Texas Instruments Stellaris, Руководство пользователя

Страница: 14 / 45

User Interfaces
14 November 4, 2009
The on-board user interface can operate in two modes: Speed mode and Position mode. In Speed
mode, the motor runs continuously at a speed and direction that can be controlled by the user. In
Position mode, the motor runs to a position controlled by the user. The starting mode is Speed
mode.
The following on-board controls are available:
„
Reset button: Restarts the stepper RDK software. The software enters Speed mode.
„
User button: Switches between on-board UI modes, and starts and stops the motor. To change
modes, hold down the user button for five seconds. To start and stop the motor, press and
release the button. If a fault occurs (the status LED is blinking rapidly), press and hold the user
button for five seconds to clear the fault. Doing this will not change modes.
„
Potentiometer knob: The potentiometer is used to adjust the speed of the motor when Speed
mode is used, and is used to adjust the position of the motor when Position mode is used.
„
Mode LED: Informs the user which mode is selected by blinking a pattern.
„
Status LED: Indicates the motor speed by blink rate. Also indicates a fault with rapid blinking.
Speed Mode
Upon entering Speed mode, the mode LED blinks one time. This is the default when the board is
first powered, or after the reset button is pressed. To enter Speed mode from Position mode, press
and hold the user button for five seconds, until the mode LED blinks one time.
In Speed mode, the motor runs at a speed that is controlled by the position of the potentiometer
knob. Upon entering Speed mode, the motor is stopped. To start the motor running, press the user
button. The motor begins running in the forward direction. Forward is designated as clockwise.
Use the user button to start and stop the motor. Each time the button is pressed, the motor either
starts running if it is stopped, or stops if it is already running. Each time the motor starts running, it
runs in the opposite direction from the previous time.
The potentiometer knob is used to change the motor speed. The motor runs at a minimum speed
of 10 steps/second when the knob is turned all the way to the left (counterclockwise), and at a
maximum of about 1000 steps/second when the knob is turned all the way to the right (clockwise).
The status LED blinks at a rate that varies according to the motor speed.
Caution – Do not leave the motor running for long periods of time. If the motor is not attached to
a heat sink, the case can get very hot, especially if a high drive current is used.
Position Mode
Upon entering Position mode, the mode LED blinks twice. To enter Position mode from Speed
mode, press and hold the user button for five seconds, until the mode LED blinks two times.
In Position mode, the motor always runs to a position that is determined by the position of the
potentiometer. When the potentiometer is moved, the motor moves to the new position. The input
from the potentiometer is scaled so that the motor turns one revolution (at 200 steps/revolution) as
the knob is turned from one extreme to the other. The motor turns in the same direction as the
potentiometer knob.
In Position mode, the motor is enabled by default and turns as soon as the knob is turned. If the
button is pressed, then the motor is disabled and does not run when the knob is turned. The motor
can be re-enabled by pressing the user button again.