SysEx msg byte 0xF7 not being read correctly

[bossredman]

Hi,

I've seen mentions of similar issues in earlier versions of the Midi Library (ie pre-v4.2) where F7's (ie msg terminating byte) were being read as 0's.
But that in v4.2 + it was fixed.

I now also seeing this issue but its not just with converting to 0.
I'm also seeing other values too.

I'm running a Teensy 3.6 with: Arduino IDE (v1.6.12) / Teensyduino (v1.31) / midi library v4.3.1.
Project is a midi foot controller for AxeFX2.

I've just noticed this whilst looking into another issue (ref: "Errors trying to override Max SysEx message length #66") https://github.com/FortySevenEffects/arduino_midi_library/issues/66

[franky47]

Do you have an example message that was received incorrectly (but somehow parsed correctly as a SysEx message ?)

[bossredman]

Here's one for the Preset Number - in this case it was preset 4.

++++ PRESET-NUMBER SYSEX - 0x14 +++++
4
0 = F0
1 = 0
2 = 1
3 = 74
4 = 3
5 = 14
6 = 0
7 = 4
8 = 16
9 = 46

Response format (from Axefx Wiki):

0xF0 sysex start 
0x00 Manf. ID byte0 
0x01 Manf. ID byte1 
0x74 Manf. ID byte2 
0x03 Model # 
0x14 Function ID (0x14) 
0xdd Preset Number bits 6-0 
0xdd Preset Number bits 13-7 
0xdd checksum 
0xF7 sysex end 

[bossredman]

..and also one for Preset name - in this case "Stone Roses":

      ++++ PRESET-NAME SYSEX - 0x0f  +++++
           Stone Roses         

0 = F0
1 = 0
2 = 1
3 = 74
4 = 3
5 = F
6 = 53
7 = 74
8 = 6F
9 = 6E
10 = 65
11 = 20
12 = 52
13 = 6F
14 = 73
15 = 65
16 = 73
17 = 20
18 = 20
19 = 20
20 = 20
21 = 20
22 = 20
23 = 20
24 = 20
25 = 20
26 = 20
27 = 20
28 = 20
29 = 20
30 = 20
31 = 20
32 = 20
33 = 20
34 = 20
35 = 20
36 = 0
37 = 0
38 = 12
39 = 33

Response format:

0xF0 sysex start 
0x00 Manf. ID byte0 
0x01 Manf. ID byte1 
0x74 Manf. ID byte2 
0x03 Model # 
0x0F Function ID (0x0F) 
0xdd null-terminated string byte0 
0xdd byte1 
... 
0x00 null character 
0xdd checksum 
0xF7 sysex end 

[franky47]

Thanks, so you definitely get a SysEx response from the library (MIDI.read() returns true and MIDI.getMessageType() == midi::SysEx, or end up in a handleSysEx callback), and your buffer looks like this ?

If you get the message recognized as SysEx, and as there is no particular way of knowing a generic SysEx length other than waiting for 0xF7, it means it was correctly received, but somehow dropped by the parser. I'll run some tests and I'll get back to you.

[bossredman]

Ref

and your buffer looks like this ?

They were copies from the serial monitor output.
FYI - Here's my code that gets them.

//Gets called if a SysEx msg is recieved after the MIDI.read() command is called.
void HandleSystemExclusive(byte *SysExArray, byte arraySize)     
{
    if (SysExArray[5] == 0x14)          //If Read a Preset Number Sysex
    {
        int sizear = MIDI.getSysExArrayLength();

        Serial.println("          ++++ PRESET-NUMBER SYSEX - 0x14  +++++");
        BANK = (MIDI.getSysExArray()[6]);
        PRESET_NUM = (MIDI.getSysExArray()[7]);
        MIDI.sendSysEx(8,Preset_Name_Sysex,true);
        Serial.print("               ");
        Serial.println(PRESET_NUM);
        for (int v = 0; v < sizear; v++)
        {
            Serial.print(v);
            Serial.print("  =  ");
            Serial.println(SysExArray[v], HEX);
        }
    }

    if (SysExArray[5] == 0x0f)          //If Read a Preset Name Sysex
    {
        int sizear = MIDI.getSysExArrayLength();

        Serial.println("          ++++ PRESET-NAME SYSEX - 0x0f  +++++"); 
        for (int i = 0; i < 20; ++i)  //was 31
        {
            pname[i] = MIDI.getSysExArray()[i+6];
        }
        Setup_Compl = true;
        LCD_Print();
        Serial.print("               ");
        Serial.println(pname);

        for (int v = 0; v < sizear; v++)
        {
            Serial.print(v);
            Serial.print("  =  ");
            Serial.println(SysExArray[v], HEX);
        }  
    } 
}

[franky47]

I see you're using a byte arraySize in the callback signature, are you using an old version of the library ?

The latest version (v4.3.1) is available [here], there were a lot of bug fixes since the signature was changed to unsigned (to handle large SysEx larger than 255 bytes).

Try and update and let me know how it goes.

[bossredman]

Hi.

The resolution to issue #66 has also fixed this issue.
Looks like it was down to having muliple versions of the Midi library on my PC and my sketch kept picking up the old one.

I can now read F7's.

As you pointed out - I did have to make a further change to my code to accomodate the new version of the Library (the type of arraySize):

From: void HandleSystemExclusive(byte *SysExArray, byte arraySize)
To: void HandleSystemExclusive(byte *SysExArray, unsigned arraySize)

Cheers.