How about:
void loop() {
digitalWrite(LED_BUILTIN, HIGH);
digitalWrite(PB7, HIGH);
delay(1000);
digitalWrite(LED_BUILTIN, LOW);
digitalWrite(PB7, LOW);
delay(1000);
}
How about:
void loop() {
digitalWrite(LED_BUILTIN, HIGH);
digitalWrite(PB7, HIGH);
delay(1000);
digitalWrite(LED_BUILTIN, LOW);
digitalWrite(PB7, LOW);
delay(1000);
}