9 years, 8 months ago.

AnalogIn::read_u16 function returns 0..4095. (NUCLEO-F103RB)

When I tried the following code on NUCLEO-F103RB, read_u16 function returned values between 0 and 4095.

1. include "mbed.h"

AnalogIn adin(A0);

int main() { while(1) { printf("%d %f\n",adin.read_u16(),adin.read()); } while } main

However, the API document on the read_u16 function says "16-bit unsigned short representing the current input voltage, normalised to a 16-bit value." So I expected that I got values between 0 and 0xfff0(65520). Is this a bug in the API library for NUCLEO-F103RB?

In addition, the sample program provided by STMicro that shows how to use AnalogIn is as follows. (You can get this sample at https://mbed.org/teams/ST/code/Nucleo_read_analog_value/?platform=ST-Nucleo-F103RB .)

1. include "mbed.h"

AnalogIn analog_value(A0);

DigitalOut myled(LED1);

Calculate the corresponding acquisition measure for a given value in mV

1. define MV(x) ((0xFFF*x)/3300)

int main() { while(1) { uint16_t meas = analog_value.read_u16(); Converts and read the analog input value if (meas > MV(1000)) { If the value is greater than 1000 mV toggle the LED myled = !myled; } wait(0.2); 200 ms } }

The line

1. define MV(x) ((0xFFF*x)/3300)

implies that the programmer who ported mbed library to Nucreo family thinks the read_u16 function returns a raw value of an A/D conversion, I guess. Is this right?

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