ROBOT . HEAD to TOE
Product User’s Manual –
Shield-Servo
c. 1st byte is combination of mode and servo motor channel. Servo motor channel is from
0-8 (decimal value). Select ‘0’ to activate all servo motor from channel 1 to 8.
0b
1
1
1
X
X
X
X
X
111
Mode for position and speed command
00000-01000
Servo motor channel, channel 1 to 8, represented by the decimal value
d. 2nd and 3rd byte combined provides 13 bit data of servo position, 0-8000. The resolution
of shield-servo is 0.25us. It will start from 0.5ms and increase the duty cycle of pulses
according to value of position. Thus, following formula show the duty cycle of pulse
generated.
.Duty cycle
= (resolution x servo position) + 0.5ms
= (0.25us x servo position) + 0.5ms
2nd Byte: 7 MSB of servo position
0b
0
X
X
X
X
X
X
X
12
11
10
9
8
7
6
3rd Byte: 6 LSB of servo position
0b
0
0
X
X
X
X
X
X
5
4
3
2
1
0
When both the 7 MSB(2nd Byte) + 6 LSB(3rd Byte) become 13 bit servo position
0b
X
X
X
X
X
X
X
X
X
X
X
X
X
12
11
10
9
8
7
6
5
4
3
2
1
0
e. 4th byte represents the speed of servo rotation. The speed is from 0-100 (Decimal value).
The higher value the faster servo will rotate to its position. Decimal value ‘1’ indicates
that the servo will run at slowest speed and decimal value ‘100’ will run at fastest speed.
However, value ‘0’ is special value. Value ‘0’ is the fastest speed, which is faster than
‘100’.
Servo motor speed 0-100
0b
0
X
X
X
X
X
X
X
Created by Cytron Technologies Sdn. Bhd. – All Rights Reserved
22
