RM0082
HS_USB 2.0 device
Doc ID 018672 Rev 1
495/844
23.8.7 Device
interrupt
register
The device interrupt is a RW register whose bits are set when there are system-level events.
Indeed interrupts are used by the software application to make system-level decisions. The
device interrupt register bit assignments are given in
[15]
RXFIFO
EMPTY
1'h0
Receive FIFO empty status.
This bit is set as soon as DMA data transfer has been
completed and no new packets have been received. In
contrast, this bit is cleared after receiving a valid packet from
the USB. It is set according to the encoding:
– 1‘b0 = Not empty.
– 1‘b1 = Empty.
[14:13]
ENUM
SPD
2’h0
Enumerated speed.
These 2 bits give the speed at which the subsystem comes
up after the speed enumeration, according to the encoding:
– 2‘b00 = HS.
– 2‘b01 = FS.
– 2‘b10 = LS.
– 2‘b11 = Reserved.
If the expected speed is HS (field SPD = 2‘b00 in the device
configuration register and the udc-ahb Subsystem is
connected to a USB 1.1 host controller, then after speed
enumeration, these bits indicates that the subsystem is
operating in FS mode (2‘b01).
Besides, if SPD states HS again but the UDC-AHB
subsystem is connected to a USB 2.0 host controller, then
after speed enumeration, these bits indicate that the
subsystem is operating in HS mode (2‘b00).
Finally, if the expected speed is either LS (SPD = 2‘b10) or
FS (SPD = 2‘b01) and the UDC-AHB subsystem is connected
to either a USB 1.1 or a USB 2.0 host controller, then after
speed enumeration, these bits indicate that the subsystem is
operating in either LS mode (2‘b10) or FS mode (2‘b01,
respectively).
[12]
SUSP
1'h0
Suspend status.
This bit is set according the encoding:
– 1‘b0 = Not detected.
– 1‘b1 = Detected on USB.
[11:08]
ALT
4’h0
Alternate setting.
Please refer to USB standard for more details.
[07:04]
INTF
4’h0
Interface.
Please refer to USB standard for more details.
[03:00]
CFG
4’h0
Configuration.
Please refer to USB standard for more details.
Table 402.
Device status register bit assignments (continued)
Bit
Name
Reset value Description