Trying to stuff this sketch in Atmega8.

You need to reduce the size of the sketch at 1022 bytes (minimum), but I do not know how

# include & lt; arduino.h & gt;
#Include "servosmooth.h" // https://github.com/alexGyver/gyverlibs/tree/master/Servosmooth
#Define Engine_pin 11.
#Define Servo_Pin 9.
#Define Reverse_Pin 5.
Long Last_m_time = 0;
int ENGINE_PWM = 0;
int is_reverse_engine = 0;
int servo_angle = 90;
SERVOSMOOTH STEERING;
void setup ()
{
 Serial.begin (9600);
 Serial.settimeout (20);
 Pinmode (Engine_Pin, Output);
 Pinmode (SERVO_PIN, OUTPUT);
 Pinmode (Reverse_Pin, Output);
 Steering.attach (SERVO_PIN);
 Steering.Setspeed (130);
 Steering.Setaccel (0.1);
}
String GetValue (String Data, Char Separator, Int Index)
{
 INT FOUND = 0;
 INT STRINDEX [] = {0, -1};
 int maxindex = data.length () - 1;
 For (int i = 0; i & lt; = maxindex & amp; & amp; found & lt; = index; i ++)
 {
  if (data.charat (i) == separator || i == maxindex)
  {
   Found ++;
   STRINDEX [0] = strindex [1] + 1;
   Strindex [1] = (i == Maxindex)? I + 1: I;
  }
 }
 RETURN FOUND & GT; index? Data.Substring (Strindex [0], Strindex [1]): "";
}
Void Decode_Message (String Data)
{
 // Rowes 90: 120: 0
 SERVO_ANGLE = GETVALUE (DATA, ':', 0) .TOINT ();
 Engine_pwm = getValue (Data, ':', 1) .TOINT ();
 is_reverse_engine = getValue (Data, ':', 2) .TOINT ();
}
Void Reset_vehicle ()
{
 ENGINE_PWM = 0;
 is_reverse_engine = 0;
 SERVO_ANGE = 90;
}
Void Check_Connection ()
{
 If ((Millis () - Last_m_Time) & gt; 700)
 {
  RESET_VEHICLE ();
 }
}
void loop ()
{
 String Data = Serial.ReadStringuntil ('\ n');
 if (data.length () & gt; 0)
 {
  Last_m_time = Millis ();
  Decode_Message (DATA);
 }
 steering.settargetdeg (SERVO_ANGE);
 AnalogWrite (Engine_pin, Engine_PWM);
 DigitalWrite (Reverse_Pin, is_reverse_engine);
 check_connection ();
 steering.tick ();
}

UPD:

What I could do (now need to reduce another 824 byte):

# include & lt; arduino.h & gt;
#Include "servosmooth.h" // https://github.com/alexGyver/gyverlibs/tree/master/Servosmooth
#Define Engine_pin 11.
#Define Servo_Pin 9.
#Define Reverse_Pin 5.
uint32_t last_m_time = 0;
BYTE ENGINE_PWM = 0;
byte is_reverse_engine = 0;
BYTE SERVO_ANGLE = 90;
SERVOSMOOTH STEERING;
void setup ()
{
 Serial.begin (9600);
 Serial.settimeout (20);
 Pinmode (Engine_Pin, Output);
 Pinmode (SERVO_PIN, OUTPUT);
 Pinmode (Reverse_Pin, Output);
 Steering.attach (SERVO_PIN);
 Steering.Setspeed (130);
 Steering.Setaccel (0.1);
}
String GetValue (String & Amp; Data, Char Separator, UINT8_T INDEX)
{
 INT FOUND = 0;
 INT STRINDEX [] = {0, -1};
 uint8_t maxindex = data.length () - 1;
 For (uint8_t i = 0; i & lt; = maxindex & amp; & amp; found & lt; = index; i ++)
 {
  if (data.charat (i) == separator || i == maxindex)
  {
   Found ++;
   STRINDEX [0] = strindex [1] + 1;
   Strindex [1] = (i == Maxindex)? I + 1: I;
  }
 }
 RETURN FOUND & GT; index? Data.Substring (Strindex [0], Strindex [1]): "";
}
Void Decode_Message (String & Amp; DATA)
{
 SERVO_ANGLE = GETVALUE (DATA, ':', 0) .TOINT ();
 Engine_pwm = getValue (Data, ':', 1) .TOINT ();
 is_reverse_engine = getValue (Data, ':', 2) .TOINT ();
}
Void Reset_vehicle ()
{
 ENGINE_PWM = 0;
 is_reverse_engine = 0;
 SERVO_ANGE = 90;
}
Void Check_Connection ()
{
 If ((Millis () - Last_m_Time) & gt; 700)
 {
  RESET_VEHICLE ();
 }
}
void loop ()
{
 String Data = Serial.ReadStringuntil ('\ n');
 if (data.length () & gt; 0)
 {
  Last_m_time = Millis ();
  Decode_Message (DATA);
 }
 steering.settargetdeg (SERVO_ANGE);
 AnalogWrite (Engine_pin, Engine_PWM);
 DigitalWrite (Reverse_Pin, is_reverse_engine);
 check_connection ();
 steering.tick ();
}

Answer 1

Hyver library in principle does not fit atmega8.

In order to make sure to try to compile the sketch that does not do anything, simply connects libraries:

# include & lt; arduino.h & gt;
#Include "servosmooth.h" // https://github.com/alexGyver/gyverlibs/tree/master/Servosmooth
#Define Engine_pin 11.
#Define Servo_Pin 9.
#Define Reverse_Pin 5.
SERVOSMOOTH STEERING;
void setup ()
{
  Serial.begin (9600);
  Serial.settimeout (20);
  Pinmode (Engine_Pin, Output);
  Pinmode (SERVO_PIN, OUTPUT);
  Pinmode (Reverse_Pin, Output);
  Steering.attach (SERVO_PIN);
  Steering.Setspeed (130);
  Steering.Setaccel (0.1);
}
void loop ()
{
}

Possible options:

1. Choose more “bold” chip.
2. Do not use libraries, but to implement the desired logic yourself.