st3m: expose battery charge status

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();

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/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

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