You can set keyframes with Stepped interpolation or change keyframes to use Stepped interpolation.

To set keyframes with Stepped interpolation:

1. In the Key Controls window, select Stepped from the Type menu.
   

   Key Controls A. Stepped interpolation selected in the Type menu

2. Set keyframes (see Setting keyframes). The keyframes you set have Stepped interpolation until you select a different type of interpolation.

To change the interpolation of a keyframe to Stepped:

1. In the FCurves window, select the keyframe or keyframes whose interpolation you want to change.
2. In the Tangent options, select the Stepped interpolation type.
   

   FCurves window (detail) in Classic Mode A. Stepped interpolation type selected for the keyframe selection B. Step and Step Next mode

3. Select Step mode or Step Next mode, which determine whether the interpolation maintains the value of the current or next keyframe. See Stepped interpolation for more information.