Hardware Reference
In-Depth Information
Figure 4-1. Driving a servo motor with the 3.3 V power supply
The code for controlling the servo motor is in
servoMotor.js
, shown in
Example 4-1
.
Example 4-1. Code for driving a servo motor (servoMotor.js)
#!/usr/bin/env node
// Drive a simple servo motor back and forth
var
b
=
require
(
'bonescript'
);
var
motor
=
'P9_21'
,
// Pin to control servo
freq
=
50
,
// Servo frequency (20 ms)
min
=
0.8
,
// Smallest angle (in ms)
max
=
2.5
,
// Largest angle (in ms)
ms
=
250
,
// How often to change position, in ms
pos
=
1.5
,
// Current position, about middle
step
=
0.1
;
// Step size to next position
console
.
log
(
'Hit ^C to stop'
);
b
.
pinMode
(
motor
,
b
.
ANALOG_OUTPUT
,
6
,
0
,
0
,
doInterval
);
function
doInterval
(
x
) {
if
(
x
.
err
) {
console
.
log
(
'x.err = '
+
x
.
err
);
return
;
}
timer
=
setInterval
(
sweep
,
ms
);
}
move
(
pos
);
// Start in the middle
// Sweep from min to max position and back again
