Product Documentation

Motor 1 and 2 current

A guide reading of the average current through the motor is available. It reads approx ten times the

number of Amps (25 at 2.5A).

Software Revision number

Responds with the revision number of the software in the modules PIC18F2321 controller - currently 1

at the time of writing.

Acceleration Rate

If you require a controlled acceleration period for the attached motors to reach there ultimate speed, the

MD49 has the ability to provide this. It works by using a sent acceleration value and incrementing the

power by that value. Changing between the current speed of the motors and the new speed. So if the

motors were traveling at full speed in the forward direction (255) and were instructed to move at full

speed in reverse (0), there would be 255 steps with an acceleration register value of 1, but 128 for a

value of 2. The default acceleration value is 5, meaning the speed is changed from full forward to full

reverse in 0.816 seconds. The WRITE ACCELERATION command will accept values of 1 up to 10

which equates to a period of only 0.416 seconds to travel from full speed in one direction to full speed

in the opposite direction.

So to calculate the time (in seconds) for the acceleration to complete :

if new speed > current speed

steps = (new speed - current speed) / acceleration register

if new speed < current speed

steps = (current speed - new speed) / acceleration register

time = steps * 16ms

For example :

Acceleration

Time/step Current speed New speed Steps Acceleration time

1 16ms 0 255 255 4.08s

2 16ms 127 255 64 1.024s

3 16ms 80 0 27 0.432s

5 (default) 16ms 0 255 51 0.816s

10 16ms 255 0 26 0.416s

Mode

The mode command changes the way the speed/turn values are used. The options being:

0, (Default Setting) If a value of 0 is written then the speed registers is literal speeds in the range of 0

(Full Reverse) 128 (Stop) 255 (Full Forward).

1, Mode 1 is similar to Mode 0, except that the speed values are interpreted as signed values. The

range being -128 (Full Reverse) 0 (Stop) 127 (Full Forward).

2, Writing a value of 2 to the mode will make speed1 control both motors speed, and speed2

becomes the turn value.

Data is in the range of 0 (Full Reverse) 128 (Stop) 255 (Full Forward).