It looks like this is covered by article 34 of the criminal code you linked:
ARTICULO 34. - No son punibles:
[...]
- El que obrare en defensa propia o de sus derechos, siempre que concurrieren las siguientes circunstancias:
a) Agresión ilegítima;
b) Necesidad racional del medio empleado para impedirla o repelerla;
c) Falta de provocación suficiente por parte del que se defiende.
Se entenderá que concurren estas circunstancias respecto de aquel que
durante la noche rechazare el escalamiento o fractura de los cercados,
paredes o entradas de su casa, o departamento habitado o de sus
dependencias, cualquiera que sea el daño ocasionado al agresor.
Igualmente respecto de aquel que encontrare a un extraño dentro de su
hogar, siempre que haya resistencia;
English (my translation, no guarantees):
ARTICLE 34 - Not punished are:
[...]
- Someone who acts in self-defense or in defense of their rights, as long as the following circumstances apply:
a) illegitimate aggression
b) a rational need for the means used for preventing or repelling the aggression
c) a lack of sufficient provocation on the part of the defender
It is understood that these circumstances apply with respect to someone who during the night defends from a housebreaking or a breach of the enclosure, the walls or entrances to their home, or the home of their dependents, no matter what damage is caused to the attacker.
Reading these rules, which look quite similar to the law in most other countries, I'd say shooting an armed intruder would be covered.
It would probably already be covered under the general rules ( a) to c) ): There is an illegitimate aggression, and shooting is necessary for stopping the agressor, because no milder means is practical in the situation.
Additionally, the last paragraph would apply, which provides additional protection to someone defending their home, so even if a judge decided that normally shooting someone attacking with a knife is not necessary for protection, it would still be ok for home defence.
