Unexpected behaviour of an iexternal interrupt function, dspic33f

Question

The project I'm desperatly trying to finish is rather simple in term of microcontroller programming. The dspic33fj128mc802 I use basically has to do 3 things:

• receive data via UART and convert it into PWM signals for servomotors

• regularly wake up its ADC to check a battery level

• change its baudrate working values when fed an external interrupt.

It's the last point that causes issue. In my circuit I have a switch. One position corresponds to a baudrate value, the other one to a second value. I didn't find any documentation on how to trigger an interrupt on any voltage level change, so I use rising edge and falling edge trigger in combination with checking the current state of the pin I chose for my interrupt.

Furthemore, I have two other interrupt functions in my code, one for UART reception, and the second one is a timer interrupt to wake up the ADC periodically. Interrupt priorities are the following: UART -> 1, Timer -> 2, External Interrupt -> 6 (any number above 2 really).

Here is my interrupt code:

void __attribute__((interrupt, auto_psv)) _INT0Interrupt( void ) 
{   
IEC0bits.INT0IE = 0; // disable INT0 interrupt

if(IFS0bits.INT0IF){ 
    if (PORTBbits.RB7 == 1){ //if pin at high logic level
        INTCON2bits.INT0EP = 1; //falling edge trigger
        LATAbits.LATA0 = 1;
        U1BRG = 23;
    }
    else{ //if pin at low logic level
        INTCON2bits.INT0EP = 0; //rising edge trigger
        LATAbits.LATA0 = 0;
        U1BRG = 1;
    }
}
IFS0bits.INT0IF = 0; //clear INT0 flag
IEC0bits.INT0IE = 1; // enable INT0 interrupt

}

The weird behaviour now -> When pulling the pin to low, the baudrate is set at the right value, the UART commmunication works perfectly. When pulled to high, the previous communication doesn't work anymore, proof that the baudrate has changed, but setting the new communication at that new baudrate doesn't work either. The LED status change works fine as well.

It is to be noted that all the different apsects of this project have been tested multiple times, each section works well, only adding this External Interrupt made the whole thing crash. The microcontroller works fine, my baudrate values are good, my circuit has been tested and has no issues.... I jst think I don't know how to properly use an external interrupt.