hi,



Yes and no.
Indeed, you may use one-way communication for sending data from master to slave via MOSI and SCK lines. For SPI there are no hardware handshake except /SS pin to select slave device.

As about MISO pin as general IO one so the answer is "no". Probably the MISO pin might be used as input port pin for master device although I would not use alternative function utilized pin for other purposes.
But for slave device the pin has been drove with SPI even not utilized, so it can be used neither as input nor as output general port pin.
By the way, I have seen some tricks about this pin of slave but I do not suggest them due ugly programming style.

For last but not least:
- if you have no enough code memory -> you selected wrong derivative;
- if you have no enough pins -> you selected wrong derivative or made not good schematic.
In short: avoid any tricks and you lost their [undefined] side-effects.

Regards,
Oleg