MIDI Controller Message fires INT_RDA only 1 time

[zutta1]

I'm using a PIC18F4620 for a MIDI-sequenzer project.
I have a very strange problem:
The INT_RDA is fired only the first time when a stream of MIDI controller messages were received (when i turn a potentiometer on my keyboard, it sends continuous packages with the 3 Bytes statebyte+controllernumberbyte+controllerdatabyte). After that, RDA_INT will not be fired again until another message than a controller message (for example midi on: statebyte+note+velocity) is received.

[PCM programmer]

If it's not working it's possibly because:

1. The signals may be current loop compatible and not compatible with
the voltage levels required by a PIC UART input pin. They may
require an external circuit to convert them to the proper levels.

2. The input signal levels may be inverted from what you expect to see,
and may require an external circuit to invert them.

3. The input signals may not conform exactly to asynchronous serial
timing standards (start bit, number of stop bits, parity, etc).

4. The baud rate of the signals coming from the keyboard may not
really be 31250.

You need to look at the signals with an oscilloscope.
Or find the documentation for the keyboard's midi output interface
(and post a link to it).

[ckielstra]

Also try changing the line:

[zutta1]

Thank you for your answer!

I think the failure is somewhere else.

1. I use the standard circuit with optocoupler (schematic: http://www.ucapps.de/mbhp/mbhp_core_v3.pdf)


2./3. I only have the failure when the pic receives continous controller messages (3 bytes: 0xB1, controller number 0-127, controller value 0-127) or when it receives contiuous pitchbend messages (3 bytes: 0xB1, 2nd byte=0, 3rd byte=pitchbendvalue 0-127)

When i receive only note on or note off messages (3 bytes: 0xE1, note nr 0-127, velocity value 0-127) i have no problems, the sequenzer works fine.

For example the scenario n=note message, c=controller message, p=pitchbend message:

the Keyboard sends:
nnnccccccnccccc [waiting 5s] ccccccnnnppppppnccccccppppp

the pic fires the int_rda (i=int_rda) and receives the message:
in in in ic in ic in in in ip in ic ip

the pic waits till an other type of message?!


4. when i connect the keyboard over a midi interface to my computer an use a midi-monitor tool it works fine, it shows every message.


5. I have the same when i use output_toggle(LED) instead of output_bit(LED,!input(LED))


Here is the manual of the keyboard http://www.novationmusic.com/support/files/bass_station_keyboard/94/Bass_Station_keyboard_User_Guide.pdf (on page 14).

I've tried it also with a PIC18F458.

[yerpa]

It doesn't look like all of your code is represented above, but I wonder if there is a problem relating to your definition of "int rcv0" having scope only in the interrupt routine itself. Maybe it should be defined as a global or static variable. Without the rest of the code, it is hard to tell.

[zutta1]

I use the code above only to check when the int_rda is fired. Anyway, the int_rda must be fired each time a byte was received.

Here is the full sequenzer code:

[PCM programmer]

Strip the program down to a test program. Use Ex_Sisr.c as the basis
of the test program. Incoming bytes from the Midi keyboard will be
put in a buffer. In a while() loop in main(), poll to see if byte is in the
buffer. If so, get it from the buffer by using bgetc(), and display it in
ASCII hex format on your terminal program, by using "%X" in printf.

Now send some messages from the keyboard. Look at the displayed
hex bytes on the terminal window. See if they are correct. This simple
test will tell you if you can successfully do basic communication with the
keyboard. Once you have that part working, then you can do the rest
of your program.