Resuelto
int leds;
bool estadoled = LOW;
unsigned long tinicial = 0;
unsigned long intervalo = 1000;
void setup() {
Serial.begin(9600);
for(leds=8; leds<=12; leds++){
pinMode(leds, OUTPUT);
}
leds = 8;
tinicial = 0;
}
void loop() {
if (millis() - tinicial >= intervalo){
digitalWrite (leds, !digitalRead(leds));
Serial.println(leds);
if(leds++ == 12)
leds = 8;
tinicial = millis();
}
}