AP_ADC: added num_samples_available to allow main loop to be synced with arrival of new sensor data for Oilpan.

libraries/AP_ADC/AP_ADC.h

@@ -44,6 +44,8 @@ public:
     // check if Ch6() can return new data
     virtual bool            new_data_available(const uint8_t *channel_numbers) = 0;
 
+    virtual uint16_t        num_samples_available(const uint8_t *channel_numbers) = 0;
+
 private:
 };
 

libraries/AP_ADC/AP_ADC_ADS7844.cpp

@@ -246,3 +246,18 @@ uint32_t AP_ADC_ADS7844::Ch6(const uint8_t *channel_numbers, float *result)
     // return number of microseconds since last call
     return ret;
 }
+
+/// Get minimum number of samples read from the sensors
+uint16_t AP_ADC_ADS7844::num_samples_available(const uint8_t *channel_numbers)
+{
+    // get count of first channel as a base
+    uint16_t min_count = _count[channel_numbers[0]];
+
+    // reduce to minimum count of all other channels
+    for (uint8_t i=1; i<6; i++) {
+        if (_count[channel_numbers[i]] < min_count) {
+            min_count = _count[channel_numbers[i]];
+        }
+    }
+    return min_count;
+}

libraries/AP_ADC/AP_ADC_ADS7844.h

@@ -33,6 +33,9 @@ public:
     // check if Ch6 would block
     bool                new_data_available(const uint8_t *channel_numbers);
 
+    // Get minimum number of samples read from the sensors
+    uint16_t            num_samples_available(const uint8_t *channel_numbers);
+
 private:
     static void         read(uint32_t);
 

libraries/AP_ADC/AP_ADC_HIL.cpp

@@ -88,3 +88,9 @@ bool AP_ADC_HIL::new_data_available(const uint8_t *channel_numbers)
 {
     return true;
 }
+
+// Get minimum number of samples read from the sensors
+uint16_t AP_ADC_HIL::num_samples_available(const uint8_t *channel_numbers)
+{
+    return 1;
+}

libraries/AP_ADC/AP_ADC_HIL.h

@@ -41,6 +41,9 @@ public:
     // see if Ch6 would block
     bool            new_data_available(const uint8_t *channel_numbers);
 
+    // Get minimum number of samples read from the sensors
+    uint16_t        num_samples_available(const uint8_t *channel_numbers);
+
     ///
     // Set the adc raw values given the current rotations rates,
     // temps, accels, and pressures