C541U_99 Datasheet, PDF (100/192 Pages) Siemens Semiconductor Group – 8-BIT CMOS MICROCONTROLLER

On-Chip Peripheral Components
C541U
6.4.7.1 Global Registers
The global registers GEPIR, EPSEL, ADROFF, and USBVAL describe the global functionality of the
USB module and can be accessed via unique SFR addresses.
The Endpoint Select Register EPSEL contains 4 bits which are used to select one of the register
blocks of the five endpoint register blocks or the device register block. These register blocks are
mapped to the same SFR address range of C1H to C7H.
USB Endpoint Select Register EPSEL (Address D2H)
Reset Value : 80H
Bit No. MSB
LSB
7
6
5
4
3
2
1
0
D2H EPS7
0
0
0
0
EPS2 EPS1 EPS0 EPSEL
rw
r
r
r
r
rw
rw
rw
Bit
EPS7
EPS2
EPS1
EPS0
Function
Endpoint / device register block select bits
These four bits select the active register block of endpoint or device registers.
EPS7
1
0
0
0
0
0
0
0
EPS2
X
0
0
0
0
1
1
1
EPS1
X
0
0
1
1
0
0
1
EPS0
X
0
1
0
1
0
1
X
Selected Register
Device register set selected
Endpoint 0 register set selected
Endpoint 1 register set selected
Endpoint 2 register set selected
Endpoint 3 register set selected
Endpoint 4 register set selected
reserved
reserved
Table 6-7 shows the register definitions of each endpoint or device register block
in detail.
Semiconductor Group
6-55
1999-04-01