show battery indicator (requires implementing D2 on board)

adc.c

@@ -25,6 +25,7 @@
 #define ADC_TR(low, high)               (((uint32_t)(high) << 16U) |        \
                                          (uint32_t)(low))
 #define ADC_SMPR_SMP_1P5        0U  /**< @brief 14 cycles conversion time   */
+#define ADC_SMPR_SMP_239P5      7U  /**< @brief 252 cycles conversion time. */ 
 #define ADC_CFGR1_RES_12BIT             (0U << 3U)
 
 void adc_init(void)
@@ -61,7 +62,7 @@ uint16_t adc_single_read(ADC_TypeDef *adc, uint32_t chsel)
   adc->ISR    = adc->ISR;
   adc->IER    = 0;
   adc->TR     = ADC_TR(0, 0);
-  adc->SMPR   = ADC_SMPR_SMP_1P5;
+  adc->SMPR   = ADC_SMPR_SMP_239P5;
   adc->CFGR1  = ADC_CFGR1_RES_12BIT;
   adc->CHSELR = chsel;
 
@@ -74,6 +75,32 @@ uint16_t adc_single_read(ADC_TypeDef *adc, uint32_t chsel)
   return adc->DR;
 }
 
+int16_t adc_vbat_read(ADC_TypeDef *adc)
+{
+#define ADC_FULL_SCALE 3300
+#define VBAT_DIODE_VF 500
+#define VREFINT_CAL (*((uint16_t*)0x1FFFF7BA))
+	float vbat = 0;
+	float vrefint = 0;
+
+	ADC->CCR |= ADC_CCR_VREFEN | ADC_CCR_VBATEN;
+	// VREFINT == ADC_IN17
+	vrefint = adc_single_read(adc, ADC_CHSELR_CHSEL17);
+	// VBAT == ADC_IN18
+	// VBATEN enables resiter devider circuit. It consume vbat power.
+	vbat = adc_single_read(adc, ADC_CHSELR_CHSEL18);
+	ADC->CCR &= ~(ADC_CCR_VREFEN | ADC_CCR_VBATEN);
+
+	uint16_t vbat_raw = (ADC_FULL_SCALE * VREFINT_CAL * vbat * 2 / (vrefint * ((1<<12)-1)));
+	if (vbat_raw < 100) {
+		// maybe D2 is not installed
+		return -1;
+	}
+	
+	return vbat_raw + VBAT_DIODE_VF;
+
+}
+
 void adc_start_analog_watchdogd(ADC_TypeDef *adc, uint32_t chsel)
 {
   uint32_t cfgr1;

main.c

@@ -52,6 +52,7 @@ int8_t sweep_enabled = TRUE;
 int8_t cal_auto_interpolate = TRUE;
 int8_t redraw_requested = FALSE;
 int8_t stop_the_world = FALSE;
+int16_t vbat = 0;
 
 static THD_WORKING_AREA(waThread1, 640);
 static THD_FUNCTION(Thread1, arg)
@@ -74,6 +75,13 @@ static THD_FUNCTION(Thread1, arg)
         ui_process();
       }
 
+      if (vbat != -1) {
+          adc_stop(ADC1);
+          vbat = adc_vbat_read(ADC1);
+          touch_start_watchdog();
+          draw_battery_status();
+      }
+
       /* calculate trace coordinates */
       plot_into_index(measured);
       /* plot trace as raster */
@@ -1742,6 +1750,13 @@ static void cmd_version(BaseSequentialStream *chp, int argc, char *argv[])
   chprintf(chp, "%s\r\n", NANOVNA_VERSION);
 }
 
+static void cmd_vbat(BaseSequentialStream *chp, int argc, char *argv[])
+{
+  (void)argc;
+  (void)argv;
+  chprintf(chp, "%d mV\r\n", vbat);
+}
+
 static THD_WORKING_AREA(waThread2, /* cmd_* max stack size + alpha */410);
 
 static const ShellCommand commands[] =
@@ -1779,6 +1794,7 @@ static const ShellCommand commands[] =
     { "marker", cmd_marker },
     { "edelay", cmd_edelay },
     { "capture", cmd_capture },
+    { "vbat", cmd_vbat },
     { NULL, NULL }
 };
 

nanovna.h

@@ -194,6 +194,7 @@ void set_trace_refpos(int t, float refpos);
 float get_trace_scale(int t);
 float get_trace_refpos(int t);
 const char *get_trace_typename(int t);
+void draw_battery_status(void);
 
 void set_electrical_delay(float picoseconds);
 float get_electrical_delay(void);
@@ -230,6 +231,7 @@ void marker_position(int m, int t, int *x, int *y);
 int search_nearest_index(int x, int y, int t);
 
 extern int8_t redraw_requested;
+extern int16_t vbat;
 
 /*
  * ili9341.c
@@ -350,10 +352,21 @@ uint16_t adc_single_read(ADC_TypeDef *adc, uint32_t chsel);
 void adc_start_analog_watchdogd(ADC_TypeDef *adc, uint32_t chsel);
 void adc_stop(ADC_TypeDef *adc);
 void adc_interrupt(ADC_TypeDef *adc);
+int16_t adc_vbat_read(ADC_TypeDef *adc);
 
 /*
  * misclinous
  */
 #define PULSE do { palClearPad(GPIOC, GPIOC_LED); palSetPad(GPIOC, GPIOC_LED);} while(0)
 
+// convert vbat [mV] to battery indicator
+static inline uint8_t vbat2bati(int16_t vbat)
+{
+	if (vbat < 3200) return 0;
+	if (vbat < 3450) return 25;
+	if (vbat < 3700) return 50;
+	if (vbat < 4100) return 75;
+	return 100;
+}
+
 /*EOF*/

plot.c

@@ -1484,6 +1484,76 @@ draw_cal_status(void)
   }
 }
 
+void
+draw_battery_status(void)
+{
+    int w = 10, h = 14;
+    int x = 0, y = 0;
+    int i, c;
+    uint16_t *buf = spi_buffer;
+    uint8_t vbati = vbat2bati(vbat);
+    uint16_t col = vbati == 0 ? RGB565(0, 255, 0) : RGB565(0, 0, 240);
+    memset(spi_buffer, 0, w * h * 2);
+
+    // battery head
+    x = 3;
+    buf[y * w + x++] = col;
+    buf[y * w + x++] = col;
+    buf[y * w + x++] = col;
+    buf[y * w + x++] = col;
+
+    y++;
+    x = 3;
+    buf[y * w + x++] = col;
+    x++; x++;
+    buf[y * w + x++] = col;
+
+    y++;
+    x = 1;
+    for (i = 0; i < 8; i++)
+        buf[y * w + x++] = col;
+
+    for (c = 0; c < 3; c++) {
+        y++;
+        x = 1;
+        buf[y * w + x++] = col;
+        x++; x++; x++; x++; x++; x++;
+        buf[y * w + x++] = col;
+
+        y++;
+        x = 1;
+        buf[y * w + x++] = col;
+        x++;
+        for (i = 0; i < 4; i++)
+            buf[y * w + x++] = ( ((c+1) * 25) >= (100 - vbati)) ? col : 0;
+        x++;
+        buf[y * w + x++] = col;
+
+        y++;
+        x = 1;
+        buf[y * w + x++] = col;
+        x++;
+        for (i = 0; i < 4; i++)
+            buf[y * w + x++] = ( ((c+1) * 25) >= (100 - vbati)) ? col : 0;
+        x++;
+        buf[y * w + x++] = col;
+    }
+
+    // battery foot
+    y++;
+    x = 1;
+    buf[y * w + x++] = col;
+    x++; x++; x++; x++; x++; x++;
+    buf[y * w + x++] = col;
+
+    y++;
+    x = 1;
+    for (i = 0; i < 8; i++)
+        buf[y * w + x++] = col;
+
+    ili9341_bulk(0, 1, w, h);
+}
+
 void
 request_to_redraw_grid(void)
 {