drivers/foc: support for BEMF sensing

arch/arm/src/stm32/stm32_foc.c

@@ -1717,7 +1717,11 @@ static int stm32_foc_worker_handler(struct foc_dev_s *dev)
 
       /* Call upper-half worker callback */
 
-      priv->cb->notifier(dev, priv->data.curr);
+#ifdef CONFIG_MOTOR_FOC_BEMF_SENSE
+#  error BEMF sensing not supported yet
+#else
+      priv->cb->notifier(dev, priv->data.curr, NULL);
+#endif
     }
 
   return ret;

arch/arm/src/stm32f7/stm32_foc.c

@@ -1507,7 +1507,11 @@ static int stm32_foc_worker_handler(struct foc_dev_s *dev)
 
       /* Call upper-half worker callback */
 
-      priv->cb->notifier(dev, priv->data.curr);
+#ifdef CONFIG_MOTOR_FOC_BEMF_SENSE
+#  error BEMF sensing not supported yet
+#else
+      priv->cb->notifier(dev, priv->data.curr, NULL);
+#endif
     }
 
   return ret;

drivers/motor/foc/Kconfig

@@ -22,6 +22,10 @@ config MOTOR_FOC_SHUNTS
 		Number of shunts supported (or other types of current sensors).
 		Any current reconstruction must be done on the lower-half side.
 
+config MOTOR_FOC_BEMF_SENSE
+	bool "FOC support for Back-EMF sensing"
+	default n
+
 config MOTOR_FOC_TRACE
 	bool "FOC trace support"
 	default n

drivers/motor/foc/foc_dev.c

@@ -62,7 +62,8 @@ static int foc_info_get(FAR struct foc_dev_s *dev,
                         FAR struct foc_info_s *info);
 
 static int foc_notifier(FAR struct foc_dev_s *dev,
-                        FAR foc_current_t *current);
+                        FAR foc_current_t *current,
+                        FAR foc_voltage_t *voltage);
 
 /****************************************************************************
  * Private Data
@@ -726,7 +727,8 @@ static int foc_info_get(FAR struct foc_dev_s *dev,
  ****************************************************************************/
 
 static int foc_notifier(FAR struct foc_dev_s *dev,
-                        FAR foc_current_t *current)
+                        FAR foc_current_t *current,
+                        FAR foc_voltage_t *voltage)
 {
   int ret  = OK;
   int sval = 0;
@@ -743,6 +745,18 @@ static int foc_notifier(FAR struct foc_dev_s *dev,
          current,
          sizeof(foc_current_t) * CONFIG_MOTOR_FOC_PHASES);
 
+#ifdef CONFIG_MOTOR_FOC_BEMF_SENSE
+  /* Copy voltage */
+
+  memcpy(&dev->state.volt,
+         voltage,
+         sizeof(foc_voltage_t) * CONFIG_MOTOR_FOC_PHASES);
+#else
+  /* If BEMF sampling is not enabled then voltage must be NULL */
+
+  DEBUGASSERT(voltage == NULL);
+#endif
+
   /* Check if the previous cycle was handled */
 
   ret = nxsem_get_value(&dev->statesem, &sval);

drivers/motor/foc/foc_dummy.c

@@ -79,6 +79,12 @@ struct foc_dummy_data_s
 
   foc_current_t current[CONFIG_MOTOR_FOC_PHASES];
 
+#ifdef CONFIG_MOTOR_FOC_BEMF_SENSE
+  /* BEMF voltage */
+
+  foc_voltage_t volt[CONFIG_MOTOR_FOC_PHASES];
+#endif
+
   /* FOC worker loop helpers */
 
   bool     state;
@@ -464,7 +470,11 @@ static void foc_dummy_notifier_handler(FAR struct foc_dev_s *dev)
     {
       /* Call FOC notifier */
 
-      sim->cb->notifier(dev, sim->current);
+#ifdef CONFIG_MOTOR_FOC_BEMF_SENSE
+      sim->cb->notifier(dev, sim->current, sim->voltage);
+#else
+      sim->cb->notifier(dev, sim->current, NULL);
+#endif
     }
 
   /* Increase counter */

include/nuttx/motor/foc/foc.h

@@ -60,9 +60,10 @@ enum foc_fault_e
   FOC_FAULT_BOARD   = (1 << 3), /* Board-specific fault */
 };
 
-/* Phase current as signed 32-bit integer */
+/* Phase current and BEMF voltage as signed 32-bit integer */
 
 typedef int32_t foc_current_t;
+typedef int32_t foc_voltage_t;
 
 /* Phase duty cycle as unsigned fixed16.
  * We use range [0.0 to 1.0] so this gives us a 16-bit resolution.
@@ -84,6 +85,9 @@ struct foc_state_s
 {
   uint8_t       fault;                         /* Fault state */
   foc_current_t curr[CONFIG_MOTOR_FOC_PHASES]; /* Phase current feedback */
+#ifdef CONFIG_MOTOR_FOC_BEMF_SENSE
+  foc_voltage_t volt[CONFIG_MOTOR_FOC_PHASES]; /* BEMF voltage feedback */
+#endif
 };
 
 /* Input data to the FOC device */

include/nuttx/motor/foc/foc_lower.h

@@ -77,13 +77,15 @@ struct foc_callbacks_s
   /* FOC notifier callback
    *
    * Description:
-   *   Deliver the phase current samples and wake up the thread waiting.
-   *   Must be called by lower-half logic at a frequency determined by
-   *   configuration (notifier_freq in foc_cfg_s).
+   *   Deliver the phase current samples (and optional BEMF voltages)
+   *   and wake up the thread waiting. Must be called by lower-half
+   *   logic at a frequency determined by configuration (notifier_freq
+   *   in foc_cfg_s).
    */
 
   CODE int (*notifier)(FAR struct foc_dev_s *dev,
-                       FAR foc_current_t *current);
+                       FAR foc_current_t *current,
+                       FAR foc_voltage_t *voltage);
 };
 
 /* Lower-half FOC operations */