the TMP36 temperature sensor) – the calculated value will be wrong. This may sound trivial, however if you’re using a sensor that returns a value as a voltage (e.g. For example, if your voltage is 4.8V – the analogRead() range of 0~1023 will relate to 0~4.8V and not 0~5V. If you don’t have any option, you can use some maths in your sketch to compensate for the drop in voltage. This is important as the accuracy of any analogRead() values will be affected by not having a true 5 V. Then after that goes through the power regulator circuit you’ll have a nice 5V, for example the image. So if you’re gunning for accuracy, power your board from an external power supply via the DC socket or Vin pin – such as 9V DC. ![]() Some boards will return as low as 4.8 V, some higher but still below 5V. This can easily be demonstrated by connecting an Arduino Uno to USB and putting a multimeter set to measure voltage across the 5V and GND pins. For example, if you have a typical Arduino Uno board and run it from the USB socket – sure, there is 5V available to the board from the USB socket on your computer or hub – but the voltage is reduced slightly as the current winds around the circuit to the microcontroller – or the USB source just isn’t up to scratch. The value returned from analogRead() would be between zero an 1023, with zero representing zero volts and 1023 representing the operating voltage of the Arduino board in use.Īnd when we say the operating voltage – this is the voltage available to the Arduino after the power supply circuitry. ![]() You may recall that you can use the Arduino analogRead() function to measure the voltage of an electrical current from sensors and so on using one of the analogue input pins.
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