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   This directory contains the device entries for the Dual DC Motor
Controller.


HARDWARE
   This peripheral controls the speed and direction of two brushed
DC motors designated as '0' and '1'.  
   The motor speed signals are pulse width modulated (PWM) signals
with a programmable duty cycle between 0 and 100 percent and a
programmable PWM frequency.


DEVICE NODES
The device interfaces to the dual DC motor controller offer
independent direction and speed for each of the two motors.
The PWM frequency is common to both motors.

.../mode0, .../mode1
   The mode of operation for the motor.  The mode is encoded
as a single character with the codes assigned as follows:
     b -- brake  (power on default)
     f -- forward
     r -- reverse
     c -- coast

.../speed0, .../speed1
   The PWM 'ON' time as a percentage in the range 0 percent
to 100 percent.   The speed resolution is 10 bits for PWM
frequencies below 20 KHz.  The speed resolution is 8 bits for
a PWM frequency of 78 KHz.

.../PWMfrequency
   The frequency of the speed PWM signal in Hertz.  The driver
tries to assign a frequency as close as possible to the one
specified.  For example, a requested frequency of 12510 Hertz
might result in an actual PWM frequency of 12500 Hertz.  The
PWM frequency is the same for both motors.

.../slow_start0, .../slow_start1
   The acceleration curve as a list of ten comma separated integers
representing the time (in milliseconds) between each 10 percent
increase from 0 to 100 percent ON time.  For example, the following
specifies a slow start that takes half a second to get to 50 percent
power and three-quarters of a second to get from zero to full power:
    100,100,100,100,100,50,50,50,50,50
The default value for slow_start is off to full power in
zero milliseconds.  That is, the default is to turn off slow
start.

.../slow_stop0, .../slow_stop1
  The deceleration curve as a list of ten comma separated integers
representing the time (in milliseconds) between each 10 percent
decrease from 100 to 0 percent ON time.  For example, the following
specifies a slow stop that takes half a second to get to 50% power
and three-quarters of a second to get from full power to zero:
        100,100,100,100,100,50,50,50,50,50
The default value for slow_stop is full on to full off in
zero milliseconds.  That is, the default is to turn off slow
stop.

.../watchdog
    As a safety feature, the driver and FPGA hardware can turn
both motors off if there is no speed or direction update from
the controlling software within the specified time.  The time
is specified in milliseconds and has a maximum value of 1500
milliseconds.  The resolution of the watchdog timer is 100
milliseconds, and a value of zero turns off the watchdog timer.
The default value is 300 milliseconds.