# @name    Bitcoin
# @desc    Bitcoin price via CoinGecko (no API key needed)
# @author  RobG
# @version 1.0
# @config  currency select "Currency"               default=usd options=usd,eur
# @config  every    number "Refresh"                default=5 min=1 max=60 unit=min
# @config  color    color  "Text color"             default=#FFFFFF
# @config  ic       text   "Icon"                   default="12460" help="Icon name/ID from the device icon folder. Missing = orange B"
# @config  compact  bool   "Short format (114.1K)"  default=false

class Bitcoin
  var url, needle, period       # built from the settings in init()
  var color, ic, compact
  var price                     # last known price, nil until the first success
  var label                     # the finished string draw() paints
  var ticks, in_flight          # countdown of loop() calls; request outstanding
  var age                       # seconds since the last successful fetch

  def fmt(v)
    if self.compact && v >= 10000
      return str(round(v / 1000.0, 1)) + "K"
    end
    return str(round(v))
  end

  def init()
    var cur = str(store.get("currency"))
    self.url = "https://api.coingecko.com/api/v3/simple/price?ids=bitcoin&vs_currencies=" + cur
    self.needle = "\"" + cur + "\":"
    self.period = num(store.get("every"), 5) * 60
    self.color = store.get("color")
    self.ic = store.get("ic")
    self.compact = store.get("compact") == true
    self.price = store.get("price")             # survives a reboot: shows instantly
    self.label = self.price == nil ? nil : self.fmt(self.price)
    self.ticks = 0
    self.in_flight = false
    self.age = 0
  end

  def on_body(body, status)
    self.in_flight = false
    if body == nil return end                   # one check, every failure
    var m = re.search("([0-9][0-9.]*)", body)   # body starts at "usd": thanks to find
    if m == nil return end
    var v = num(m[1])
    if v == nil return end
    self.price = v
    self.label = self.fmt(v)
    self.age = 0
    store.set("price", v)                       # only once it is good
  end

  def loop()
    if self.ticks <= 0
      self.ticks = self.period
      if !self.in_flight
        self.in_flight = true
        http.get(self.url, / b, st -> self.on_body(b, st),
                 {'find': self.needle, 'keep': 32})
      end
    end
    self.ticks -= 1
    self.age += 1
  end

  def should_show()
    # nothing fetched yet, or the data has gone stale: skip our turn
    return self.label != nil && self.age < self.period * 3
  end

  def draw()
    clear()
    if !icon(self.ic, 0, 0)
      text(2, 6, "B", 0xF7931A)                 # fallback when the icon is missing
    end
    if self.label != nil
      scroll_text(9, 6, width() - 9, self.label, self.color)
    end
  end
end

return Bitcoin()

These icons belong on the device, in /ICONS. Each one is at most 32×8 pixels — shown here magnified, at their real proportions.