Data Sheet

The signal should be low (0 V) normally and have periodic pulses with an amplitude (V) of at least
2 V. The width of the pulses (t) should be between 200 µs and 2700 µs. The period of the signal (T),
should be at most 100 ms, and the there is no particular lower limit. When the Tic has received three
good pulses in a row, it writes the width of the latest pulse to the “RC pulse width” variable in units of
1/12 µs.
If the Tic goes more than 100 ms without receiving a good pulse, it will change the “RC pulse width”
variable to 0xFFFF (65,535) to indicate that the RC signal has been lost. Furthermore, if the Tic goes
more than 500 ms without receiving three good pulses in a row, it will change the “RC pulse width”
variable to 0xFFFF to indicate the RC signal is unreliable.
Input averaging
The Tic’s input averaging feature, which is enabled by default, helps smooth out noisy RC or analog
input signals by taking a running average.
By default, when the Tic’s control mode is set to any of the RC or analog options, the Tic calculates
a running average of the last four readings (from the “Analog reading SDA” or “RC pulse width”
variables) and stores that average (possibly scaled by a power of two) in the “Input after averaging”
variable. If you disable input averaging by unchecking the “Enable input averaging” checkbox in the
Tic Control Center, then the “Input after averaging” variable is set directly from the corresponding input
variable without averaging.
Input hysteresis
Another optional feature that helps deal with noisy inputs is input hysteresis. The input hysteresis
feature can be useful if you are using a noisy input to set the position of a stepper motor, and you want
the stepper motor to be at rest whenever you are not changing the input, instead of moving around by
small amounts and making noise.
Tic Stepper Motor Controller User’s Guide © 2001–2018 Pololu Corporation
5. Details Page 60 of 150