CC3D - Add support for battery voltage monitoring on S5_IN.

See docs for further details.

docs/Battery.md

@@ -0,0 +1,57 @@
+# Battery Monitoring
+
+Cleanflight has battery monitoring capability.  Battery voltage of the main battery can be measured by the system and used
+to trigger a low-battery warning buzzer, on-board status LED flashing and LED strip patterns.
+
+Low battery warnings can:
+
+* help to ensure that you have time to safely land the aircraft.
+* help maintain the life and safety of your LiPo/LiFe batteries which should not be discharged below manufactures recommendations.
+
+Minimum and maximum cell voltages can be set, these voltages are used to detect the amount of cells you are using.
+
+Per-cell monitoring is not supported.
+  
+## Supported targets
+
+All targets support battery voltage monitoring unless status.
+
+## Connections
+
+When dealing with batteries ALWAYS CHECK POLARITY!
+
+Measure expected voltages first and then connect to flight controller, connecting to the flight controller with
+incorrect voltage or reversed polarity will likely fry your flight controller.
+
+### Naze32
+
+The Naze32 has an on-board battery divider circuit, connect your main battery to the VBAT connector.
+
+### CC3D
+
+The CC3D has no battery divider, create one that gives you a 3.3v MAXIMUM output when your battery is
+fully charged and connect the output from it to S5_IN/PA0/RC5.
+
+S5_IN/PA0/RC5 is Pin 7 on the 8 pin connector, second to last pin, opposite end from the GND/+5/PPM signal input.
+
+Note: When battery monitoring is enabled on the CC3D RC5 can no-longer be used for PWM input.
+ 
+## Configuration
+
+Enable the `VBAT` feature.
+
+Configure min/max cell voltages using the following CLI commands:
+
+`vbat_scale` - adjust this to match battery voltage to reported value.
+
+`vbat_max_cell_voltage` - maximum voltage per cell, used for auto-detecting battery voltage in 0.1V units, i.e. 43 = 4.3V
+
+`vbat_min_cell_voltage` - minimum voltage per cell, this triggers battery out alarms, in 0.1V units, i.e. 33 = 3.3V
+
+e.g.
+
+```
+set vbat_scale = 110
+set vbat_max_cell_voltage = 43
+set vbat_min_cell_voltage = 33
+```

src/main/drivers/adc.c

@@ -32,7 +32,7 @@ extern int16_t debug[4];
 
 uint16_t adcGetChannel(uint8_t channel)
 {
-#if 0
+#if DEBUG_ADC_CHANNELS
     if (adcConfig[0].enabled) {
         debug[0] = adcValues[adcConfig[0].dmaIndex];
     }

src/main/drivers/adc_stm32f10x.c

@@ -33,22 +33,24 @@
 
 // Driver for STM32F103CB onboard ADC
 //
+// Naze32
 // Battery Voltage (VBAT) is connected to PA4 (ADC1_IN4) with 10k:1k divider
 // RSSI ADC uses CH2 (PA1, ADC1_IN1)
 // Current ADC uses CH8 (PB1, ADC1_IN9)
 //
 // NAZE rev.5 hardware has PA5 (ADC1_IN5) on breakout pad on bottom of board
+//
+// CC3D Only one ADC channel supported currently, for battery on S5_IN/PA0
 
 extern adc_config_t adcConfig[ADC_CHANNEL_COUNT];
 extern volatile uint16_t adcValues[ADC_CHANNEL_COUNT];
 
-#ifdef CC3D
-void adcInit(drv_adc_config_t *init) {
-    UNUSED(init);
-}
-#else
 void adcInit(drv_adc_config_t *init)
 {
+#ifdef CC3D
+    UNUSED(init);
+#endif
+
     ADC_InitTypeDef adc;
     DMA_InitTypeDef dma;
     GPIO_InitTypeDef GPIO_InitStructure;
@@ -59,10 +61,19 @@ void adcInit(drv_adc_config_t *init)
     memset(&adcConfig, 0, sizeof(adcConfig));
 
     GPIO_StructInit(&GPIO_InitStructure);
-    GPIO_InitStructure.GPIO_Pin   = GPIO_Pin_4;
     GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AIN;
 
+#ifdef CC3D
+    UNUSED(init);
+    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
+    adcConfig[ADC_BATTERY].adcChannel = ADC_Channel_0;
+    adcConfig[ADC_BATTERY].dmaIndex = configuredAdcChannels++;
+    adcConfig[ADC_BATTERY].enabled = true;
+    adcConfig[ADC_BATTERY].sampleTime = ADC_SampleTime_239Cycles5;
+    GPIO_Init(GPIOA, &GPIO_InitStructure);
+#else
     // configure always-present battery index (ADC4)
+    GPIO_InitStructure.GPIO_Pin   = GPIO_Pin_4;
     adcConfig[ADC_BATTERY].adcChannel = ADC_Channel_4;
     adcConfig[ADC_BATTERY].dmaIndex = configuredAdcChannels++;
     adcConfig[ADC_BATTERY].enabled = true;
@@ -109,6 +120,7 @@ void adcInit(drv_adc_config_t *init)
         adcConfig[ADC_CURRENT].enabled = true;
         adcConfig[ADC_CURRENT].sampleTime = ADC_SampleTime_239Cycles5;
     }
+#endif // !CC3D
 
     RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);
     RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
@@ -156,4 +168,3 @@ void adcInit(drv_adc_config_t *init)
 
     ADC_SoftwareStartConvCmd(ADC1, ENABLE);
 }
-#endif

src/main/drivers/pwm_mapping.c

@@ -326,6 +326,11 @@ pwmOutputConfiguration_t *pwmInit(drv_pwm_config_t *init)
             continue;
 #endif
 
+#ifdef CC3D
+        if (init->useVbat && timerIndex == PWM5) {
+            continue;
+        }
+#endif
         // hacks to allow current functionality
         if (type == MAP_TO_PWM_INPUT && !init->useParallelPWM)
             type = 0;

src/main/drivers/pwm_mapping.h

@@ -42,6 +42,7 @@ typedef struct drv_pwm_config_t {
 #ifdef STM32F10X
     bool useUART2;
 #endif
+    bool useVbat;
     bool useSoftSerial;
     bool useLEDStrip;
     bool useServos;

src/main/main.c

@@ -197,6 +197,7 @@ void init(void)
     }
 #endif
 
+    pwm_params.useVbat = feature(FEATURE_VBAT);
     pwm_params.useSoftSerial = feature(FEATURE_SOFTSERIAL);
     pwm_params.useParallelPWM = feature(FEATURE_RX_PARALLEL_PWM);
     pwm_params.useRSSIADC = feature(FEATURE_RSSI_ADC);