add widget_battery() which shows the LiPo state of charge

include/mongoose-touch.h

@@ -17,6 +17,8 @@ void widget_topbar_ev(int ev, struct widget_t *w, void *ev_data);
 
 void widget_name_ev(int ev, struct widget_t *w, void *ev_data);
 
+void widget_battery_ev(int ev, struct widget_t *w, void *ev_data);
+
 void widget_default_ev(int ev, struct widget_t *w, void *ev_data);
 
 

mos.yml

@@ -23,6 +23,7 @@ filesystem:
   - fs
 
 config_schema:
+  - ["sys.esp32_adc_vref", 3300] # ADC Vref is 3.3V
   - ["wifi.ap.enable", false]
   - ["wifi.sta.enable", true]
   - ["wifi.sta.ssid", "dapches-iot"]
@@ -48,6 +49,7 @@ libs:
   - origin: https://github.com/mongoose-os-libs/rpc-uart
   - origin: https://github.com/mongoose-os-libs/prometheus-metrics
   - origin: https://github.com/mongoose-os-libs/pwm
+  - origin: https://github.com/mongoose-os-libs/adc
   - origin: libs/lobo-spi
   - origin: libs/ili9341
   - origin: libs/stmpe610

src/main.c

@@ -70,19 +70,24 @@ void tft_demo(void)
     return;
   }
 
-  w = widget_create("name", 0, 0, 198, 20);
+  w = widget_create("name", 0, 0, 185, 20);
   widget_set_handler(w, widget_name_ev, NULL);
   screen_widget_add(screen, w);
 
-  w = widget_create("network", 198, 0, 22, 20);
+  w = widget_create("network", 185, 0, 22, 20);
   widget_set_handler(w, widget_network_ev, NULL);
   screen_widget_add(screen, w);
 
-  w = widget_create("wifi", 220, 0, 20, 20);
+  w = widget_create("wifi", 207, 0, 20, 20);
   widget_set_handler(w, widget_wifi_ev, NULL);
   widget_set_timer(w, 5000);
   screen_widget_add(screen, w);
 
+  w = widget_create("battery", 227, 0, 13, 20);
+  widget_set_handler(w, widget_battery_ev, NULL);
+  widget_set_timer(w, 10000);
+  screen_widget_add(screen, w);
+
   w = widget_create("time", 240, 0, 80, 20);
   widget_set_handler(w, widget_time_ev, NULL);
   widget_set_timer(w, 1000);

src/widget_battery.c

@@ -0,0 +1,62 @@
+#include "mgos.h"
+#include "mgos_adc.h"
+#include "tft.h"
+#include "mongoose-touch.h"
+
+
+#define WIDGET_BATTERY_ADC_PIN 35
+
+// Returns millivolts - Huzzah32 has a 1:1 voltage divider on I35 (A13)
+// so it returns half of the battery voltage. LiPo's are full at 4200mV
+// and critically empty at 3000mV.
+static int widget_battery_getvoltage() {
+  // Value is between 0..4096 which maps to 0..6600mV
+  return (6600*mgos_adc_read(WIDGET_BATTERY_ADC_PIN))/4096;
+}
+
+static void widget_battery_render(struct widget_t *w, void *ev_data) {
+  int mvolts;
+  color_t color;
+  uint8_t h;
+
+  if (!w)
+    return;
+
+  mgos_ili9341_setclipwin(w->x, w->y, w->x+w->w, w->y+w->h);
+
+  mvolts=widget_battery_getvoltage();
+  color=ILI9341_RED;
+  if (mvolts<3200) mvolts=3200;
+  if (mvolts>3500) color=ILI9341_YELLOW;
+  if (mvolts>3900) color=ILI9341_GREEN;
+  if (mvolts>4200) mvolts=4200;
+  h=12-12*(mvolts-3200)/(4200-3200);
+
+  mgos_ili9341_fillRect(5, 2, 3, 2, color);
+  mgos_ili9341_fillRect(2, 4, 9, 14, color);
+  mgos_ili9341_fillRect(3, 5, 7, h, ILI9341_BLACK);
+  mgos_ili9341_resetclipwin();
+
+  (void) ev_data;
+}
+
+void widget_battery_ev(int ev, struct widget_t *w, void *ev_data) {
+  if (!w)
+    return;
+
+  switch(ev) {
+    case EV_WIDGET_CREATE:
+      LOG(LL_INFO, ("Monitoring LiPo voltage on gpio=%d", WIDGET_BATTERY_ADC_PIN));
+      mgos_adc_enable(WIDGET_BATTERY_ADC_PIN);
+    case EV_WIDGET_DRAW:
+    case EV_WIDGET_REDRAW:
+    case EV_WIDGET_TIMER:
+      widget_battery_render(w, ev_data);
+      break;
+    case EV_WIDGET_TOUCH_UP:
+    case EV_WIDGET_TOUCH_DOWN:
+    case EV_WIDGET_DESTROY:
+    default: // EV_WIDGET_NONE
+      break;
+  }
+}