Clarify MCP2515 pumpEvents

Author: solomondg

examples/SineWaveCAN/SineWaveCAN.ino

@@ -244,6 +244,9 @@ void setup() {
 
 void loop() {
   pumpEvents(can_intf); // This is required on some platforms to handle incoming feedback CAN messages
+                        // Note that on MCP2515-based platforms, this will delay for a fixed 10ms.
+                        // This has been found to reduce the number of dropped messages, however it can be removed
+                        // for applications requiring loop times over 100Hz.
 
   float SINE_PERIOD = 2.0f; // Period of the position command sine wave in seconds
 

src/ODriveMCPCAN.hpp

@@ -33,9 +33,12 @@ static void onReceive(const CanMsg& msg, ODriveCAN& odrive) {
 }
 
 static void pumpEvents(MCP2515Class& intf) {
-    // nothing to do
-    // TODO: maybe remove
-    delay(10); // not sure why this resulted in less dropped messages, could have been a twisted coincidence
+    // On other platforms, this polls and processes incoming CAN messages.
+    // However, this is not possible on MCP2515-based platforms.
+
+    // A 10ms delay was found to reduce the number of dropped messages, however a
+    // specific root cause has not been identified, and may be a quirk in the MCP2515.
+    delay(10);
 }
 
 CREATE_CAN_INTF_WRAPPER(MCP2515Class)