C541U_99 Datasheet, PDF (99/192 Pages) Siemens Semiconductor Group – 8-BIT CMOS MICROCONTROLLER

On-Chip Peripheral Components
C541U
6.4.7 Register Set
Two different kinds of registers are implemented for full speed operation in the USB module. The
global registers (GEPIR, EPSEL, ADROFF, USBVAL) describe the basic functionality of the
complete USB module and can be accessed via unique SFR addresses. For reduction of the
number of SFR addresses which are needed to control the USB module inside the C541U, device
registers and endpoint registers are mapped into an SFR address block of seven SFR addresses
(C1H to C7H). The endpoint specific functionality of the USB module is controlled via the device
registers DCR, DPWDR, DIER, DIRR and the frame number registers. An endpoint register set is
available for each endpoint (n=0..4) and describes the functionality of the selected endpoint. Figure
6-34 explains the structure of the USB module registers.
Global Registers
GEPIR(D6_H)
D 0 0 .4 .3 .2 .1 .0
ADROFF(D4_H)
0 0 .5 .4 .3 .2 .1 .0
USBVAL(D3_H)
.7 .6 .5 .4 .3 .2 .1 .0
EPSEL(D2_H)
.7 0 0 0 0 .2 .1 .0
Decoder
Device
Registers
C1_{H DCR}
C2_{H DPWDR}
C3_{H DIER}
C4_H DIRR
C5_H reserved
C6_{H FNRL}
C7_{H FNRH}
Endpoint 0
Registers
C1_{H EPBC0}
C2_{H EPBS0}
C3_{H EPIE0}
C4_H EPIR0
C5_{H EPBA0}
C6_{H EPLEN0}
C7_H reserved
Endpoint 1
Registers
C1_{H EPBC1}
C2_{H EPBS1}
C3_{H EPIE1}
C4_H EPIR1
C5_{H EPBA1}
C6_{H EPLEN1}
C7_H reserved
Endpoint 2
Registers
C1_{H EPBC2}
C2_{H EPBS2}
C3_{H EPIE2}
C4_H EPIR2
C5_{H EPBA2}
C6_{H EPLEN2}
C7_H reserved
Endpoint 3
Registers
C1_{H EPBC3}
C2_{H EPBS3}
C3_{H EPIE3}
C4_H EPIR3
C5_{H EPBA3}
C6_{H EPLEN3}
C7_H reserved
Endpoint 4
Registers
C1_{H EPBC4}
C2_{H EPBS4}
C3_{H EPIE4}
C4_H EPIR4
C5_{H EPBA4}
C6_{H EPLEN4}
C7_H reserved
Figure 6-34
Register Structure of the USB Module
Note: In the description of the USB module registers bits are marked as “rw“, “r“, or “w“. Bits marked
as “rw“ can be read and written. Bits marked as “r“ can be read only. Writing any value to “r“
bits has no effect. Bits marked as “w“ are used to execute internal commands which are
triggered by writing a 1. Writing a 0 to “w“ bits has no effect. Reading “w“ bits returns a 0.
Semiconductor Group
6-54
1999-04-01