Usb Module - Siemens C541U User Manual

6.4

USB Module

The USB module in the C541U handles all transactions between the serial USB bus and the internal
(parallel) bus of the microcontroller. The USB module includes several units which are required to
support data handling with the USB bus : the on-chip USB bus transceiver, the USB memory with
two pages of 128 bytes each, the memory management unit (MMU) for USB and CPU memory
access control, the UDC device core for USB protocol handling, the microcontroller interface with
the USB specific special function registers and the interrupt control logic. A clock generation unit
provides the clock signal for the USB module for full speed and low speed USB operation. The
following sections describe the full speed operation, while the low speed operation is described
specifically in section 6.4.8. Figure 6-18 shows the block diagram of the functional units of the USB
module with their interfaces.
XTAL1 XTAL2
Pin Pin
Osc.
12 MHz
x 4
2
PLL
6 MHz
48 MHz
Figure 6-18
USB Module Block Diagram
Semiconductor Group
USB Bus
D+ D-
Pin Pin
7
F
H
Transceiver
(On-chip)
00
H
Data
USB
Device
Core
(UDC)
Control
Interrupt Generation
6-34
On-Chip Peripheral Components
7
F
H
Page 1
Page 0
USB
Memory
00
H
(128 x 8)
Data
Address
MMU
USB Memory
Management Control
C541U
USB
Module
Internal
Bus
MCU
Interface
11
SFR
Addr.
MCB03380
1999-04-01