CHANGELOG.md

@@ -6,8 +6,22 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 
-## [1.1.1] - 2023-08-17
 
+## [1.2.0] - 2023-08-18
+### Added
+- Added a WiFi status indicator icon.
+- Added a battery status indicator icon.
+- Added support for loading apps from `/sd/apps` and `/flash/apps`.
+- Added an error screen when apps fail to start.
+- Added Python/st3m API to access battery charge status.
+- Added the ability to always hide icons (*System* ➜ *Settings* ➜ *Show Icons*).
+
+### Fixed
+- File descriptor leak on app load.  This would lead to the OS crashing when
+  too many apps are installed.
+
+
+## [1.1.1] - 2023-08-17
 ### Fixed
 - Crash on WiFi startup
 
@@ -47,7 +61,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 Initial Release
 
 
-[unreleased]: https://git.flow3r.garden/flow3r/flow3r-firmware/-/compare/v1.1.0...main
+[unreleased]: https://git.flow3r.garden/flow3r/flow3r-firmware/-/compare/v1.2.0...main
+[1.2.0]: https://git.flow3r.garden/flow3r/flow3r-firmware/-/compare/v1.1.1...v1.2.0
 [1.1.1]: https://git.flow3r.garden/flow3r/flow3r-firmware/-/compare/v1.1.0...v1.1.1
 [1.1.0]: https://git.flow3r.garden/flow3r/flow3r-firmware/-/compare/v1.0.0...v1.1.0
 [1.0.0]: https://git.flow3r.garden/flow3r/flow3r-firmware/-/tags/v1.0.0

components/micropython/usermodule/mp_sys_kernel.c

@@ -8,6 +8,7 @@
 #include "py/obj.h"
 #include "py/runtime.h"
 #include "st3m_console.h"
+#include "st3m_io.h"
 #include "st3m_usb.h"
 #include "st3m_version.h"
 
@@ -372,6 +373,13 @@ STATIC mp_obj_t mp_i2c_scan(void) {
 
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(mp_i2c_scan_obj, mp_i2c_scan);
 
+STATIC mp_obj_t mp_battery_charging(void) {
+    bool res = st3m_io_charger_state_get();
+    return mp_obj_new_bool(!res);
+}
+
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(mp_battery_charging_obj, mp_battery_charging);
+
 STATIC const mp_rom_map_elem_t globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_scheduler_snapshot),
       MP_ROM_PTR(&mp_scheduler_snapshot_obj) },
@@ -385,6 +393,8 @@ STATIC const mp_rom_map_elem_t globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_usb_console_active),
       MP_ROM_PTR(&mp_usb_console_active_obj) },
     { MP_ROM_QSTR(MP_QSTR_i2c_scan), MP_ROM_PTR(&mp_i2c_scan_obj) },
+    { MP_ROM_QSTR(MP_QSTR_battery_charging),
+      MP_ROM_PTR(&mp_battery_charging_obj) },
 
     { MP_ROM_QSTR(MP_QSTR_RUNNING), MP_ROM_INT(eRunning) },
     { MP_ROM_QSTR(MP_QSTR_READY), MP_ROM_INT(eReady) },

components/st3m/st3m_io.h

@@ -58,3 +58,7 @@ uint8_t st3m_io_badge_link_disable(uint8_t pin_mask);
  * a while. Warn user.
  */
 uint8_t st3m_io_badge_link_enable(uint8_t pin_mask);
+
+/* Returns true if the battery is currently being charged.
+ */
+bool st3m_io_charger_state_get();

docs/api/captouch.rst

 ``captouch`` module
 ===================
 
+.. note::
+
+   Because of a driver quirk, the top pad of the petal 5 is currently not working,
+   resulting in that petal only reporting half of its supposed range.
+
 .. automodule:: captouch
    :members:
    :undoc-members:

docs/badge/programming.rst

@@ -597,9 +597,22 @@ Together with the Python code this file forms a so called bundle
 
 
 Save this as `flow3r.toml` together with the Python code as `__init__.py` in a
-folder (name doesn't matter) and put that folder into the ``/flash/sys/apps``
-folder on your flow3r (visible as ``sys/apps`` in `Disk Mode`_). Restart the
-flow3r and it should pick up your new application.
+folder (name doesn't matter) and put that folder into one of the possible
+application directories (see below) using `Disk Mode`_. Restart the flow3r and
+it should pick up your new application.
+
++--------+----------------------+---------------------+---------------------------------------+
+| Medium | Path in Disk Mode    | Path on Badge       | Notes                                 |
++========+======================+=====================+=======================================+
+| Flash  | ``sys/apps``         | ``/flash/sys/apps`` | “Default” apps.                       |
++--------+----------------------+---------------------+---------------------------------------+
+| Flash  | ``apps``             | ``/flash/apps``     | Doesn't exist by default. Split       |
+|        |                      |                     | from ``sys`` to allow for cleaner     |
+|        |                      |                     | updates.                              |
++--------+----------------------+---------------------+---------------------------------------+
+| SD     | ``apps``             | ``/sd/apps``        | Doesn't exist by default. Will be     |
+|        |                      |                     | retained even across badge reflashes. |
++--------+----------------------+---------------------+---------------------------------------+
 
 Distributing applications
 -------------------------

python_payload/apps/nick/__init__.py

 from st3m.application import Application, ApplicationContext
-from st3m.ui.colours import PUSH_RED, GO_GREEN, BLACK
-from st3m.goose import Dict, Any, Tuple
+from st3m.goose import Tuple, Any
 from st3m.input import InputState
 from ctx import Context
 import leds
 import json
 import math
 
+CONFIG_SCHEMA: dict[str, dict[str, Any]] = {
+    "name": {"types": [str]},
+    "size": {"types": [int, float], "cast_to": int},
+    "font": {"types": [int, float], "cast_to": int},
+    "pronouns": {"types": ["list_of_str"]},
+    "pronouns_size": {"types": [int, float], "cast_to": int},
+    "color": {"types": ["hex_color"]},
+    "mode": {"types": [int, float], "cast_to": int},
+}
+
 
 class Configuration:
     def __init__(self) -> None:
@@ -17,6 +26,7 @@ class Configuration:
         self.pronouns_size: int = 25
         self.color = "0x40ff22"
         self.mode = 0
+        self.config_errors: list[str] = []
 
     @classmethod
     def load(cls, path: str) -> "Configuration":
@@ -27,39 +37,52 @@ class Configuration:
             data = json.loads(jsondata)
         except OSError:
             data = {}
-        if "name" in data and type(data["name"]) == str:
-            res.name = data["name"]
-        if "size" in data:
-            if type(data["size"]) == float:
-                res.size = int(data["size"])
-            if type(data["size"]) == int:
-                res.size = data["size"]
-        if "font" in data and type(data["font"]) == int:
-            res.font = data["font"]
-        # type checks don't look inside collections
-        if (
-            "pronouns" in data
-            and type(data["pronouns"]) == list
-            and set([type(x) for x in data["pronouns"]]) == {str}
-        ):
-            res.pronouns = data["pronouns"]
-        if "pronouns_size" in data:
-            if type(data["pronouns_size"]) == float:
-                res.pronouns_size = int(data["pronouns_size"])
-            if type(data["pronouns_size"]) == int:
-                res.pronouns_size = data["pronouns_size"]
-        if (
-            "color" in data
-            and type(data["color"]) == str
-            and data["color"][0:2] == "0x"
-            and len(data["color"]) == 8
-        ):
-            res.color = data["color"]
-        if "mode" in data:
-            if type(data["mode"]) == float:
-                res.mode = int(data["mode"])
-            if type(data["mode"]) == int:
-                res.mode = data["mode"]
+        except ValueError:
+            res.config_errors = ["nick.json decode failed!"]
+            data = {}
+
+        # verify the config format and generate an error message
+        config_type_errors: list[str] = []
+        for config_key, type_data in CONFIG_SCHEMA.items():
+            if config_key not in data.keys():
+                continue
+            key_type_valid = False
+            for allowed_type in type_data["types"]:
+                if isinstance(allowed_type, type):
+                    if isinstance(data[config_key], allowed_type):
+                        key_type_valid = True
+                        break
+                elif allowed_type == "list_of_str":
+                    if isinstance(data[config_key], list) and (
+                        len(data[config_key]) == 0
+                        or set([type(x) for x in data[config_key]]) == {str}
+                    ):
+                        key_type_valid = True
+                        break
+                elif allowed_type == "hex_color":
+                    if (
+                        isinstance(data[config_key], str)
+                        and data[config_key][0:2] == "0x"
+                        and len(data[config_key]) == 8
+                    ):
+                        key_type_valid = True
+                        break
+
+            if not key_type_valid:
+                config_type_errors.append(config_key)
+            else:
+                # Cast to relevant type if needed
+                if type_data.get("cast_to"):
+                    data[config_key] = type_data["cast_to"](data[config_key])
+                setattr(res, config_key, data[config_key])
+
+        if config_type_errors:
+            res.config_errors += [
+                "data types wrong",
+                "in nick.json for:",
+                "",
+            ] + config_type_errors
+
         return res
 
     def save(self, path: str) -> None:
@@ -106,6 +129,19 @@ class NickApp(Application):
         ctx.rgb(0, 0, 0).rectangle(-120, -120, 240, 240).fill()
         ctx.rgb(*self._config.to_normalized_tuple())
 
+        if self._config.config_errors:
+            draw_y = (-20 * len(self._config.config_errors)) / 2
+            ctx.move_to(0, draw_y)
+            ctx.font_size = 20
+            # 0xff4500, red
+            ctx.rgb(1, 0.41, 0)
+            ctx.font = ctx.get_font_name(8)
+            for config_error in self._config.config_errors:
+                draw_y += 20
+                ctx.move_to(0, draw_y)
+                ctx.text(config_error)
+            return
+
         ctx.move_to(0, 0)
         ctx.save()
         if self._config.mode == 0:
@@ -132,7 +168,8 @@ class NickApp(Application):
         # ctx.fill()
 
     def on_exit(self) -> None:
-        self._config.save(self._filename)
+        if not self._config.config_errors:
+            self._config.save(self._filename)
 
     def think(self, ins: InputState, delta_ms: int) -> None:
         super().think(ins, delta_ms)

python_payload/mypystubs/captouch.pyi

@@ -89,12 +89,12 @@ class CaptouchState(Protocol):
         """
         State of individual petals.
 
-        Contains 10 elements, with the zeroth element being the pad closest to
-        the USB port. Then, every other pad in a clockwise direction.
+        Contains 10 elements, with the zeroth element being the petal closest to
+        the USB port. Then, every other petal in a clockwise direction.
 
-        Pads 0, 2, 4, 6, 8 are Top pads.
+        Petals 0, 2, 4, 6, 8 are Top petals.
 
-        Pads 1, 3, 5, 7, 9 are Bottom pads.
+        Petals 1, 3, 5, 7, 9 are Bottom petals.
         """
         ...
 

python_payload/mypystubs/sys_kernel.pyi

@@ -71,3 +71,4 @@ def usb_console_active() -> bool: ...
 def hardware_version() -> str: ...
 def firmware_version() -> str: ...
 def i2c_scan() -> list[int]: ...
+def battery_charging() -> bool: ...

python_payload/st3m/application.py

@@ -6,14 +6,16 @@ from st3m.ui.view import (
 )
 from st3m.ui.menu import MenuItem
 from st3m.input import InputState
-from st3m.goose import Optional, List, Enum
+from st3m.goose import Optional, List, Enum, Dict
 from st3m.logging import Log
+from ctx import Context
 
 import toml
 import os
 import os.path
 import stat
 import sys
+import random
 
 log = Log(__name__)
 
@@ -52,6 +54,7 @@ class BundleLoadException(BaseException):
         res = self.MSG
         if msg is not None:
             res += ": " + msg
+        self.msg = res
         super().__init__(res)
 
 
@@ -97,7 +100,7 @@ class BundleMetadata:
     This data is used to discover bundles and load them as applications.
     """
 
-    __slots__ = ["path", "name", "menu", "_t"]
+    __slots__ = ["path", "name", "menu", "_t", "version"]
 
     def __init__(self, path: str) -> None:
         self.path = path.rstrip("/")
@@ -109,9 +112,12 @@ class BundleMetadata:
         try:
             t = toml.load(f)
         except toml.TomlDecodeError as e:
+            f.close()
             raise BundleMetadataCorrupt(str(e))
         except Exception as e:
+            f.close()
             raise BundleMetadataCorrupt(str(e))
+        f.close()
 
         if "app" not in t or type(t["app"]) != dict:
             raise BundleMetadataBroken("missing app section")
@@ -126,6 +132,11 @@ class BundleMetadata:
         if self.menu not in ["Apps", "Music", "Badge", "Hidden"]:
             raise BundleMetadataBroken("app.menu must be either Apps, Music or Badge")
 
+        version = 0
+        if t.get("metadata") is not None:
+            version = t["metadata"].get("version", 0)
+        self.version = version
+
         self._t = t
 
     @staticmethod
@@ -193,8 +204,74 @@ class BundleMetadata:
             return []
         return [MenuItemAppLaunch(self)]
 
+    @property
+    def source(self) -> str:
+        return os.path.dirname(self.path)
+
+    @property
+    def id(self) -> str:
+        return os.path.basename(self.path)
+
     def __repr__(self) -> str:
-        return f"<BundleMetadata: {self.name} at {self.path}>"
+        return f"<BundleMetadata: {self.id} at {self.path}>"
+
+
+class LoadErrorView(BaseView):
+    def __init__(self, e: BundleLoadException) -> None:
+        super().__init__()
+        self.e = e
+        self.header = "oh no"
+
+    def on_enter(self, vm: Optional[ViewManager]) -> None:
+        self.header = random.choice(
+            [
+                "oh no",
+                "aw shucks",
+                "whoopsie",
+                "ruh-roh",
+                "aw crud",
+            ]
+        )
+
+    def think(self, ins: InputState, delta_ms: int) -> None:
+        pass
+
+    def draw(self, ctx: Context) -> None:
+        ctx.rgb(0.8, 0.1, 0.1)
+        ctx.rectangle(-120, -120, 240, 240)
+        ctx.fill()
+
+        ctx.gray(1)
+        ctx.font_size = 20
+        ctx.font = "Camp Font 1"
+        ctx.text_align = ctx.MIDDLE
+        ctx.move_to(0, -70)
+        ctx.text(self.header)
+
+        lines: List[List[str]] = []
+        msg = self.e.msg
+        for word in msg.split():
+            if len(lines) == 0:
+                lines.append([word])
+                continue
+            lastline = lines[-1][:]
+            lastline.append(word)
+            if sum(len(l) for l in lastline) + len(lastline) - 1 > 30:
+                lines.append([word])
+            else:
+                lines[-1].append(word)
+
+        ctx.gray(0)
+        ctx.rectangle(-120, -60, 240, 240).fill()
+        y = -40
+        ctx.gray(1)
+        ctx.font_size = 15
+        ctx.font = "Arimo Regular"
+        ctx.text_align = ctx.LEFT
+        for line in lines:
+            ctx.move_to(-90, y)
+            ctx.text(" ".join(line))
+            y += 15
 
 
 class MenuItemAppLaunch(MenuItem):
@@ -218,6 +295,8 @@ class MenuItemAppLaunch(MenuItem):
                 self._instance = self._bundle.load()
             except BundleLoadException as e:
                 log.error(f"Could not load {self.label()}: {e}")
+                err = LoadErrorView(e)
+                vm.push(err)
                 return
         assert self._instance is not None
         vm.push(self._instance, ViewTransitionSwipeLeft())
@@ -226,6 +305,80 @@ class MenuItemAppLaunch(MenuItem):
         return self._bundle.name
 
 
+class BundleManager:
+    """
+    The BundleManager maintains information about BundleMetadata at different
+    locations in the badge filesystem.
+
+    It also manages updating/reloading bundles.
+    """
+
+    def __init__(self) -> None:
+        self.bundles: Dict[str, BundleMetadata] = {}
+
+    @staticmethod
+    def _source_trumps(a: str, b: str) -> bool:
+        prios = {
+            "/flash/sys/apps": 200,
+            "/sd/apps": 120,
+            "/flash/apps": 100,
+        }
+        prio_a = prios.get(a, 0)
+        prio_b = prios.get(b, 0)
+        return prio_a > prio_b
+
+    def _discover_at(self, path: str) -> None:
+        path = path.rstrip("/")
+        try:
+            l = os.listdir(path)
+        except Exception as e:
+            log.warning(f"Could not discover bundles in {path}: {e}")
+            l = []
+
+        for d in l:
+            dirpath = path + "/" + d
+            st = os.stat(dirpath)
+            if not stat.S_ISDIR(st[0]):
+                continue
+
+            tomlpath = dirpath + "/flow3r.toml"
+            try:
+                st = os.stat(tomlpath)
+                if not stat.S_ISREG(st[0]):
+                    continue
+            except Exception:
+                continue
+
+            try:
+                b = BundleMetadata(dirpath)
+            except BundleLoadException as e:
+                log.error(f"Failed to bundle from {dirpath}: {e}")
+                continue
+
+            id_ = b.id
+            if id_ not in self.bundles:
+                self.bundles[id_] = b
+                continue
+            ex = self.bundles[id_]
+
+            # Do we have a newer version?
+            if b.version > ex.version:
+                self.bundles[id_] = b
+                continue
+            # Do we have a higher priority source?
+            if self._source_trumps(b.source, ex.source):
+                self.bundles[id_] = b
+                continue
+            log.warning(
+                f"Ignoring {id_} at {b.source} as it already exists at {ex.source}"
+            )
+
+    def update(self) -> None:
+        self._discover_at("/flash/sys/apps")
+        self._discover_at("/flash/apps")
+        self._discover_at("/sd/apps")
+
+
 def discover_bundles(path: str) -> List[BundleMetadata]:
     """
     Discover valid bundles (directories containing flow3r.toml) inside a given

python_payload/st3m/power.py

 import machine
 import time
+import sys_kernel
 
 
 class Power:
@@ -29,3 +30,42 @@ class Power:
     def battery_voltage(self) -> float:
         self._update()
         return self._battery_voltage
+
+    @property
+    def battery_charging(self) -> bool:
+        """
+        True if the battery is currently being charged.
+        """
+        return sys_kernel.battery_charging()
+
+
+def approximate_battery_percentage(voltage: float) -> float:
+    """
+    Returns approximate battery percentage ([0,100]) based on battery voltage
+    (in volts).
+    """
+    if voltage > 4.20:
+        return 100
+    piecewise = [
+        (100, 4.20),
+        (90, 4.06),
+        (80, 3.98),
+        (70, 3.92),
+        (60, 3.87),
+        (50, 3.82),
+        (40, 3.79),
+        (30, 3.77),
+        (20, 3.74),
+        (10, 3.68),
+        (5, 3.45),
+        (0, 3.00),
+    ]
+    for (p1, v1), (p2, v2) in zip(piecewise, piecewise[1:]):
+        if voltage > v1 or voltage < v2:
+            continue
+        vr = v1 - v2
+        pr = p1 - p2
+        vd = voltage - v2
+        p = vd / vr
+        return pr * p + p2
+    return 0

python_payload/st3m/run.py

@@ -11,7 +11,7 @@ from st3m.ui.menu import (
 from st3m.ui.elements import overlays
 from st3m.ui.view import View, ViewManager, ViewTransitionBlend
 from st3m.ui.elements.menus import SimpleMenu, SunMenu
-from st3m.application import discover_bundles, BundleMetadata, MenuItemAppLaunch
+from st3m.application import BundleManager, BundleMetadata, MenuItemAppLaunch
 from st3m.about import About
 from st3m import settings, logging, processors, wifi
 
@@ -52,9 +52,11 @@ def run_responder(r: Responder) -> None:
     reactor.run()
 
 
-def _make_bundle_menu(bundles: List[BundleMetadata], kind: str) -> SimpleMenu:
+def _make_bundle_menu(mgr: BundleManager, kind: str) -> SimpleMenu:
     entries: List[MenuItem] = [MenuItemBack()]
-    for bundle in bundles:
+    ids = sorted(mgr.bundles.keys())
+    for id in ids:
+        bundle = mgr.bundles[id]
         entries += bundle.menu_entries(kind)
     return SimpleMenu(entries)
 
@@ -93,6 +95,15 @@ def _make_compositor(reactor: Reactor, vm: ViewManager) -> overlays.Compositor:
     settings.onoff_debug_touch.subscribe(_onoff_debug_touch_update)
     compositor.add_overlay(debug_touch)
 
+    # Tie compositor's icon visibility to setting.
+    def _onoff_show_tray_update() -> None:
+        compositor.enabled[
+            overlays.OverlayKind.Indicators
+        ] = settings.onoff_show_tray.value
+
+    _onoff_show_tray_update()
+    settings.onoff_show_tray.subscribe(_onoff_show_tray_update)
+
     # Add icon tray.
     compositor.add_overlay(overlays.IconTray())
     return compositor
@@ -127,7 +138,8 @@ def run_main() -> None:
     audio.set_volume_dB(-10)
     leds.set_rgb(0, 255, 0, 0)
     leds.update()
-    bundles = discover_bundles("/flash/sys/apps")
+    bundles = BundleManager()
+    bundles.update()
 
     settings.load_all()
     menu_settings = settings.build_menu()
@@ -152,8 +164,7 @@ def run_main() -> None:
         ],
     )
     if override_main_app is not None:
-        requested = [b for b in bundles if b.name == override_main_app]
-        print([b.name for b in bundles])
+        requested = [b for b in bundles.bundles.values() if b.name == override_main_app]
         if len(requested) > 1:
             raise Exception(f"More than one bundle named {override_main_app}")
         if len(requested) == 0:

python_payload/st3m/settings.py

@@ -297,8 +297,10 @@ onoff_camp_wifi = OnOffTunable("Connect Camp WiFi", "system.camp_wifi_enabled",
 onoff_button_swap = OnOffTunable("Swap Buttons", "system.swap_buttons", False)
 onoff_debug = OnOffTunable("Debug Overlay", "system.debug", False)
 onoff_debug_touch = OnOffTunable("Touch Overlay", "system.debug_touch", False)
+onoff_show_tray = OnOffTunable("Show Icons", "system.show_icons", True)
 all_settings: List[UnaryTunable] = [
     onoff_camp_wifi,
+    onoff_show_tray,
     onoff_button_swap,
     onoff_debug,
     onoff_debug_touch,

python_payload/st3m/ui/elements/overlays.py

@@ -11,6 +11,7 @@ from st3m.goose import Dict, Enum, List, ABCBase, abstractmethod, Optional
 from st3m.utils import tau
 from st3m.ui.view import ViewManager
 from st3m.input import power
+from st3m.power import approximate_battery_percentage
 from ctx import Context
 import st3m.wifi
 
@@ -347,6 +348,8 @@ class Icon(Responder):
     that contains it.
     """
 
+    WIDTH: int = 25
+
     @abstractmethod
     def visible(self) -> bool:
         ...
@@ -359,6 +362,8 @@ class USBIcon(Icon):
     Might or might not be related to a certain serial bus.
     """
 
+    WIDTH: int = 20
+
     def visible(self) -> bool:
         return sys_kernel.usb_connected()
 
@@ -378,6 +383,8 @@ class USBIcon(Icon):
 
 
 class WifiIcon(Icon):
+    WIDTH: int = 15
+
     def __init__(self) -> None:
         super().__init__()
         self._rssi: float = -120
@@ -393,17 +400,61 @@ class WifiIcon(Icon):
         b = w / 2 - 3.14 / 2
 
         r = self._rssi
-        ctx.gray(1.0 if r > -775 else 0.2)
-        ctx.arc(0, 60, 100, a, b, 0).stroke()
+        ctx.gray(1.0 if r > -75 else 0.2)
+        ctx.arc(0, 65, 100, a, b, 0).stroke()
         ctx.gray(1.0 if r > -85 else 0.2)
-        ctx.arc(0, 60, 70, a, b, 0).stroke()
+        ctx.arc(0, 65, 70, a, b, 0).stroke()
         ctx.gray(1.0 if r > -95 else 0.2)
-        ctx.arc(0, 60, 40, a, b, 0).stroke()
+        ctx.arc(0, 65, 40, a, b, 0).stroke()
 
     def think(self, ins: InputState, delta_ms: int) -> None:
         self._rssi = st3m.wifi.rssi()
 
 
+class BatteryIcon(Icon):
+    def __init__(self) -> None:
+        super().__init__()
+        self._percent = 100.0
+        self._charging = False
+
+    def visible(self) -> bool:
+        return True
+
+    def draw(self, ctx: Context) -> None:
+        if self._percent > 30:
+            ctx.rgb(0.17, 0.55, 0.04)
+        else:
+            ctx.rgb(0.52, 0.04, 0.17)
+
+        height = 160 * self._percent / 100
+        ctx.rectangle(-80, -50, height, 100)
+        ctx.fill()
+
+        ctx.gray(0.8)
+        ctx.line_width = 10.0
+        ctx.rectangle(80, -50, -160, 100)
+        ctx.stroke()
+        ctx.rectangle(100, -30, -20, 60)
+        ctx.fill()
+
+        if self._charging:
+            ctx.gray(1)
+            ctx.line_width = 20
+            ctx.move_to(10, -65 - 10)
+            ctx.line_to(-30, 20 - 10)
+            ctx.line_to(30, -20 - 10)
+            ctx.line_to(-10, 65 - 10)
+            ctx.line_to(-20, 35 - 10)
+            ctx.stroke()
+            ctx.move_to(-10, 65 - 10)
+            ctx.line_to(40, 35 - 10)
+            ctx.stroke()
+
+    def think(self, ins: InputState, delta_ms: int) -> None:
+        self._percent = approximate_battery_percentage(power.battery_voltage)
+        self._charging = power.battery_charging
+
+
 class IconTray(Overlay):
     """
     An overlay which renders Icons.
@@ -413,6 +464,7 @@ class IconTray(Overlay):
 
     def __init__(self) -> None:
         self.icons = [
+            BatteryIcon(),
             USBIcon(),
             WifiIcon(),
         ]
@@ -424,14 +476,16 @@ class IconTray(Overlay):
             v.think(ins, delta_ms)
 
     def draw(self, ctx: Context) -> None:
-        nicons = len(self.visible)
-        dist = 25
-        width = (nicons - 1) * dist
-        x0 = width / -2
+        if len(self.visible) < 1:
+            return
+        width = 0
+        for icon in self.visible:
+            width += icon.WIDTH
+        x0 = width / -2 + self.visible[0].WIDTH / 2
         for i, v in enumerate(self.visible):
-            x = x0 + i * dist
             ctx.save()
-            ctx.translate(x, -100)
+            ctx.translate(x0, -100)
             ctx.scale(0.1, 0.1)
             v.draw(ctx)
             ctx.restore()
+            x0 = x0 + v.WIDTH

sim/fakes/sys_kernel.py

@@ -31,3 +31,7 @@ def freertos_sleep(ms):
 
 def i2c_scan():
     return [16, 44, 45, 85, 109, 110]
+
+
+def battery_charging():
+    return True