need more pins

i need more digital pins, at least 25 so what to do?

(deleted)

Use a Mega.
Or shift registers.
Or an I2C I/O extender.
Or… lots of other ways.
Depends really on what it is you want to do.
Which you didn’t tell us.

Pick up one of Crossroad's Bobuinos, ATMega1284P Duemilanova-style . – 32 Programmable I/O Lines – 128KBytes of In-System Self-programmable Flash program memory – 4KBytes EEPROM – 16KBytes Internal SRAM

http://www.crossroadsfencing.com/BobuinoRev17/

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If you end up with a Mega (as your post isn’t clear if you need 45 IO), I also offer Mega Screw shields to securely connect all those wires

There is a shield called I/O Expander Shield for Arduino/pcDuino (MCP23017 ). you can buy it for about ten dollars from e bay( link down below). It gives you 28 digital pins and 12 analog pins you can use the analogs for digital input/output too. (update: apparently you dont have additional analog pins, sorry

eBay link: http://www.ebay.com/itm/SALE-LinkSprite-I-O-Expander-Shield-MCP23017-for-Arduino-pcDuino-/282174290755?hash=item41b2e5fb43:g:yb4AAOSwOyJX15RE