Added battery level example

micropython/examples/badger2040/battery.py

@@ -0,0 +1,115 @@
+import badger2040
+from machine import Pin, ADC
+import time
+
+# Global Constants
+MAX_BATTERY_VOLTAGE = 4.0
+MIN_BATTERY_VOLTAGE = 3.2
+
+WIDTH = badger2040.WIDTH
+HEIGHT = badger2040.HEIGHT
+
+BATT_WIDTH = 200
+BATT_HEIGHT = 100
+BATT_BORDER = 10
+BATT_TERM_WIDTH = 20
+BATT_TERM_HEIGHT = 50
+BATT_BAR_PADDING = 10
+BATT_BAR_HEIGHT = BATT_HEIGHT - (BATT_BORDER * 2) - (BATT_BAR_PADDING * 2)
+BATT_BAR_START = ((WIDTH - BATT_WIDTH) // 2) + BATT_BORDER + BATT_BAR_PADDING
+BATT_BAR_END = ((WIDTH + BATT_WIDTH) // 2) - BATT_BORDER - BATT_BAR_PADDING
+
+NUM_BATT_BARS = 4
+
+
+# ------------------------------
+#      Utility functions
+# ------------------------------
+
+def map_value(input, in_min, in_max, out_min, out_max):
+    return (((input - in_min) * (out_max - out_min)) / (in_max - in_min)) + out_min
+
+
+# ------------------------------
+#      Drawing functions
+# ------------------------------
+
+# Draw the frame of the reader
+def draw_battery(level, resolution):
+    display.pen(15)
+    display.clear()
+
+    display.thickness(1)
+
+    # Draw the battery outline
+    display.pen(0)
+    display.rectangle((WIDTH - BATT_WIDTH) // 2, (HEIGHT - BATT_HEIGHT) // 2,
+                      BATT_WIDTH, BATT_HEIGHT)
+
+    display.rectangle((WIDTH + BATT_WIDTH) // 2, (HEIGHT - BATT_TERM_HEIGHT) // 2,
+                      BATT_TERM_WIDTH, BATT_TERM_HEIGHT)
+
+    display.pen(15)
+    display.rectangle((WIDTH - BATT_WIDTH) // 2 + BATT_BORDER, (HEIGHT - BATT_HEIGHT) // 2 + BATT_BORDER,
+                      BATT_WIDTH - BATT_BORDER * 2, BATT_HEIGHT - BATT_BORDER * 2)
+
+    # Draw the battery bars
+    display.pen(0)
+    length = (BATT_BAR_END - BATT_BAR_START - ((NUM_BATT_BARS - 1) * BATT_BAR_PADDING)) // NUM_BATT_BARS
+    current_level = 0.0
+    normalised_level = level / resolution
+    for i in range(NUM_BATT_BARS):
+        current_level = (1.0 * i) / NUM_BATT_BARS
+        if normalised_level > current_level:
+            pos = i * (length + BATT_BAR_PADDING)
+            display.rectangle(BATT_BAR_START + pos, (HEIGHT - BATT_BAR_HEIGHT) // 2,
+                              length, BATT_BAR_HEIGHT)
+
+    display.update()
+
+
+# ------------------------------
+#        Program setup
+# ------------------------------
+
+# Create a new Badger and set it to update FAST
+display = badger2040.Badger2040()
+display.update_speed(badger2040.UPDATE_FAST)
+
+# Set up the ADCs for measuring battery voltage
+vbat_adc = ADC(badger2040.PIN_BATTERY)
+vref_adc = ADC(badger2040.PIN_1V2_REF)
+vref_en = Pin(badger2040.PIN_VREF_POWER)
+vref_en.init(Pin.OUT)
+vref_en.value(0)
+
+
+# ------------------------------
+#       Main program loop
+# ------------------------------
+
+last_level = -1
+
+while True:
+    # Enable the onboard voltage reference
+    vref_en.value(1)
+
+    # Calculate the logic supply voltage, as will be lower that the usual 3.3V when running off low batteries
+    vdd = 1.24 * (65535 / vref_adc.read_u16())
+    vbat = (vbat_adc.read_u16() / 65535) * 3 * vdd  # 3 in this is a gain, not rounding of 3.3V
+
+    # Disable the onboard voltage reference
+    vref_en.value(0)
+
+    # Print out the voltage
+    print("Battery Voltage = ", vbat, "V", sep="")
+
+    # Convert the voltage to a level to display onscreen
+    level = int(map_value(vbat, MIN_BATTERY_VOLTAGE, MAX_BATTERY_VOLTAGE, 0, NUM_BATT_BARS))
+
+    # Only draw if the battery level has changed significantly
+    if level != last_level:
+        draw_battery(level, NUM_BATT_BARS)
+        last_level = level
+
+    time.sleep(1)

micropython/modules/badger2040/badger2040.c

@@ -106,6 +106,8 @@ STATIC const mp_map_elem_t badger2040_globals_table[] = {
 
     { MP_ROM_QSTR(MP_QSTR_PIN_VBUS_DETECT), MP_ROM_INT(24) },
     { MP_ROM_QSTR(MP_QSTR_PIN_LED), MP_ROM_INT(25) },
+    { MP_ROM_QSTR(MP_QSTR_PIN_VREF_POWER), MP_ROM_INT(27) },
+    { MP_ROM_QSTR(MP_QSTR_PIN_1V2_REF), MP_ROM_INT(28) },
     { MP_ROM_QSTR(MP_QSTR_PIN_BATTERY), MP_ROM_INT(29) },
     { MP_ROM_QSTR(MP_QSTR_PIN_ENABLE_3V3), MP_ROM_INT(10) },
 };