(a) Probation.

After conviction of an offense the defendant may be placed on probation as provided by law.

(b) Revocation or Modification of Probation.

The court shall not revoke or modify probation except (1) after a hearing in which the defendant shall be present and apprised of the grounds on which such action is proposed, or (2) upon stipulation of the parties. The defendant is entitled to be represented by a lawyer and may be released pursuant to rule 3.2 pending such hearing. A lawyer shall be appointed for a defendant financially unable to obtain one.