Step counter

docs/tildagon-apps/reference/badge-hardware.md

@@ -372,7 +372,7 @@ To use the `Pin`s:
 
 ## `IMU`
 
-The IMU device is a highly integrated, low power inertial measurement unit (IMU) that combines precise acceleration and angular rate (gyroscopic) measurement. The triple axis device has been configured to measure 2g and 2 degree per second ranges.
+The IMU device is a highly integrated, low power inertial measurement unit (IMU) that combines precise acceleration and angular rate (gyroscopic) measurement. The triple axis device has been configured to measure 2g and 2 degree per second ranges. It also has a step count function intended for wrist mounted applications.
 
 !!! note "More information about the sensor"
 
@@ -409,6 +409,42 @@ class ExampleApp(app.App):
         ctx.restore()
 
 
+__app_export__ = ExampleApp
+```
+
+The following example app measures steps as you walk aroudn with your badge:
+
+```python
+import app
+import imu
+
+from events.input import Buttons, BUTTON_TYPES
+
+
+class ExampleApp(app.App):
+    def __init__(self):
+        self.button_states = Buttons(self)
+        self.acc_read = None
+        self.steps_read = None
+
+    def update(self, delta):
+        if self.button_states.get(BUTTON_TYPES["CANCEL"]):
+            self.button_states.clear()
+            self.minimise()
+        else:
+            self.steps_read = imu.step_counter_read()
+
+    def draw(self, ctx):
+        ctx.save()
+        ctx.rgb(0.2, 0, 0).rectangle(-120, -120, 240, 240).fill()
+        if self.steps_read:
+            ctx.rgb(1, 0, 0).move_to(-80, -40).text(
+                "steps:\n{}\n".format(self.steps_read))
+        else:
+            ctx.rgb(1, 0,  0).move_to(-80, 0).text("no readings yet")
+        ctx.restore()
+
+
 __app_export__ = ExampleApp
 ```
 
@@ -421,6 +457,7 @@ The api currently only allows access to the raw data.
 | ------ | ----------- | --------- | ------- |
 | `acc_read()` | Get the accelerometer data. | None | `(x,y,z)`: The accelerometer data as a tuple of floats (m/s^2). |
 | `gyro_read()` | Get the gyro data. | None | `(x,y,z)`: The gyro data as a tuple of floats (d/s). |
+| `step_counter_read()` | Get the step count | None | `count`: The step count |
 
 ### Usage