stm32f4: adc: Add VBat sensor enable/disable

Original discussion at: https://github.com/libopencm3/libopencm3/pull/770

2 files changed, 20 insertions, 2 deletions

diff --git a/include/libopencm3/stm32/f4/adc.h b/include/libopencm3/stm32/f4/adc.h
index 7e5c1c8d..6907425d 100644
--- a/include/libopencm3/stm32/f4/adc.h
+++ b/include/libopencm3/stm32/f4/adc.h
@@ -579,9 +579,10 @@ void adc_eoc_after_each(uint32_t adc);
 void adc_eoc_after_group(uint32_t adc);
 void adc_set_dma_continue(uint32_t adc);
 void adc_set_dma_terminate(uint32_t adc);
-
 void adc_enable_temperature_sensor(void);
 void adc_disable_temperature_sensor(void);
+void adc_enable_vbat_sensor(void);
+void adc_disable_vbat_sensor(void);
 
 END_DECLS
 
diff --git a/lib/stm32/f4/adc.c b/lib/stm32/f4/adc.c
index aaa0a5c7..020db884 100644
--- a/lib/stm32/f4/adc.c
+++ b/lib/stm32/f4/adc.c
@@ -426,6 +426,23 @@ void adc_disable_temperature_sensor(void)
 	ADC_CCR &= ~ADC_CCR_TSVREFE;
 }
 
-/*---------------------------------------------------------------------------*/
+/** Enable The VBat Sensor.
+ * This enables the battery voltage measurements on ADC1 channel 18. On
+ * STM32F42x and STM32F43x, this must be disabled when the temperature sensor
+ * is enabled. If both are enabled, only the VBat conversion is performed.
+ */
+void adc_enable_vbat_sensor(void)
+{
+	ADC_CCR |= ADC_CCR_VBATE;
+}
+
+/** Disable The VBat Sensor.
+ * Disabling this will reduce power consumption from the battery voltage
+ * measurement.
+ */
+void adc_disable_vbat_sensor(void)
+{
+	ADC_CCR &= ~ADC_CCR_VBATE;
+}
 
 /**@}*/