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9 years, 11 months ago.
FRDM-KL25Z AnalogIn wrong Values
Hi team,
I'm just starting and wanted to do a very simple test and read the voltage from an analog input pin (PTB2). Therefore I have a power-source with 3V directly connected to it. So I would expect a value around 0.9 or so (as 3.3V is maximum = 1).
Unfortunately the value I read is fluctuating basically between 0 and 1 and is never static. Even when nothing is connected to the board this program is reading random values around 0.1 - 0.2V Is there a simple mistake I do?
My code:
Example
#include "mbed.h" Serial pc(USBTX, USBRX); // tx, rx PwmOut led(LED_RED); AnalogIn voltage(PTB2); int main() { pc.printf("Meassuring the input voltage"); while(true) { printf("Voltage (%f)\n", voltage.read()); wait(0.2); } }
Best Regards Kilian
1 Answer
9 years, 11 months ago.
please use <<code>> <</code>>
tags around your code when posting to keep it readable.
Do you have a common ground pin? Seems that 0.1V is way off the expected value, but maybe there is a lot of noise on the analog power source, have you checked with a scope.