Hi
I use arduino uno r3 .
Connected it to laptop n measured the potential difference between Tx pin and GND , multimeter read around 4.4 V.
But when I connected a resistor across it , it read around 2.4 V. were I was expecting 4.4 V itself.
Can someone help me figure it out please ....
What size resistor ( in Ohms) ?
And why would you hang a resistor on the Tx line?
The TX/RX pins of an Uno are already used by the USB<>Serial chip.
You shouldn't really use them for anything else.
Those two pins are normally HIGH.
You should measure 5volt on them, assuming your laptop and DMM are accurate.
Leo..