Dynamic Text Label on Tkinter

Question

I researched a lot here in stack and google, I spent all night looking for a simple solution but I did not find, I saw some ways to solve but none worked for me until now.

Situation: I am creating a Python app using Tkinter to manage an Arduino board that controls some functions in a car such as ignition, headlights, battery states, sound etc. All the physical and installation part is ready.

On the Arduin, via serial connection with a netbook, I make a High, and it returns me a character to confirm the high in a rele

In python I get this character and modify a text in the label.

My problem is ae, I can read the character in the serial, but the label does not modify, in the code, this here specifically the situation described:

 status = StringVar()
 if iniciarconexao.receberDados == "e":
   status.set  ("Chave Ligou") 
 else:
   status.set ("Em Espera")     


 caixaestado = Label(Aplicativo, textvariable = status)
 caixaestado.pack (side="bottom")

Here are the links to the full code class code Serial connection with Arduine App Code

All Help and Welcome!