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I am trying to build a walking robot for my son's school project
The whole point of an education is so that your son learns and shows off what he is capable of, not what you created for him. Anyway...
The SSC-32 is a servo motor controller, and you can connect a Bluetooth module directly to the Tx and Rx pins without the need for a separate microcontroller. You only need the one SSC-32. The issue is that the computer will need to be sending the information / walking algorithm to the SSC-32 since it has no onboard intelligence (the computer becomes the "brain").
Hope this helps,