12
2.3 Analog interface
Analog interface mode is the simplest interface, and it is often used to be tested whether drive circuit
is good or not. Compared to above two interfaces, there is only one detail need to be noted, if the
user is using a potentiometer to regulate motor speed, the direction mode is bidirectional, and require
potentiometer mechanical location highly symmetric (that is in the mechanical rotating range
potentiometer could reach, a half for positive running, another half opposite-direction running), then
at the output terminal of potentiometer, recommends using voltage followed device output, certainly,
the user can also use AVR to create PWM + filtering circuit, or use dedicated DAC chip to achieve
controllable output voltage signal. In addition, both in open-loop or closed-loop control mode, the
relationship between input voltage value and motor speed are described as the figure below.
Open-loop control mode
Connect the cable, as shown in the figure (Connect one circle if you only control one motor):
