Instantly share code, notes, and snippets.

Embed
What would you like to do?
Red Rover Trundle Plot - tape a marker to your Red Rover and it draws a flower-like figure
/*
Red Rover Trundle Plot - tape a marker to your Red Rover
and it draws a flower-like figure
Plot **should** stay within 450 × 600 mm (US Arch C) pad
and likely will fit ISO A2 pads, but **test first**
and don't blame us for any stainage …
Rover motors appear on Arduino as two servos on pins 5 & 6
scruss - 2017-11 - for Elmwood Electronics, elmwood.to
Product page:
https://elmwoodelectronics.ca/products/red-rover-robot-chassis-kit-with-dc-motors-and-motor-controller
Blog post with more information:
https://elmwoodelectronics.ca/blogs/news/red-rover-red-rover-well-send-it-right-over
*/
#include <Servo.h>
Servo lefty, righty;
/*
drive - helper function to map motor speed (-100…100%) to
Servo.write() input range (0…180°)
Input:
< 0 : reverse
0 : stop
> 0 : forward
Output:
constrained to valid Servo.write() input range
Red Rover controller has effective deadband/ stop band
of 87…93°, but requesting very low speeds may not
result in expected motion
Uses integer maths, so expect rounding/truncation.
*/
int drive(int speed) {
if (speed < 0) {
// reverse: -100…0% → 0…87°
// inputs *and* outputs need to be constrained to valid range
// as map() does no range checking
return constrain(map(constrain(speed, -100, 0), -100, 0, 0, 87),
0, 87);
}
if (speed > 0) {
// forward: 0…100% → 93…180°
return constrain(map(constrain(speed, 0, 100), 0, 100, 93, 180),
93, 180);
}
// default: stop
return 90;
}
void setboth(int left, int right) {
// helper to set both left & right motors between -100…+100% speed
lefty.write(drive(left));
righty.write(drive(right));
}
void setup() {
lefty.attach(5, 1000, 2000); // left servo: pin 5
righty.attach(6, 1000, 2000); // right servo: pin 6
setboth(0, 0); // initial state is stopped
}
void loop() {
// veer right forwards by setting left motor a bit faster (75%)
// than the right motor (60%)
setboth(75, 60);
delay(750); // trundle merrily onwards for ¾s
// now stop abruptly
setboth(0, 0);
delay(250); // give it ¼s settling time
// veer left backwards: right now faster than left
setboth(-60, -75);
delay(750); // same backwards trundle time as forwards,
// else Red Rover spirals off into shrubbery
// stop abruptly again and settle
setboth(0, 0);
delay(250);
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment