diff --git a/application.c b/application.c
index 3d7f3cc..6b85c86 100644
--- a/application.c
+++ b/application.c
@@ -529,7 +529,7 @@ static void command_connections(void* argument)
 
 	printf("= checking all pin connections =\n");
 	uint16_t connections_nb = 0;
-	uint8_t (*connections)[2] = (uint8_t (*)[2])usb_cables_check_connections(usb_connectors, LENGTH(usb_connectors), &connections_nb);
+	uint8_t (*connections)[2] = (uint8_t (*)[2])usb_cables_check_connections(usb_connectors, LENGTH(usb_connectors), true, false, &connections_nb);
 	if (NULL == connections) {
 		if (connections_nb) {
 			printf("no memory available\n");
diff --git a/usb_cables.c b/usb_cables.c
index a729824..f68ea4d 100644
--- a/usb_cables.c
+++ b/usb_cables.c
@@ -4938,7 +4938,7 @@ bool usb_cables_check_cable(const struct usb_cable_t* cable, uint8_t* defined, u
 	return (0 == _undefined && cable->pin_pairs_nb == _defined);
 }
 
-uint8_t** usb_cables_check_connections(const struct usb_connector_t** connectors, uint8_t connectors_nb, uint16_t* connections_nb)
+uint8_t** usb_cables_check_connections(const struct usb_connector_t** connectors, uint8_t connectors_nb, bool include_intra, bool ground_only, uint16_t* connections_nb)
 {
 	*connections_nb = 0; // number of connections between the connectors we found
 	uint8_t (*connections)[2] = NULL; // connections between the connectors we found (pairs of pin index)
@@ -4959,7 +4959,13 @@ uint8_t** usb_cables_check_connections(const struct usb_connector_t** connectors
 				continue;
 			}
 			const struct usb_pin_t* usb_pin_from = &usb_pins[pin_from]; // get from pin
+			if (ground_only && USB_PIN_TYPE_GROUND != usb_pin_from->type) { // enforce ground only rule
+				continue;
+			}
 			for (uint8_t connector_to_i = connector_from_i; connector_to_i < connectors_nb; connector_to_i++) { // test to every connector (yet untested)
+				if (!include_intra && connector_to_i == connector_from_i) { // don't check internal connections
+					continue;
+				}
 				const struct usb_connector_t* connector_to = connectors[connector_to_i]; // get connector
 				if (NULL == connector_to) {
 					continue;
@@ -4986,6 +4992,9 @@ uint8_t** usb_cables_check_connections(const struct usb_connector_t** connectors
 					if (USB_PIN_TYPE_POWER == usb_pin_from->type && (USB_PIN_TYPE_GROUND == usb_pin_to->type || USB_PIN_TYPE_SHIELD == usb_pin_to->type)) {
 						continue;
 					}
+					if (ground_only && USB_PIN_TYPE_GROUND != usb_pin_to->type) { // enforce ground only rule
+						continue;
+					}
 
 					// test connection
 					uint8_t connection = usb_cables_check_pins(usb_pin_from, usb_pin_to);
diff --git a/usb_cables.h b/usb_cables.h
index ab44c56..f507062 100644
--- a/usb_cables.h
+++ b/usb_cables.h
@@ -133,8 +133,10 @@ bool usb_cables_check_cable(const struct usb_cable_t* cable, uint8_t* defined, u
 /** check connections between connectors
  *  @param[in] connectors connectors to check
  *  @param[in] connectors_nb numbers of connectors
+ *  @param[in] include_intra if connections between pins within a connector should be checked
+ *  @param[in] ground_only only check connections between ground pins
  *  @param[out] connections_nb number of connections found
  *  @return list of pin pairs connections (NULL if 0 connections have been found or no connections have been found but no memory is available)
  *  @the list of pin pairs connections is allocated memory which should be freed by the caller
  */
-uint8_t** usb_cables_check_connections(const struct usb_connector_t** connectors, uint8_t connectors_nb, uint16_t* connections_nb);
+uint8_t** usb_cables_check_connections(const struct usb_connector_t** connectors, uint8_t connectors_nb, bool include_intra, bool ground_only, uint16_t* connections_nb);