Criticize Nnamdi Asomugha all you want. The newest 49er knows it's coming, be it for his age, his uneven play the past two seasons, whatever. He has an answer at the ready.

"There's a drive, there's a hunger inside of me that says, 'I know what I can do and I'm going to get it done,' " Asomugha said of his signing with the 49ers. "So, regardless of what others are saying or how others are feeling, I'm just going to make it happen."

Asomugha spoke Wednesday for the first time since he signed a one-year contract with San Francisco. He did so in the midst of escorting 20 high school students around the Cal campus as part of an annual event he conducts through his foundation.

Later in the day, Asomugha said he intended to sign the contract that he agreed to 24 hours earlier. He picked the 49ers over the New Orleans Saints less than a month after being released by the Philadelphia Eagles.

The 49ers intend to use him at cornerback, Asomugha said, even though he played safety for most of his collegiate career and at times during his eight years with the Raiders.

There isn't any doubt in Asomugha's mind that he still has the ability to be the kind of shutdown corner he was for most of his time with the Raiders, even though he is 31 and fresh from two seasons in which he struggled at times.

"I know what went wrong (in Philadelphia) and I know what I can do," Asomugha said. "It's not a see-what-happens-out-there sort of thing. It's going to happen."

Some speculated that the Eagles misused Asomugha, who flourished in a Raiders scheme that favored one-on-one coverage and where he used his long arms, physical style and sound technique to routinely shut down wide receivers.

Asomugha refused to place blame on the scheme, coaching or anything else. If anything, he said, his time with the Eagles will benefit him next season.

"I had a tough two years my first two in Oakland, and these two in Philly felt much longer than those two years," Asomugha said. "But, having been through that before, I know that I've got what it takes to turn it around … and put a stamp on something like no one would have ever imagined."

The 49ers return starting cornerbacks Carlos Rogers and Tarell Brown, as well as nickel back Chris Culliver. Asomugha will be given a chance to earn a starting spot.

"They're an organization that, from afar, you can tell that they got the pieces in place and they kind of know the structure and the game plan for winning," Asomugha said. "Then, when you come up close and you talk to the coaches and the players, the front-office people, you realize how serious they are about it and you kind of see how they've mapped it out. They made me a believer from the first time I met with them."

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