Biorobotics 7 / Mbed 2 deprecated State_Machine

State machine

Dependencies:   mbed Adafruit_GFX BioroboticsMotorControl MODSERIAL BioroboticsEMGFilter

Button.h@7:e7f808875bc4, 2018-10-31 (annotated)

Committer:
brass_phoenix
Date:
Wed Oct 31 05:58:51 2018 +0000
Revision:
7:e7f808875bc4
Parent:
3:4b19b6cf6cc7
Child:
9:27d00b64076e
* Changed to a button polling scheme. This because our buttons seem to generate more chatter than the rise and fall interrupts of the mbed can handle.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
brass_phoenix 1:cfa5abca6d43 1 #pragma once
brass_phoenix 1:cfa5abca6d43 2
brass_phoenix 1:cfa5abca6d43 3 #include "mbed.h"
brass_phoenix 1:cfa5abca6d43 4
brass_phoenix 3:4b19b6cf6cc7 5 class Button
brass_phoenix 3:4b19b6cf6cc7 6 {
brass_phoenix 1:cfa5abca6d43 7 private:
brass_phoenix 7:e7f808875bc4 8 DigitalIn pin;
brass_phoenix 3:4b19b6cf6cc7 9
brass_phoenix 7:e7f808875bc4 10 volatile bool last_state;
brass_phoenix 1:cfa5abca6d43 11 volatile bool pressed;
brass_phoenix 3:4b19b6cf6cc7 12
brass_phoenix 1:cfa5abca6d43 13 volatile bool just_switched_to_pressed;
brass_phoenix 1:cfa5abca6d43 14 volatile bool just_got_pressed;
brass_phoenix 3:4b19b6cf6cc7 15
brass_phoenix 1:cfa5abca6d43 16 public:
brass_phoenix 1:cfa5abca6d43 17 Button(PinName pin_name):
brass_phoenix 3:4b19b6cf6cc7 18 pin(pin_name) {
brass_phoenix 3:4b19b6cf6cc7 19
brass_phoenix 7:e7f808875bc4 20 last_state = false;
brass_phoenix 1:cfa5abca6d43 21 pressed = false;
brass_phoenix 7:e7f808875bc4 22
brass_phoenix 7:e7f808875bc4 23 just_switched_to_pressed = false;
brass_phoenix 7:e7f808875bc4 24 just_got_pressed = false;
brass_phoenix 7:e7f808875bc4 25 }
brass_phoenix 7:e7f808875bc4 26
brass_phoenix 7:e7f808875bc4 27 void poll_pin() {
brass_phoenix 7:e7f808875bc4 28 // We need to poll the pins periodically.
brass_phoenix 7:e7f808875bc4 29 // Normally one would use rise and fall interrupts, so this wouldn't be
brass_phoenix 7:e7f808875bc4 30 // needed. But the buttons we use generate so much chatter that
brass_phoenix 7:e7f808875bc4 31 // sometimes a rising or a falling edge doesn't get registered.
brass_phoenix 7:e7f808875bc4 32 // With all the confusion that accompanies it.
brass_phoenix 7:e7f808875bc4 33
brass_phoenix 7:e7f808875bc4 34 bool state = !pin;
brass_phoenix 7:e7f808875bc4 35
brass_phoenix 7:e7f808875bc4 36 // Debounce the button by looking over two periods.
brass_phoenix 7:e7f808875bc4 37 if (last_state && state) {
brass_phoenix 7:e7f808875bc4 38 pressed = true;
brass_phoenix 7:e7f808875bc4 39 just_switched_to_pressed = true;
brass_phoenix 7:e7f808875bc4 40 }
brass_phoenix 7:e7f808875bc4 41
brass_phoenix 7:e7f808875bc4 42 if (!state) {
brass_phoenix 7:e7f808875bc4 43 pressed = false;
brass_phoenix 7:e7f808875bc4 44 }
brass_phoenix 7:e7f808875bc4 45
brass_phoenix 7:e7f808875bc4 46 last_state = state;
brass_phoenix 1:cfa5abca6d43 47 }
brass_phoenix 3:4b19b6cf6cc7 48
brass_phoenix 1:cfa5abca6d43 49 void update() {
brass_phoenix 1:cfa5abca6d43 50 if (just_got_pressed) {
brass_phoenix 1:cfa5abca6d43 51 just_got_pressed = false;
brass_phoenix 1:cfa5abca6d43 52 }
brass_phoenix 1:cfa5abca6d43 53 if (just_switched_to_pressed) {
brass_phoenix 1:cfa5abca6d43 54 just_got_pressed = true;
brass_phoenix 1:cfa5abca6d43 55 just_switched_to_pressed = false;
brass_phoenix 1:cfa5abca6d43 56 }
brass_phoenix 1:cfa5abca6d43 57 }
brass_phoenix 3:4b19b6cf6cc7 58
brass_phoenix 3:4b19b6cf6cc7 59 bool is_pressed() {
brass_phoenix 3:4b19b6cf6cc7 60 return pressed;
brass_phoenix 3:4b19b6cf6cc7 61 };
brass_phoenix 1:cfa5abca6d43 62 // Only active just after a state change from not pressed to pressed.
brass_phoenix 1:cfa5abca6d43 63 // Get's reset after `update()` is called.
brass_phoenix 3:4b19b6cf6cc7 64 bool has_just_been_pressed() {
brass_phoenix 3:4b19b6cf6cc7 65 return just_got_pressed;
brass_phoenix 3:4b19b6cf6cc7 66 };
brass_phoenix 1:cfa5abca6d43 67 };