CPA UI flow with a PiFace

cpa-ui-flow.py

import pifacecad
import string

# Create object
cad = pifacecad.PiFaceCAD()
cad.lcd.backlight_on()

# Config
code_length = 8
characters = list(string.digits + string.ascii_lowercase)

# State
state = "RADIO"
current_character = 0
current_cursor_pos = 0
code = []

# Functions
def cursor_off():
  cad.lcd.cursor_off()
  cad.lcd.blink_off()

def cursor_on():
  cad.lcd.cursor_on()

def write(line_1="", line_2=""):
  cad.lcd.clear()
  cad.lcd.write(line_1)
  cad.lcd.set_cursor(0, 1)
  cad.lcd.write(line_2)

def button_label(label):
  cad.lcd.set_cursor(9, 2)
  cad.lcd.write(label)

def next_character():
  global current_character
  current_character = current_character + 1
  display_current_character()

def previous_character():
  global current_character
  current_character = current_character - 1
  display_current_character()

def cpa_confirm():
  global state
  state = "RADIO"
  cursor_off()
  write("Paired!")

def confirm_character():
  print("confirm")
  global current_cursor_pos
  global current_character
  global code

  # Store confirmed characters
  code.append(get_current_character())

  if len(code) == 8:
    cpa_confirm()
  else:
    # Reset
    current_character = 0
    current_cursor_pos = current_cursor_pos + 1
    display_current_character()

def get_current_character():
  return characters[current_character]

def display_current_character():
  cad.lcd.set_cursor(current_cursor_pos, 2)
  cad.lcd.write(characters[current_character])
  cad.lcd.set_cursor(current_cursor_pos, 2)

def start_input():
  global current_cursor_pos
  global current_character
  current_cursor_pos = 0
  current_character = 0
  cursor_on()
  display_current_character()

def link_ok():
  global state
  state = "CPA"
  cursor_off()
  write("Code:")
  start_input()

def button_event(event):
  pin = event.pin_num

  if pin == 0 and state == "RADIO":
    begin_cpa()
  elif pin == 4 and state == "START_CPA":
    link_ok()
  elif pin == 5 and state == "CPA":
    confirm_character()
  elif pin == 6 and state == "CPA":
    previous_character()
  elif pin == 7 and state == "CPA":
    next_character()
  else:
    now_playing("Radio 1")

  print(state, pin, "".join(code))

def init_listeners():
  listener = pifacecad.SwitchEventListener(chip=cad)
  for i in range(8):
    listener.register(i, pifacecad.IODIR_FALLING_EDGE, button_event)
  listener.activate()

def now_playing(station):
  cursor_off()
  write("Now playing: ", station)

def begin_cpa():
  global state
  state = "START_CPA"
  write("Go to bit.ly/1riff3h")
  button_label("OK")

def init():
  init_listeners()
  now_playing("Radio 1")


init()