Group 1-04 / Mbed 2 deprecated ME30001_Lab01_Exercise_03b

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Dependencies:   Servo mbed

main.cpp@0:6eab244a5208, 2017-09-22 (annotated)

Committer:
sthompson
Date:
Fri Sep 22 15:10:54 2017 +0000
Revision:
0:6eab244a5208
3bb

Who changed what in which revision?

UserRevisionLine numberNew contents of line
sthompson 0:6eab244a5208 1 /***********************************************************************************
sthompson 0:6eab244a5208 2 / Test program to demonstrate the Parallax standard and continuous rotation servos
sthompson 0:6eab244a5208 3 /
sthompson 0:6eab244a5208 4 / The program oscillates the standard servo position and oscillates the speed and
sthompson 0:6eab244a5208 5 / direction of the continuous rotation servo
sthompson 0:6eab244a5208 6 /
sthompson 0:6eab244a5208 7 / Due to the smaller scale of proportional speed values for the continuous rotation
sthompson 0:6eab244a5208 8 / servo, its resulting command magnitude is reduced by CR_SCALE
sthompson 0:6eab244a5208 9 /
sthompson 0:6eab244a5208 10 / Due to a slight directional bias, the contuous rotation servo command is centred
sthompson 0:6eab244a5208 11 / about 0.515, rather than the standard 0.5 value
sthompson 0:6eab244a5208 12 / (on a scale of 0.0-1.0, 0.5 represents 'centred' for standard servos and 'stop'
sthompson 0:6eab244a5208 13 / for continuous rotation servos)
sthompson 0:6eab244a5208 14 /***********************************************************************************/
sthompson 0:6eab244a5208 15 #include "mbed.h"
sthompson 0:6eab244a5208 16 #include "Servo.h"
sthompson 0:6eab244a5208 17
sthompson 0:6eab244a5208 18 Serial pc(USBTX, USBRX); // USB serial interface
sthompson 0:6eab244a5208 19 Servo cr_srv(p21); // continuous rotation hobby servo
sthompson 0:6eab244a5208 20 Servo std_srv(p22); // standard hobby servo
sthompson 0:6eab244a5208 21 AnalogIn A_in(p20); // analogue input pin for reference values
sthompson 0:6eab244a5208 22
sthompson 0:6eab244a5208 23 #define CR_SCALE 12.0
sthompson 0:6eab244a5208 24
sthompson 0:6eab244a5208 25 void init_servo() {
sthompson 0:6eab244a5208 26 // calibrate the servos for +/-5ms over +/-45deg
sthompson 0:6eab244a5208 27 cr_srv.calibrate(0.0005,45);
sthompson 0:6eab244a5208 28 std_srv.calibrate(0.0005,45);
sthompson 0:6eab244a5208 29 }
sthompson 0:6eab244a5208 30
sthompson 0:6eab244a5208 31 int main() {
sthompson 0:6eab244a5208 32
sthompson 0:6eab244a5208 33 float Ain_readings=0.0;
sthompson 0:6eab244a5208 34 float pos_val=0.5; // variable to hold position values
sthompson 0:6eab244a5208 35 float step_size=0.01; // position increment/decrement value
sthompson 0:6eab244a5208 36 float cr_srv_cmd=0.5; // continuous rotation servo command value (range: 0.0 - 1.0)
sthompson 0:6eab244a5208 37 float std_srv_cmd=0.5; // standard servo command value (range: 0.0 - 1.0)
sthompson 0:6eab244a5208 38
sthompson 0:6eab244a5208 39 // set the USB serial interface baud rate
sthompson 0:6eab244a5208 40 pc.baud(921600);
sthompson 0:6eab244a5208 41
sthompson 0:6eab244a5208 42 init_servo();
sthompson 0:6eab244a5208 43
sthompson 0:6eab244a5208 44 while(1) {
sthompson 0:6eab244a5208 45 // use a sin function to create an oscillating servo postion with values
sthompson 0:6eab244a5208 46 // between 0.0 and 1.0 for the standard servo
sthompson 0:6eab244a5208 47 std_srv_cmd = sin(pos_val*2*3.14159)/2.0+0.5;
sthompson 0:6eab244a5208 48 // use a smaller scale for the continuous rotation servo, due to its limited sensitivity
sthompson 0:6eab244a5208 49 cr_srv_cmd = sin(pos_val*2*3.14159)/CR_SCALE+0.515;
sthompson 0:6eab244a5208 50
sthompson 0:6eab244a5208 51 // sernd the servo command to the servos themselves
sthompson 0:6eab244a5208 52 cr_srv.write(cr_srv_cmd); // write to the continuous rotation servo
sthompson 0:6eab244a5208 53 std_srv.write(std_srv_cmd); // write to the standard servo
sthompson 0:6eab244a5208 54
sthompson 0:6eab244a5208 55 // export the readings to a terminal program via the USB cable
sthompson 0:6eab244a5208 56 pc.printf("pos value: %6.4f, cr servo: %6.4f std servo: %6.4f\r", pos_val, cr_srv_cmd,
sthompson 0:6eab244a5208 57 std_srv_cmd);
sthompson 0:6eab244a5208 58
sthompson 0:6eab244a5208 59 pos_val = Ain_readings + A_in.read(); // increment/decrement the position
sthompson 0:6eab244a5208 60 if (pos_val > 1.0) pos_val = 0.0; // if the position is out of bounds, reset the pos value
sthompson 0:6eab244a5208 61
sthompson 0:6eab244a5208 62 wait(0.250); // wait for 0.25s to give time for the display to show
sthompson 0:6eab244a5208 63 }
sthompson 0:6eab244a5208 64 }