When the SIM card adapter, which is usually plugged into a phone,
is plugged into a CCID reader instead, the CCID reader triggers
the reset line of the RST line and therefore a PIO interrupt.
The reader then waits for an ATR from the smartcard,
which should be send next.
Currently the smartcard insertion interrupt is always triggered,
but when checking in PIO_ISR which pin triggered the interrupt
often times DTXD is returned (the debug transmit line which is printing
debug messages at the moment..)
