update README with mock connector instructions

README.md

@@ -74,6 +74,19 @@ You can see all data sent to it in a string format with this command:
 $ ros2 topic echo /anchor/to_vic/debug
 ```
 
+To send data to it, use the normal topic:
+
+```bash
+$ ros2 topic pub /anchor/to_vic/relay astra_msgs/msg/VicCAN '{mcu_name: "core", command_id: 50, data: [0.0, 2.0, 0.0, 1.0]}'
+
+```
+
+To emulate receiving data from a microcontroller, publish to the dedicated topic:
+
+```bash
+$ ros2 topic pub /anchor/from_vic/mock_mcu std_msgs/msg/String '{data: "can_relay_fromvic,arm,55,0.0,450.0,900.0,0.0"}'
+```
+
 ### Testing Serial
 
 You can fake the presence of a Serial device (i.e., MCU) by using the following command:

src/anchor_pkg/anchor_pkg/anchor_node.py

@@ -42,6 +42,9 @@ class Anchor(Node):
         - Core, Arm, and Bio publish VicCAN messages to this topic to send to the MCU
     * /anchor/to_vic/relay_string
         - Send raw strings to connectors. Does not work for connectors that require conversion (like CANConnector)
+    * /anchor/relay
+        - Legacy method for talking to connectors. Takes String as input, but does not send the raw strings to connectors.
+          Instead, it converts them to VicCAN messages first.
     """
 
     connector: Connector
@@ -203,7 +206,7 @@ class Anchor(Node):
         self.connector.write(msg)
         self.tovic_debug_pub_.publish(msg)
 
-    @deprecated("Use /anchor/to_vic/relay instead of /anchor/relay")
+    @deprecated("Use /anchor/to_vic/relay or /anchor/to_vic/relay_string instead of /anchor/relay")
     def write_connector_legacy(self, msg: String):
         """Write to the connector by first attempting to convert String to VicCAN"""
         # please do not reference this code. ~riley

src/anchor_pkg/anchor_pkg/connector.py

@@ -372,8 +372,10 @@ class CANConnector(Connector):
             case 2:
                 data_type = 1
                 data = struct.pack(">ff", *msg.data)
-            case 4:
+            case 3 | 4: # 3 gets padded and is treated as 4
                 data_type = 2
+                # pad till we have 4 otherwise struct.pack will freak out
+                msg.data = (msg.data + [0])[:4]
                 data = struct.pack(">hhhh", *[int(x) for x in msg.data])
             case _:
                 self.logger.error(

src/anchor_pkg/anchor_pkg/convert.py

@@ -57,6 +57,8 @@ def string_to_viccan(
 
 def viccan_to_string(viccan: VicCAN) -> str:
     """Converts a ROS2 VicCAN message to the serial string VicCAN format."""
+    # make sure we accept 3 digits and treat it as 4
+    if len(viccan.data) == 3: viccan.data.append("0")
     # go from [ w, x, y, z ] -> ",w,x,y,z" & round to 7 digits max
     data = "".join([f",{round(val,7)}" for val in viccan.data])
     return f"can_relay_tovic,{viccan.mcu_name},{viccan.command_id}{data}\n"