draw battery status on display

include/image.h

 void image_draw(char *data, uint width, uint height);
 
 void draw_splash(void);
+void draw_battery_indicator(void);
+void battery_run(void);
 
 #endif // __IMAGE_H__

src/console.c

         println(" splash - draw image on screen");
         println("  fonts - show font list");
         println("   text - draw text on screen");
+        println("    bat - draw battery indicator");
         println("Press Enter with no input to repeat last command.");
         println("Use repeat to continuously execute last command.");
         println("Stop this by calling repeat again.");
             y_off = text.y;
             f = f->next;
         }
+    } else if (strcmp(line, "bat") == 0) {
+        draw_battery_indicator();
     } else {
         println("unknown command \"%s\"", line);
     }

src/image.c

  * See <http://www.gnu.org/licenses/>.
  */
 
+#include <stdio.h>
+
 #include "config.h"
 #include "lcd.h"
 #include "text.h"
+#include "lipo.h"
 #include "image.h"
 
 #pragma GCC diagnostic push
 #include "logo.h"
 #pragma GCC diagnostic pop
 
+#define BATT_INTERVAL_MS 777
+
 void image_draw(char *data, uint width, uint height) {
     for (uint x = 0; x < width; x++) {
         for (uint y = 0; y < height; y++) {
     text_draw(&text1);
 
     struct text_conf text2 = {
-        .text = __DATE__ " " __TIME__,
+        .text = __DATE__ " @ " __TIME__,
         .x = 0,
         .y = 195,
         .justify = false,
     };
     text_draw(&text2);
 }
+
+void draw_battery_indicator(void) {
+    float v = lipo_voltage();
+    static char s[30];
+    if (lipo_charging()) {
+        //                     "Batt:   99.9%   (4.20V)"
+        snprintf(s, sizeof(s), "Batt: Charging! (%.2fV)", v);
+    } else {
+        snprintf(s, sizeof(s), "Batt:   %02.1f%%   (%.2fV)", lipo_percentage(v), v);
+    }
+
+    static struct text_font font = {
+        .fontname = "fixed_10x20",
+        .font = NULL,
+    };
+    if (font.font == NULL) {
+        text_prepare_font(&font);
+    }
+
+    struct text_conf text = {
+        .text = s,
+        .x = 0,
+        .y = 219,
+        .justify = false,
+        .alignment = MF_ALIGN_CENTER,
+        .width = 240,
+        .height = 240,
+        .margin = 2,
+        .bg = RGB_565(0x00, 0x00, 0x00),
+        .font = &font,
+    };
+    text_draw(&text);
+}
+
+void battery_run(void) {
+    static uint32_t last_run = 0;
+    uint32_t now = to_ms_since_boot(get_absolute_time());
+    if (now >= (last_run + BATT_INTERVAL_MS)) {
+        last_run = now;
+        draw_battery_indicator();
+    }
+}

src/lipo.c

  * See <http://www.gnu.org/licenses/>.
  */
 
+#include <math.h>
+
 #include "stdbool.h"
 #include "hardware/adc.h"
 
 
 static const float full_battery = 4.1f;
 static const float empty_battery = 3.2f;
+static const float low_pass_factor = 0.9f;
 
 bool lipo_charging(void) {
 #if defined CYW43_WL_GPIO_VBUS_PIN
 #if CYW43_USES_VSYS_PIN
     cyw43_thread_enter();
     // Make sure cyw43 is awake
-    cyw43_arch_gpio_get(CYW43_WL_GPIO_VBUS_PIN);
+    bool charging = cyw43_arch_gpio_get(CYW43_WL_GPIO_VBUS_PIN);
 #endif
 
     // setup adc
 
     // Generate voltage
     const float conversion_factor = 3.3f / (1 << 12);
-    return vsys * 3 * conversion_factor;
+    float v_now = vsys * 3 * conversion_factor;
+
+    static float v_prev = NAN;
+    if (charging) {
+        v_prev = NAN;
+        return v_now;
+    } else {
+        if (isnan(v_prev)) {
+            v_prev = v_now;
+        }
+        v_prev = (v_prev * low_pass_factor) + (v_now * (1.0f - low_pass_factor));
+        return v_prev;
+    }
 }
 
 float lipo_percentage(float voltage) {
     float percentage = 100.0f * ((voltage - empty_battery) / (full_battery - empty_battery));
-    if (percentage >= 100.0f) {
-        percentage = 100.0f;
+    if (percentage >= 99.9f) {
+        percentage = 99.9f;
     } else if (percentage < 0.0f) {
         percentage = 0.0f;
     }

src/main.c

         buttons_run();
         usb_run();
         cnsl_run();
+
+        battery_run();
     }
 
     return 0;

src/text.c

         return;
     }
 
-    debug("'%s' %d", tc->text, tc->y);
-
     state_t state;
     state.options = tc;