issue with ESC calibration and control

My servo doesn’t run in reverse.

I tried calibration but still it doesn’t work with any pwm signal below 90.

I am using rc car from hobbyking

My code#include <Servo.h>

Servo steer;
Servo accel;

void setup()
{
Serial.begin(9600);
accel.attach(10);
steer.attach(11);
accel.write(180);
delay(1200);
accel.write(0);
delay(1200);
accel.write(90);
delay(1200);

}

void loop()
{
accel.write(84);
delay(1200);

}
any value below 90 and above 175 the car doesn’t run

#include <Servo.h>

Servo steer;
Servo accel;

void setup()
{
Serial.begin(9600);
accel.attach(10);
steer.attach(11);
accel.write(180);
delay(1200);
accel.write(0);
delay(1200);
accel.write(90);
delay(1200);

}

void loop()
{
accel.write(84);
delay(1200);

}
This is a basic code for calibration i am using.

Now when i try to write any value below 90 the servo does’t work. only with values greater than 90 the servo works.

angshumannitb:
Now when i try to write any value below 90 the servo doesn't work. only with values greater than 90 the servo works.

I think that's normal right?

Like.... for typical servos, the 'centre' (mid position) occurs (usually) when pulse width is 1500 microsecond. Well..... a 1500 microsecond pulse width out of a total cycle of 20000 microseconds or something.

If values are too 'small' or too 'large', then the servo won't go to the position you want it to, so we usually need to run some test code to find out what range of pulse width values the servo will properly respond to.