ADC driver report back vref alone with sample count (#14136)

* Introduce "px4_arch_adc_reference_v"

* Revert "Introduce "px4_arch_adc_reference_v""

This reverts commit 93691fbbd55a1b8da8c190e225b318067d90399b.

* use structure to return sample count and vref at the same time

* Revert "use structure to return sample count and vref at the same time"

This reverts commit 9cfd1c173cda51495f766a3f678c2202d67725fd.

* Revert "Revert "Introduce "px4_arch_adc_reference_v"""

This reverts commit edb7f7603e4471163ffb0fc6fc62ad2e30336e91.

* fix missed reference

* remove unecessary channel specific vref

* Update src/drivers/drv_adc.h

Co-Authored-By: David Sidrane <David.Sidrane@Nscdg.com>

* Update src/drivers/drv_adc.h

Co-Authored-By: David Sidrane <David.Sidrane@Nscdg.com>

* Introduce BOARD_ADC_POS_REF_V

Co-authored-by: David Sidrane <David.Sidrane@Nscdg.com>

boards/aerotenna/ocpoc/adc/adc.cpp

@@ -92,6 +92,11 @@ uint32_t px4_arch_adc_sample(uint32_t base_address, unsigned channel)
 	return atoi(buffer);
 }
 
+float px4_arch_adc_reference_v()
+{
+	return BOARD_ADC_POS_REF_V;
+}
+
 uint32_t px4_arch_adc_dn_fullcount()
 {
 	return 1 << 12; // 12 bit ADC

boards/beaglebone/blue/adc/adc.cpp

@@ -92,6 +92,11 @@ uint32_t px4_arch_adc_sample(uint32_t base_address, unsigned channel)
 	return atoi(buffer);
 }
 
+float px4_arch_adc_reference_v()
+{
+	return BOARD_ADC_POS_REF_V;	// 12-bit 1.8V ADC
+}
+
 uint32_t px4_arch_adc_dn_fullcount()
 {
 	return 1 << 12; // 12 bit ADC

boards/beaglebone/blue/src/board_config.h

@@ -61,6 +61,7 @@
 
 // ADC channels:
 #define ADC_CHANNELS (1 << 5)
+#define BOARD_ADC_POS_REF_V (1.8f)
 
 #define ADC_BATTERY_VOLTAGE_CHANNEL  5
 #define ADC_BATTERY_CURRENT_CHANNEL  ((uint8_t)(-1))

boards/emlid/navio2/adc/adc.cpp

@@ -92,6 +92,11 @@ uint32_t px4_arch_adc_sample(uint32_t base_address, unsigned channel)
 	return atoi(buffer);
 }
 
+float px4_arch_adc_reference_v()
+{
+	return BOARD_ADC_POS_REF_V;
+}
+
 uint32_t px4_arch_adc_dn_fullcount()
 {
 	return 1 << 12; // 12 bit ADC

boards/emlid/navio2/src/board_config.h

@@ -73,6 +73,7 @@
 // A4 - ADC2 (ADC port)
 // A5 - ADC3 (ADC port)
 #define ADC_CHANNELS (1 << 0) | (1 << 1) | (1 << 2) | (1 << 3) | (1 << 4) | (1 << 5)
+#define BOARD_ADC_POS_REF_V (4.096f)	// TODO: need confirmation
 
 #define ADC_BATTERY_VOLTAGE_CHANNEL  2
 #define ADC_BATTERY_CURRENT_CHANNEL  3

platforms/common/include/px4_platform_common/board_common.h

@@ -147,6 +147,10 @@
 #define ADC_3V3_SCALE                    (2.0f) // The scale factor defined by HW's resistive divider (Rt+Rb)/ Rb
 #endif
 
+#ifndef BOARD_ADC_POS_REF_V
+#define BOARD_ADC_POS_REF_V              (3.3f) // Default reference voltage for every channels
+#endif
+
 #ifndef BOARD_ADC_POS_REF_V_FOR_CURRENT_CHAN
 #define BOARD_ADC_POS_REF_V_FOR_CURRENT_CHAN (3.3f) // Reference voltage for reading out the current channel
 #endif

platforms/nuttx/src/px4/nxp/imxrt/adc/adc.cpp

@@ -186,6 +186,12 @@ uint32_t px4_arch_adc_sample(uint32_t base_address, unsigned channel)
 	result  = rR0(base_address);
 	return result;
 }
+
+float px4_arch_adc_reference_v()
+{
+	return BOARD_ADC_POS_REF_V;	// TODO: provide true vref
+}
+
 uint32_t px4_arch_adc_temp_sensor_mask()
 {
 	return 0;

platforms/nuttx/src/px4/nxp/kinetis/adc/adc.cpp

@@ -176,6 +176,11 @@ uint32_t px4_arch_adc_sample(uint32_t base_address, unsigned channel)
 	return result;
 }
 
+float px4_arch_adc_reference_v()
+{
+	return BOARD_ADC_POS_REF_V;	// TODO: provide true vref
+}
+
 uint32_t px4_arch_adc_temp_sensor_mask()
 {
 	return 1 << (ADC_SC1_ADCH_TEMP >> ADC_SC1_ADCH_SHIFT);

platforms/nuttx/src/px4/nxp/s32k1xx/adc/adc.cpp

@@ -179,6 +179,11 @@ uint32_t px4_arch_adc_sample(uint32_t base_address, unsigned channel)
 	return result;
 }
 
+float px4_arch_adc_reference_v()
+{
+	return BOARD_ADC_POS_REF_V;	// TODO: provide true vref
+}
+
 uint32_t px4_arch_adc_temp_sensor_mask()
 {
 	return 1 << (ADC_SC1_ADCH_TEMP >> ADC_SC1_ADCH_SHIFT);

platforms/nuttx/src/px4/stm/stm32_common/adc/adc.cpp

@@ -224,6 +224,11 @@ uint32_t px4_arch_adc_sample(uint32_t base_address, unsigned channel)
 	return result;
 }
 
+float px4_arch_adc_reference_v()
+{
+	return BOARD_ADC_POS_REF_V;	// TODO: provide true vref
+}
+
 uint32_t px4_arch_adc_temp_sensor_mask()
 {
 	return 1 << 16;

platforms/nuttx/src/px4/stm/stm32h7/adc/adc.cpp

@@ -304,6 +304,11 @@ uint32_t px4_arch_adc_sample(uint32_t base_address, unsigned channel)
 	return result;
 }
 
+float px4_arch_adc_reference_v()
+{
+	return BOARD_ADC_POS_REF_V;	// TODO: provide true vref
+}
+
 uint32_t px4_arch_adc_temp_sensor_mask()
 {
 	return 1 << 16;

src/drivers/drv_adc.h

@@ -82,6 +82,13 @@ void px4_arch_adc_uninit(uint32_t base_address);
  */
 uint32_t px4_arch_adc_sample(uint32_t base_address, unsigned channel);
 
+/**
+ * Get the ADC positive reference voltage
+ * N.B This assume that all ADC channels share the same vref.
+ * @return v_ref
+ */
+float px4_arch_adc_reference_v(void);
+
 /**
  * Get the temperature sensor channel bitmask
  */
@@ -93,4 +100,3 @@ uint32_t px4_arch_adc_temp_sensor_mask(void);
 uint32_t px4_arch_adc_dn_fullcount(void);
 
 __END_DECLS
-