opposite pins are one continuous metal conductor. See the article on basic continuity testing with a multimeter. Put your multimeter onto the continuity setting. Release the button and the connection is broken again. When the button is pushed, the metal strips electrically join together. Push Button Switch Internal WiringĪs can be seen in the image, opposite pins are electrically connected and essentially one piece of metal. On the right, the switch shows the internal connections of the pins. The push button switch on the left shows the orientation of the push button, which is the orientation of both push buttons in the image. As can be seen in the following image, pins opposite each other on a push button switch are connected. Get a momentary push button switch ready to plug into the breadboard circuit. Refer back to part 6 of this tutorial, Build a Breadboard Circuit for Beginners, for more information on reading resistor values. Put the three zeros after the first two digits and we get 10,000 or 10k. Orange has a value of 3, which means three zeros. This means that the resistor value starts with 10. 10k Resistor Colors and ValuesĪs the above image shows, the resistor brown band has a value of 1 and black a value of 0. A 5% tolerance 10k resistor has the colors brown, black and orange, as shown in the image below.
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The letter k in 10k is short for kilo which means 1000. Get a 10k ResistorĪ 10k resistor has a value of 10,000 ohms. Find the same information for Arduino MEGA 2560 boards in the Ultimate Arduino MEGA 2560 Hardware Manual. Although a 10k resistor is specified, any resistor from around 4k7 to 20k works in the circuit.įor more information on pull-up resistors, pull-down resistors, and other Arduino input pin configurations, see the Ultimate Arduino Uno Hardware Manual for Arduino Uno boards. In fact a 10k resistor is used in the circuit. Pull-down describes the function of the resistor in the circuit, it is not a special type of resistor. In this tutorial, a pull-down resistor is used in conjunction with the push button switch. There is more than one way to connect a push button switch to an Arduino. Momentary Push Button Switches How to Connect a Push Button Switch to an Arduino Connect the wire link to the breadboard circuit to simulate closing the switch, and disconnect the wire link to simulate opening the switch. Use a wire link instead if you do not have a push button switch. The image below shows examples of this type of switch. When the switch is released, the contacts open. Momentary means that the switch stays closed only while pushed. They don't appear to be labled on the added pins next to AREF, so picking the wrong one on this attempt is 50/50.A push button switch called a momentary push button switch is used in this tutorial. Can any harm arise from accidentally swapping the SDA for the SCL? I'm thinking no, as its just a zero to 5 volt square wave on either. It all works so slick and easy like everything else with the Duemilanove, just not with the Mega 2560 R3.įor fun, I am going to try the other two SDA and SCL pins. I checked the output on the Mega's I2C pins with an oscilloscope, and there is certainly a 0 to 5v signal coming out of both SCL and SDA on the Mega.
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I've tried a variety of values of pull up resistors, and also no pull ups, and still get no I2C function on the Mega. I have another Mega on order, and perhaps it will be the same, or it might work. When I run any of 3 I2C scanners on my Mega, nothing shows up for the I2C devices. I now know that the devices, a compass and lcd work perfectly with my Duemilanove. I've been struggling with an otherwise excellent Mega 2560 R3, that for some reason doesn't communicate with any I2C device.