Control stepper motor with a sonar module

hello, i'm beginner arduino , i'm busy project want control stepper motor distance person sonar. i'm pretty close think problem stepper motor uses positive values go clockwise , negative values go counter clockwise. in code sonar measures in cm gives positive values stepper motor. how make numbers negative when person comes closer sonar module?

her code now:

code: [select]

#include <steppermotor.h>

steppermotor motor(8,9,10,11);

#define trigpin 6
#define echopin 12

 
void setup() {
 
serial.begin (9600);
motor.setstepduration(1);

pinmode(trigpin, output);
pinmode(echopin, input);
}
 
void loop() {
 
long duration, distance;
digitalwrite(trigpin, low);
delaymicroseconds(2);
 
digitalwrite(trigpin, high);

delaymicroseconds(10);
digitalwrite(trigpin, low);
 
duration = pulsein(echopin, high);
distance = (duration/2) / 29.1;
motor.step(distance);
}


i hope can me! in advance

quote from: bguchte on dec 13, 2017, 04:27 pm

how make numbers negative when person comes closer sonar module?

pick distance represents threshold want , subtract sonar measurement.

...r

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