C541U_99 Datasheet, PDF (109/192 Pages) Siemens Semiconductor Group – 8-BIT CMOS MICROCONTROLLER

On-Chip Peripheral Components
C541U
The device interrupt request register DIRR contains the interrupt request flags of the different types
of device interrupts. All Interrupt request flags in DIRR are reset by hardware after DIRR has been
read.
USB Device Interrupt Request Register DIRR (Address C4H)
Bit No. MSB
7
6
5
4
3
2
C4H SE0I DAI
DDI
SBI
SEI
STI
r
r
r
r
r
r
Reset Value : 00H
LSB
1
0
SUI SOFI DIRR
r
r
Bit
SE0I
DAI
DDI
SBI
SEI
STI
SUI
SOFI
Function
Single ended zero interrupt
Bit SE0I is set each time a single ended zero is detected for equal or greater than
2.5µs. EOP (2 bit times) is not detected.
Device attached interrupt
Bit DAI is automatically set after detection of the USB device being attached to the
USB bus.
Device detached interrupt
Bit DDI is automatically set after detection of the device being detached from the
USB bus.
Suspend begin interrupt
Bit SBI is automatically set when the suspend mode is entered.
Suspend end interrupt
Bit SEI is automatically set when the suspend mode is left.
Status interrupt
Bit STI is set if the host requests a status transfer and the device answers with
NACK (if bit ESP is set, the device answers with ACK and STI is not set).
Setup interrupt
Bit SUI is automatically set after a successful reception of a setup packet which is
not handled by the USB module and must be forwarded to the CPU. The setup
packet itself is limited to 8 bytes and is stored at USB memory adresses 00H to
07H and can be accessed with EPSEL.7=1.
If a setup interrupt occurs (STI is set), the control and status bits UBF0, CBF0,
SOD0, and DIR0 in the endpoint 0 registers EPBS0 and EPIR0 are cleared.
DIR0=0 predicts the direction of the next USB access (data phase) to be from host
to CPU. Bit DIR0 is automatically set (CPU to host), if the host tries to perform a
read access in the first data packet.
Start of frame
Bit SOF is automatically set after detection of a start of frame packet on the USB.
Semiconductor Group
6-64
1999-04-01