With the exception of the Avalon A7 which uses a RPI as its controller, there isn't any Bitcoin miner that is profitable and needs the RPI to control it. The Gridseed is mainly used to mine LTC and it isn't too profitable (maybe a couple pennies if you're lucky). Don't even think about mining BTC with it for profit- when it was released, the miner had below-average efficiency for its time. Now it's just an energy hog and mostly a collectible.

Additionally, if you are talking about Scrypt or other alt coin mining please move this out of Bitcoin mining speculation.