Francisco José Garzon, 52, was provisionally charged with 79 counts of reckless homicide after failing to brake in time ahead of a bend in the track, instead taking the curve at more than twice the appropriate speed.
Court officials said Garzon testified he thought he was on a different stretch of track, and by the time he realized where he was, it was too late to slow down from the 190 km/h speeds (118 mph) to 80 km/h.
The president of Spanish rail network administrator Adif said Garzon should have started braking about 4 km (2.5 miles) before the spot where the accident occurred.
Although Garzon has been charged in the deaths and injuries of the passengers, the investigation that will reveal his culpability is in its earliest stages. Investigators are working through the recordings in the train's black box to determine if mechanical failure played a role in the crash, or if it was a fatal oversight.
A judge has had the audio recording since Wednesday, the day of the crash, and is expected to examine them in full in court Tuesday. A few moments of audio from after the crash have been made public, including Garzon's lamentations.
"Poor travelers," he can be heard saying in Spanish. "I hope there are no dead because they will fall on my conscience."
Judge Luis Alaez revoked Garzon's passport and his license to drive a train for six months. Garzon was released from custody Sunday but must also appear in court weekly through February 2014.
Garzon has 30 years of experience driving trains, and has been on the route between Madrid and the port city Ferrol for a year.
A funeral mass for the dead was scheduled for Monday afternoon in Santiago de Compostela, the city where the deadly accident occurred. Spanish Prime Minister Mariano Rajoy, as well as several ministers and the king's children, Prince Felipe and Infanta Elena, are expected to attend.