A system for downhole communication, comprising: a downhole tool comprising: a downlink receiver to receive control information that controls operation of the downhole tool, the control information encoded in rotation of the downhole tool, the downlink receiver comprising: a rotation sensor configured to sense rotation of the downhole tool about a longitudinal axis of the downhole tool; and a decoder configured to: demarcate fields of the control information based on rotation state transitions sensed by the rotation sensor, wherein the rotation state transitions are transitions between a rotating state and a non-rotating state of the downhole tool; and decode a control value for controlling the downhole tool based on a duration of a field of the control information, wherein the control value is wholly encoded in the field and the field is encoded as a non-rotating state of the downhole tool; a command actuator that applies the control value to control operation of the downhole tool. a downhole tool comprising: a downlink receiver to receive control information that controls operation of the downhole tool, the control information encoded in rotation of the downhole tool, the downlink receiver comprising: a rotation sensor configured to sense rotation of the downhole tool about a longitudinal axis of the downhole tool; and a decoder configured to: demarcate fields of the control information based on rotation state transitions sensed by the rotation sensor, wherein the rotation state transitions are transitions between a rotating state and a non-rotating state of the downhole tool; and decode a control value for controlling the downhole tool based on a duration of a field of the control information, wherein the control value is wholly encoded in the field and the field is encoded as a non-rotating state of the downhole tool; a command actuator that applies the control value to control operation of the downhole tool. a downlink receiver to receive control information that controls operation of the downhole tool, the control information encoded in rotation of the downhole tool, the downlink receiver comprising: a rotation sensor configured to sense rotation of the downhole tool about a longitudinal axis of the downhole tool; and a decoder configured to: demarcate fields of the control information based on rotation state transitions sensed by the rotation sensor, wherein the rotation state transitions are transitions between a rotating state and a non-rotating state of the downhole tool; and decode a control value for controlling the downhole tool based on a duration of a field of the control information, wherein the control value is wholly encoded in the field and the field is encoded as a non-rotating state of the downhole tool; a rotation sensor configured to sense rotation of the downhole tool about a longitudinal axis of the downhole tool; and a decoder configured to: demarcate fields of the control information based on rotation state transitions sensed by the rotation sensor, wherein the rotation state transitions are transitions between a rotating state and a non-rotating state of the downhole tool; and decode a control value for controlling the downhole tool based on a duration of a field of the control information, wherein the control value is wholly encoded in the field and the field is encoded as a non-rotating state of the downhole tool; demarcate fields of the control information based on rotation state transitions sensed by the rotation sensor, wherein the rotation state transitions are transitions between a rotating state and a non-rotating state of the downhole tool; and decode a control value for controlling the downhole tool based on a duration of a field of the control information, wherein the control value is wholly encoded in the field and the field is encoded as a non-rotating state of the downhole tool; a command actuator that applies the control value to control operation of the downhole tool.