C541U_99 Datasheet, PDF (119/192 Pages) Siemens Semiconductor Group – 8-BIT CMOS MICROCONTROLLER

On-Chip Peripheral Components
C541U
The endpoint base address register defines the location and size (start address and length) of the
endpoint specific buffers in the USB memory. See also figure 6-31 for an example of EPBAn and
EPLENn register setup.
Endpoint n Base Address Register EPBAn, n=0-4 (Address C5H)
Reset Value : 00H
Endpoint n Buffer Length Register EPLENn, n=0-4 (Address C6H) Reset Val.: 0XXXXXXXB
Bit No. MSB
LSB
7
6
5
4
3
2
1
0
C5H PAGEn 0
0
0
An6 An5 An4 An3 EPBAn
r
r
r
r
rw
rw
rw
rw
C6H
0
r
Ln6 Ln5 Ln4 Ln3 Ln2 Ln1 Ln0 EPLENn
rw
rw
rw
rw
rw
rw
rw
Bit
PAGEn
An6-An3
Ln6-Ln0
0
Function
Buffer page for endpoint n (single buffer mode only)
In single buffer mode, the endpoint n can be either located on USB memory buffer
page 0 (PAGEn=0) or on USB memory buffer page 1 (PAGEn=1) by clearing or
setting this bit. In dual buffer mode this bit has no effect.
Note: The SETUP token is always stored on USB memory buffer page 0 at
address 00H to 07H_.
Endpoint n buffer start address
The bits 0 to 3 of EPBAn are the address bits A6 to A3 of the USB memory buffer
start address for endpoint n. A7 and A2-A0 of the resulting USB memory buffer
start address are set to 0.
Endpoint n buffer length
The bits 0 to 6 if EPLENn define the length of the USB memory buffer for endpoint
n and cannot be written if DINIT=1.
Reserved for future use. For compatiblity, these bits have to be ignored in all read
accesses and written with zero in all write accesses.
The USB buffer allocation and organization is described in detail in section 6.4.3.
Semiconductor Group
6-74
1999-04-01