How to fill form fields since HTML

Question

I have been looking for information on the web about how set values in forms of django but it has been really difficult. I need to put "Inicio" in the field "Origen_del_Circuito" after pushing the button, I have this code:

Forms.py

class CargaElectricaForm(forms.Form):
        
    Circuito=forms.CharField(label='Circuito', max_length=200)
    Origen_del_Circuito=forms.CharField(label='Origen del Circuito', max_length=200 )

views.py

def bajatension(request):
    if request.method=="POST":
        form=CargaElectricaForm(request.POST)
        
        if form.is_valid():            
            #form.save()
            c="Inicio"                       
            return render (request, 'SizingWires/lowvoltage.html',{'form':form,'c':c})
    else:
        form=CargaElectricaForm()
        return render (request, 'SizingWires/lowvoltage.html',{'form':form})**

lowvoltage.html

<form method="post" >
     {% csrf_token %}
     <table>
     {{form.as_table}}
     </table>
     <input type="submit"> Calculator</button>
     <input type="text" value="{{c}}">
          </form>

It doesn't work because it creates a new input and I need to use the field "Origen_del_Circuito". How can I access to the fields of my form since HTML (file lowvoltage.html) to put the value of "c"? I know the method "initial" however I need to put the value after of pushing the button.