I have a Arduino-Mega and the tft seeedstudio 2.8.
And the library for Arduino
I try to make a volt-amp meter 0-300v 100ma
All is working wel, only the display gives a question mark by reading the output off a sensorValue.
This is an example.
int sensorValue = analogRead(A6);
float voltage_string = sensorValue * (5.0 / 1023.0);
The reading by Serialprint is ok
Can anyone help me.