[avr-chat] Comparisson with negative values

[John]

My application is just a development from largedemo.

I have two potentiometers with the idea of developing a controller.

These are named reference and feedback.

 

volatile uint16_t reference;

volatile uint16_t feedback;

volatile uint16_t error;

 

// this works

 

if (reference > feedback) set_pwm(pwm + 1);

if (reference < feedback) set_pwm(pwm - 1);

 

// this does not work

 

error = reference - feedback;

 

if (error > 0) set_pwm(pwm + 1);

if (error < 0) set_pwm(pwm -1);

 

In the later case error can take positive or negative values.

In the former case only positive values are involved.

 

Would someone be as good as to send me the correct syntax

for a comparisson with negative numbers.

 

 

John