User Manual

Note that the servo positions are specified in units of 0.25 μs, so a value of 4000 corresponds to 1 ms.

The text after the # is a comment; it does not get programmed on to the device, but it can be useful for

making notes about how the program works. Good comments are essential for complicated programs.

It is important to remember the DELAY commands; without these, the script will not wait at all between

servo commands, running the loop hundreds of times per second.

Compressing the sequence

The program above takes 58 bytes of program space: 11 bytes for each servo position and 3 for

the loop. At this rate, we could store up to 92 servo positions in the 1024-byte memory of the Micro

Maestro, or 744 servo positions in the 8192-byte memory of the Mini Maestros. To get the most out of

the limited memory, there are a variety of ways to compress the program. Most important is to make

use of subroutines. For example, since we repeat the instructions “0 servo 500 delay” several times,

we can move them into a subroutine to save space. At the same time, this simplifies the code and

makes it easier to make future modifications, such as changing the speed of the entire sequence.

Using the subroutine brings the script down to 31 bytes: 4 per position and 11 bytes of overhead for

the loop and to define FRAME. We can go further: inspecting the compiled code shows that putting

each number on the stack requires 3 bytes: one byte as a command, and two for the two-byte number.

Numbers from 0 to 255 can be loaded onto the stack with just two bytes. Suppose in our application

we do not need the full 0.25 μs resolution of the device, since all of our settings are multiples of 100.

Then we can use smaller numbers to save another byte:

# Move servo 0 to five different positions, in a loop.

begin

4000

frame

5000

frame

6000

frame

7000

frame

8000

frame

repeat

sub frame

0 servo

500 delay

return

6. The Maestro Scripting Language Page 79 of 102