Great code however am having strange outputįor the source value of 220 I have a known R2 of 10 OhmÄ«ut the output from the following code is showing 5274. If itâs your connections⦠well, that should have been the first thing you checked! Reply If that doesnât fix it, then either your entire Arduino is screwed up, or itâs your connections. If itâs your analog pin, simply moving the wire from analog pin 0 to analog pin 1, and modifying line 1 of the sketch to match your new analog pin should fix the problem. If this doesnât work properly, then your analog pin 0 is messed up. If this works properly, itâs probably a bad resistor that youâre trying to check, or a very big resistor, in which case you need to have a bigger R1 to get reliable values. This should give you a Vout of 5V (since none of the voltage is sunk to ground), and an R2 of 0 (which is actually infinity). You could test to see if itâs a problem with analog pin 0 by removing R2 from the circuit. Since electricity follows the path of least resistance, the point directly before R1 is Vin (5V on this setup), after R2 is 0V (connected to ground), and between R1 and R2 is Vout (the amount not being sunk to ground by R2). A voltage divider works by sinking a portion of the voltage in the circuit back to ground. After youâve got the LCD set up, connect the Ohm meter as shown above, and upload this program to the Arduino: include LiquidCrystal lcd (12, 11, 5, 4, 3, 2) int analogPin 0 int raw 0.That will show you how to connect everything. If it still doesnât work after that, I would conclude that you have a bad resistor or your analog pin 0 has somehow been damaged (the latter is really unlikely). First youâll want to read our tutorial on setting up an LCD display on the Arduino. These are the readings I got with a 200 Ohm âunknownâ resistor:įirst, check all your connections, and also verify that you have updated the sketch with the new resistance value for R1. After youâve got the LCD set up, connect the Ohm meter as shown above, and upload this program to the Arduino: #include First youâll want to read our tutorial on setting up an LCD display on the Arduino. One reader commented that they would like to display the resistance measurements on an LCD. Vout: is the voltage drop across your unknown resistor.R2: is the resistance of your unknown resistor in Ohms.When you open up the serial monitor youâll see the resistance values printed once per second. There will be two values, R2 and Vout. You can use any other analog pin though, just change the pin number in line 1, and wire the circuit accordingly. The program sets up analog pin A0 to read the voltage between the known resistor and the unknown resistor. Therefore, my line 5 should look like this: float R1 = 1000. In my case, Iâm using a known resistor with a value of 1K Ohms (1000 Ohms). Now, enter this code into the Arduino IDE and upload it to your board: int analogPin = 0 Ä®nter the value of your known resistor (in Ohms) on line 5 of the code above.
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