#Non-USB Notifications
Since Serial and Network (TCP) interfaces don’t intrinsicly provide an equivalent of the USB InterruptIn endpoint to send event messages on a “side channel”, notifications of card insertions and removals have to be multiplexed with the general flow of command/response messages. To simplify the implementation of the communication protocole within the host application, the RDR_To_PC_Notification message uses the same 10-B header as BulkOut/BulkIn messages (this is different from the USB specification where the InterruptIn endpoint lacks an header).
#Format of the InterruptIn messages
| Byte |
Field |
Value |
Description / Remark |
| 0 |
Endpoint |
83 |
InterruptIn |
| 1 |
Message type |
50 |
RDR_TO_PC_NOTIFYSLOTCHANGE as per CCID |
| 2-5 |
Length of payload |
00000001 or 00000002 |
Depends on the number of slots (2 bits per slot) |
| 6-10 |
|
0000000000 |
Not used |
| 11 or 11-12 |
Notification bits |
|
See below |
#Notification bits
#Byte 11
| Bits |
Field |
Values |
| 7-6 |
Status/notification for slot 3 |
00: card absent, no change since last notification
01: card present, no change since last notification
10: card removed notification
11: card inserted notification |
| 5-4 |
Status/notification for slot 2 |
00: card absent, no change since last notification
01: card present, no change since last notification
10: card removed notification
11: card inserted notification |
| 3-2 |
Status/notification for slot 1 |
00: card absent, no change since last notification
01: card present, no change since last notification
10: card removed notification
11: card inserted notification |
| 1-0 |
Status/notification for slot 0 |
00: card absent, no change since last notification
01: card present, no change since last notification
10: card removed notification
11: card inserted notification |
#Byte 12 (only for devices with 4 slots or more)
| Bits |
Field |
Values |
| 7-6 |
Status/notification for slot 7 |
00: card absent, no change since last notification
01: card present, no change since last notification
10: card removed notification
11: card inserted notification |
| 5-4 |
Status/notification for slot 6 |
00: card absent, no change since last notification
01: card present, no change since last notification
10: card removed notification
11: card inserted notification |
| 3-2 |
Status/notification for slot 5 |
00: card absent, no change since last notification
01: card present, no change since last notification
10: card removed notification
11: card inserted notification |
| 1-0 |
Status/notification for slot 4 |
00: card absent, no change since last notification
01: card present, no change since last notification
10: card removed notification
11: card inserted notification |