Error : incompatible types in assignment

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include "fichier.h"

char lireCaractere();
char* transMotEtoile (char* motEtoile, char essaiLettre, char* motSecret);
int nombCoups (char essaiLettre, char* motEtoile, int nbCoups);


int main(int argc, char *argv[])
{
char motEtoile[] = "*****";
char motSecret[] = "ROUGE";
char essaiLettre;
int nbCoups = 10;

 
  if (motEtoile != motSecret)     
  {  
   if (nbCoups != 0)
   {
	 while (motEtoile != motSecret)
     {
	 printf ("Bienvenue dans le Pendu\n\n\n");
	 printf ("Il vous reste %d coups a jouer\n", nbCoups = nombCoups (essaiLettre, motEtoile, nbCoups));
         motEtoile = transMotEtoile (motEtoile, essaiLettre, motSecret);  // l'erreur est là
	 printf ("Quel est le mot secret ? %s", motEtoile);
         printf ("Proposez une lettre : ");
	 essaiLettre = lireCaractere();
         printf ("\n\n");
	 }
   }  
  else
  printf ("Perdu !!");
	  

else
printf ("Gagne ! Le mot secret etait bien : %s", motSecret);

return 0;
}



char* transMotEtoile (char* motEtoile, char essaiLettre, char* motSecret)
{
int i = 0;
  
  while (i < 5)
  {
    if (essaiLettre == motSecret[i])
    {
    essaiLettre = motEtoile[i];
    i++;
	}
	
	else 
    i++;
   }

return motEtoile;
}
  
  
  
char lireCaractere() 
{ 
    char caractere = 0;
 
    caractere = getchar();
    caractere = toupper(caractere);
 
   
    while (getchar() != '\n') ;
 
    return caractere;
 
}


int nombCoups (char essaiLettre, char* motEtoile, int nbCoups)
{
int i = 0;  
  
  while (i < 5)
  {
    if (essaiLettre != motEtoile[i])
	i++;
	
	else
	{
	nbCoups--;
	i = 5;
	}
  }
return nbCoups;
}