Manual

Option 4: Analog Diff-
Drive Mix
Diff-Drive Mix is used for robots
and vehicles with tank style steering
using two SyRens. Two analog
signals are fed into S1 and S2. The
signal fed into S1 is the forwards/back command (0v full reverse, 5v full forward, 2.5v stop) and
the signal fed into S2 is the turn command (0v turn right, 2.5v go straight, 5v turn left) These are
mixed inside the controller to command right and left wheels. The right wheel should have
switch 6 in the UP position and the left wheel should have switch 6 in the DOWN position. This
mode is useful for controlling vehicles and robots with a joystick or playstation-style controller,
or a throttle pedal and steering wheel.
Switch 6: Analog motor reverse
Switch 6 reverses the direction of the motor driver in all
analog operating modes except Diff-Drive Mix, in which
case it is the right/left select switch. This is sometimes
better than physically reversing the motor connections, but
accomplishes the same thing.
Note on using
filtered PWM
in Analog
Mode
If you are using a
filtered PWM signal from a microcontroller to generate the analog voltage, an R-C filter with
component values 10k ohms and at least .1uf is recommended as shown in Figure 4.1. This will
provide a fast response to changes in duty cycle, and is suitable for PWM rates of 20+kHz.
Using a larger value filter capacitor such as 47uf (Figure 4.2) will result in smoother motor
operation and greater efficiency. However, the transient response will be slower. This extra
capacitance is strongly recommended when using slower PWM frequencies – as low as 1kHz.
Tweaking the value of the capacitor to suit your individual needs is safe way to optimize your
robot’s performance.
Analog Diff-Drive Right Analog Diff-Drive Left
Analog One-direction reverse
Figure 4.1: Fast filtering Figure 4.2: Very smooth filtering