C541U_99 Datasheet, PDF (123/192 Pages) Siemens Semiconductor Group – 8-BIT CMOS MICROCONTROLLER

On-Chip Peripheral Components
C541U
6.4.8.5 Register Set
A set of control and data registers are defined for the USB module in low speed operation.
USB Module Control Register USBDCR (Address E7H)
Reset Value : 00H
Bit No. MSB
LSB
7
6
5
4
3
2
1
0
E7H TYPE3 TYPE2 TYPE1 TYPE0 LEN3 LEN2 LEN1 LEN0 USBDCR
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Bit
TYPE3 - 0
Function
Transfer Type
TYPE3 - 0 Description
0000
Empty
Software is required to write this value to generate an
acknowledgement and trigger the next activity in the
hardware.
0001
Reserved
0010
0011
0100
SETUP packet
A SETUP packet has been received and the setup data is
stored in the USBDRn registers and SETUP interrupt request
is also generated. A read operation to register USBDCR
resets the pending interrupt request, while TYPE bit field
maintains its current value (0010_B).
OUT packet
An OUT packet has been received by endpoint zero and is
stored in the USBDRn registers and OUT interupt request is
generated. A read operation to register USBDCR resets the
pending interrupt request, while TYPE bit field maintains its
current value (0011_B).
Stall
The module is stalled including control endpoint and both
interrupt endpoints.
0101
IN packet
An IN packet has been set up for endpoint zero, which is
directed to the host. Software is required to write this value to
trigger the data packet to be sent to the host.
Semiconductor Group
6-78
1999-04-01