public OnPlayerKeyStateChange...
{
printf("Tecla: %d",newkeys);
...

#include <a_samp>
#define KEY_AIM 128

public OnFilterScriptInit()
{
    print("\n-----------------------------------------------");
    print(" Filterscript Todas as teclas SA-MP carregado.");
    print("-----------------------------------------------\n");
    return 1;
}

public OnPlayerKeyStateChange(playerid, newkeys, oldkeys)
{
    #define PRESSED(%0) \
        (((newkeys & (%0)) == (%0)) && ((oldkeys & (%0)) != (%0)))
    if(PRESSED ( KEY_ACTION )) GameTextForPlayer(playerid, "~g~ KEY ACTION", 3000, 5);
    if(PRESSED ( KEY_CROUCH )) GameTextForPlayer(playerid, "~g~ KEY CROUCH", 3000, 5);
    if(PRESSED ( KEY_FIRE )) GameTextForPlayer(playerid, "~g~ KEY FIRE", 3000, 5);
    if(PRESSED ( KEY_SPRINT )) GameTextForPlayer(playerid, "~g~ KEY SPRINT", 3000, 5);
    if(PRESSED ( KEY_SECONDARY_ATTACK )) GameTextForPlayer(playerid, "~g~ KEY SECONDARY ATTACK", 3000, 5);
    if(PRESSED ( KEY_JUMP )) GameTextForPlayer(playerid, "~g~ KEY JUMP", 3000, 5);
    if(PRESSED ( KEY_LOOK_RIGHT )) GameTextForPlayer(playerid, "~g~ KEY LOOK RIGHT", 3000, 5);
    if(PRESSED ( KEY_HANDBRAKE )) GameTextForPlayer(playerid, "~g~ KEY HANDBRAKE", 3000, 5);
    if(PRESSED ( KEY_LOOK_LEFT )) GameTextForPlayer(playerid, "~g~ KEY LOOK LEFT", 3000, 5);
    if(PRESSED ( KEY_SUBMISSION )) GameTextForPlayer(playerid, "~g~ KEY SUBMISSION", 3000, 5);
    if(PRESSED ( KEY_LOOK_BEHIND )) GameTextForPlayer(playerid, "~g~ KEY LOOK BEHIND", 3000, 5);
    if(PRESSED ( KEY_WALK )) GameTextForPlayer(playerid, "~g~ KEY WALK", 3000, 5);
    if(PRESSED ( KEY_AIM )) GameTextForPlayer(playerid, "~g~ KEY AIM", 3000, 5);
    if(PRESSED ( KEY_ANALOG_UP )) GameTextForPlayer(playerid, "~g~ KEY ANALOG UP", 3000, 5);
    if(PRESSED ( KEY_ANALOG_DOWN )) GameTextForPlayer(playerid, "~g~ KEY ANALOG DOWN", 3000, 5);
    if(PRESSED ( KEY_ANALOG_LEFT )) GameTextForPlayer(playerid, "~g~ KEY ANALOG LEFT", 3000, 5);
    if(PRESSED ( KEY_ANALOG_RIGHT )) GameTextForPlayer(playerid, "~g~  KEY ANALOG RIGHT", 3000, 5);
    if(PRESSED ( KEY_UP )) GameTextForPlayer(playerid, "~g~ KEY UP", 3000, 5);
    if(PRESSED ( KEY_DOWN )) GameTextForPlayer(playerid, "~g~ KEY DOWN", 3000, 5);
    if(PRESSED ( KEY_LEFT )) GameTextForPlayer(playerid, "~g~ KEY LEFT", 3000, 5);
    if(PRESSED ( KEY_RIGHT )) GameTextForPlayer(playerid, "~g~ KEY RIGHT", 3000, 5);
    return 1;
}