Cannot read serial messages using AEK-MCU-C4MLT1 and SPC5 studio

Question

I am currently working on a project where I am using the serial communication.

I am using an AEK-MCU-C4MLT1, with SPC5 studio on a windows PC.

In particular, I am capable to transmit data but not to receive data.

I tried also enabling the interrupt, either for the transmission and the reception, and I found out that the program enters the interrupt each time I call the function sd_lld_read, even if I send no data externally (from docklight).

By sending data from docklight, and looking at the rx_buffer I am not able to read anything.

I attach the relevant part of the code here:

int main(void) {

    /* Initialization of all the imported components in the order specified in
     the application wizard. The function is generated automatically.*/
    componentsInit();

    /* Uncomment the below routine to Enable Interrupts. */
    irqIsrEnable();
    sd_lld_start(&SD1,&serial_config_UART);

    sd_lld_read(&SD1, (uint8_t*)aux_rx, 1000);

    memset(aux_rx,0,sizeof(aux_rx));
    /* Application main loop.*/
    for ( ; ; )
    {
        sprintf(aux_tx,"ATE1\r\n");
        sd_lld_write(&SD1,(uint8_t *)aux_tx, (uint16_t)(strlen(aux_tx)));
        osalThreadDelayMilliseconds(5000);
}

void rxreceive(SerialDriver *sdp)
{
    (void)sdp;
}

void txreceive(SerialDriver *sdp)
{
    (void)sdp;
    pal_togglepad(PORT_F,10);
}

Do you have any idea of what do I have to do in order to receive data and correctly read data? Do you know if I have to call another function in the interrupt?