USB-MIDI converters can connect to multiple Embedded MIDI Jacks. Each MIDI Endpoint in a USB-MIDI
converter can be connected to up to 16 Embedded MIDI Jacks. Each Embedded MIDI Jack connected to one
MIDI Endpoint is assigned a number from 0 to 15. MIDI Data is transferred over the USB in 32-bit USBMIDI
Event Packets, with the first 4 bits used to designate the appropriate Embedded MIDI Jack.
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void usbsend(unsigned char note, unsigned char velo) {
while (!usbInterruptIsReady()) {
wdt_reset();
usbPoll();
}
midiMsg[0] = 0x09;
midiMsg[1] = MIDI_NOTEON|MIDI_CHAN;
midiMsg[2] = note;
midiMsg[3] = velo;
midiMsg[4] = 0x08;
midiMsg[5] = MIDI_NOTEOFF|MIDI_CHAN;
midiMsg[6] = note;
midiMsg[7] = 0;
sendEmptyFrame = 1;
usbSetInterrupt(midiMsg, 8);
}
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void usbsend(unsigned char first_note, unsigned char first_velo, unsigned char second_note, unsigned char second_velo) {
while (!usbInterruptIsReady()) {
wdt_reset();
usbPoll();
}
midiMsg[0] = 0x09;
midiMsg[1] = MIDI_NOTEON|MIDI_CHAN;
midiMsg[2] = first_note;
midiMsg[3] = first_velo;
midiMsg[4] = 0x09;
midiMsg[5] = MIDI_NOTEON|MIDI_CHAN;
midiMsg[6] = second_note;
midiMsg[7] = second_velo;
sendEmptyFrame = 1;
usbSetInterrupt(midiMsg, 8);
}
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/* Name: main.c
* ...
*/
// ...
// B.5 Bulk OUT Endpoint Descriptors
//B.5.1 Standard Bulk OUT Endpoint Descriptor
9, /* bLenght */
USBDESCR_ENDPOINT, /* bDescriptorType = endpoint */
0x1, /* bEndpointAddress OUT endpoint number 1 */
2, /* bmAttributes: 2:Bulk, 3:Interrupt endpoint <=== CHANGE HERE TO BULK */
8, 0, /* wMaxPacketSize */
10, /* bIntervall in ms */
0, /* bRefresh */
0, /* bSyncAddress */
// B.5.2 Class-specific MS Bulk OUT Endpoint Descriptor
5, /* bLength of descriptor in bytes */
37, /* bDescriptorType */
1, /* bDescriptorSubtype */
1, /* bNumEmbMIDIJack */
1, /* baAssocJackID (0) */
//B.6 Bulk IN Endpoint Descriptors
//B.6.1 Standard Bulk IN Endpoint Descriptor
9, /* bLenght */
USBDESCR_ENDPOINT, /* bDescriptorType = endpoint */
0x81, /* bEndpointAddress IN endpoint number 1 */
2, /* bmAttributes: 2: Bulk, 3: Interrupt endpoint <=== CHANGE HERE TO BULK */
8, 0, /* wMaxPacketSize */
10, /* bIntervall in ms */
0, /* bRefresh */
0, /* bSyncAddress */
// B.6.2 Class-specific MS Bulk IN Endpoint Descriptor
5, /* bLength of descriptor in bytes */
37, /* bDescriptorType */
1, /* bDescriptorSubtype */
1, /* bNumEmbMIDIJack (0) */
3, /* baAssocJackID (0) */
};
// ...
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[ 8848.352583] usb 1-2: new low speed USB device using uhci_hcd and address 14
[ 8848.456365] usb 1-2: config 1 interface 1 altsetting 0 endpoint 0x1 is Bulk; changing to Interrupt
[ 8848.456379] usb 1-2: config 1 interface 1 altsetting 0 endpoint 0x81 is Bulk; changing to Interrupt
[ 8848.473328] usb 1-2: configuration #1 chosen from 1 choice
Consumes 90% or more of the AVR's CPU time because bulk endpoints are polled aggressively by the host. Real-time applications on the AVR are close to impossible.
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for (;;) {
PORTD ^= 0x80;
wdt_reset();
usbPoll();
}
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for (;;) {
PORTD ^= 0x80;
wdt_reset();
usbPoll();
usbSetInterrupt(midiMsg, 8);
}
psc wrote:...
There's something i am wondering:Consumes 90% or more of the AVR's CPU time because bulk endpoints are polled aggressively by the host. Real-time applications on the AVR are close to impossible.
Since we are now using bulk endpoint (are we?) is this a concern for us?
...
Patrick
Code: Select all
[ 8848.456365] usb 1-2: config 1 interface 1 altsetting 0 endpoint 0x1 is Bulk; changing to Interrupt
[ 8848.456379] usb 1-2: config 1 interface 1 altsetting 0 endpoint 0x81 is Bulk; changing to InterruptCode: Select all
bmAttributes=3 (interrupt), bIntervall=2 
Any Mac users around 
