diff --git a/lib_xua/src/midi/midioutparse.h b/lib_xua/src/midi/midioutparse.h
index 9219f60b..1723b8f1 100644
--- a/lib_xua/src/midi/midioutparse.h
+++ b/lib_xua/src/midi/midioutparse.h
@@ -3,10 +3,11 @@
 #ifndef MIDIOUTPARSE_XH
 #define MIDIOUTPARSE_XH
 
-#warning MAYBE A SYSEX START AND FINISH IS SAFEST FOR NULL?
-#define MIDI_OUT_NULL_MESSAGE   0x00000000 // midi_out_parse will return a size of 0 for this invalid message/event
+// If for any reason we pop a message when not needed (should never happen) this will cause midiparse out to send a size of 0 (drops packet)
+#define MIDI_OUT_NULL_MESSAGE   0x00000000
 
 #ifdef __XC__
+// Takes a MIDI packet and decomoses it into up to 3 data bytes followed by a byte count.
 {unsigned, unsigned, unsigned, unsigned} midi_out_parse(unsigned event);
 #endif
 
diff --git a/tests/test_midi/src/app_midi_simple.xc b/tests/test_midi/src/app_midi_simple.xc
index 064dcb89..94e71079 100644
--- a/tests/test_midi/src/app_midi_simple.xc
+++ b/tests/test_midi/src/app_midi_simple.xc
@@ -134,7 +134,9 @@ void test(chanend c_midi){
                 } else {
                     unsigned midi_data[3] = {0};
                     unsigned byte_count = 0;
+                    // Even though this is an Rx from MIDI we use midi_out_parse so we can decode the packet
                     {midi_data[0], midi_data[1], midi_data[2], byte_count} = midi_out_parse(byterev(rx_packet));
+                    dprintf("Got packet from MIDI: 0x%8x\n", rx_packet);
                     // Note this needs to always print for capfd in pytest to pick it up
                     printf("dut_midi_rx: %u %u %u\n", midi_data[0], midi_data[1], midi_data[2]);
                     rx_cmd_count++;
@@ -144,9 +146,10 @@ void test(chanend c_midi){
 
             case tx_cmd_count < num_to_tx => tmr when timerafter(t_tx) :> int _:
                 unsigned midi[] = {commands[tx_cmd_count][0], commands[tx_cmd_count][1], commands[tx_cmd_count][2]};
+                // Even though this is a Tx to MIDI we use midi_in_parse_helper to form the packet from bytes
                 unsigned tx_packet = midi_in_parse_helper(midi, m_state);
                 outuint(c_midi, byterev(tx_packet));
-                dprintf("Sent packet to midi: %u %u %u\n", commands[tx_cmd_count][0], commands[tx_cmd_count][1], commands[tx_cmd_count][2]);
+                dprintf("Sent packet to midi: %u %u %u (0x%8x)\n", commands[tx_cmd_count][0], commands[tx_cmd_count][1], commands[tx_cmd_count][2], tx_packet);
                 t_tx += tx_interval;
                 tx_end += max_tx_time;
             break;
diff --git a/tests/test_midi_tx.py b/tests/test_midi_tx.py
index 5b6cfd03..9d7ed3ae 100644
--- a/tests/test_midi_tx.py
+++ b/tests/test_midi_tx.py
@@ -27,9 +27,8 @@ def test_tx(capfd, config, build_midi):
                         [0x90, 60, 81],     # Note on
                         [0x80, 60, 81]]     # Note off
 
-        # midi_command_expected = midi_commands[1:] # should skip invalid first message
-        # Make a 1D list from the 2D list
-        midi_command_expected = [[item for row in midi_commands for item in row]]
+        # Make a 1D list from the 2D list [1:] because first is invalid and we expect to skip it
+        midi_command_expected = [[item for row in midi_commands[1:] for item in row]]
 
         create_midi_tx_file(midi_commands)
         create_midi_rx_file()
@@ -42,14 +41,14 @@ def test_tx(capfd, config, build_midi):
         bpb = 8
         parity = 0 
         stop = 1
-        length_of_test = sum(len(cmd) for cmd in midi_commands)
+        length_of_test = sum(len(cmd) for cmd in midi_command_expected)
 
         simthreads = [
             UARTTxChecker(tx_port, parity, baud, length_of_test, stop, bpb, debug=False)
         ]
 
 
-        simargs = ["--max-cycles", str(MAX_CYCLES), "-o", "trace.txt"]
+        simargs = ["--max-cycles", str(MAX_CYCLES), "--trace-to", "trace.txt"]
         #This is just for local debug so we can capture the traces if needed. It slows xsim down so not needed
         # simargs.extend(["--vcd-tracing", "-tile tile[1] -ports -o trace.vcd"]) 
 
@@ -60,6 +59,7 @@ def test_tx(capfd, config, build_midi):
             timeout=120,
             simargs=simargs,   
         )
+
         capture = capfd.readouterr().out
         result = tester.run(capture.split("\n"))
 
diff --git a/tests/uart_tx_checker.py b/tests/uart_tx_checker.py
index e0476c76..c6ef7869 100644
--- a/tests/uart_tx_checker.py
+++ b/tests/uart_tx_checker.py
@@ -94,7 +94,9 @@ class UARTTxChecker(px.SimThread):
         if self.debug: print("tx starts high: %s" % ("True" if initial_port_val else "False"))
 
         for x in range(length):
-            packet.append(chr(self.read_byte(xsi, parity)))
+            byte = self.read_byte(xsi, parity)
+            if self.debug: print(f"Checker got byte: {byte}")
+            packet.append(chr(byte))
         return packet
 
     def read_byte(self, xsi, parity):