It is unknown if he contributed anything to the Constitution itself.
However, he DID keep a diary of the goings-on among the Founding Fathers. Without that diary, the activities that the Founding Fathers performed would be a lost secret, since they decided to keep the convention confidential (even going so far as to board up the windows in blistering hot weather).
Who was at the constitutional convention
James Madison wrote the Constitution.
James Madison was at the age of 36 at the constitutional convention.
James madison
James Madison's role at the constitutional convention was to take notes of what every body said.
James Madison was the delegate who kept a notebook of daily events.
James Madison held accurate notes during the constitutional convention
James Madison
James Madison
Records were kept at the convention by James Madison.
if you are referring to the Constitutional convention Madison worked for the republican union he always envisioned.
=James Madison=