The 19-year-old moved to Villa last summer after two goals in 28 appearances for League One Northampton.
"Caleb is going to complement the squad very well," said Martindale.
"He comes with quite a big reputation from the staff at Aston Villa.
"He can play anywhere across the front three and will give us different options in the forthcoming games as he offers a very different skill set to what we have at the club already."
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