C541U_99 Datasheet, PDF (88/192 Pages) Siemens Semiconductor Group – 8-BIT CMOS MICROCONTROLLER

On-Chip Peripheral Components
C541U
CPU Buffer Handling
USB Buffer Handling
CPU page is full : CBF = 1
CPU read access enabled
USB page is empty : UBF = 0
USB write access enabled
CPU reads 1 Byte
SOD = 1
No
CPU buffer
empty?
Yes
CPU buffer is empty : CBF = 0
CPU read access disabled
USB write
No
request?
Yes
USB writes buffer
USB buffer is full: UBF = 1
USB write access disabled
EOD = 1
No
USB page
full?
CPU page
empty?
Yes
Yes
Pages are swapped (CBF = 0 and UBF =1)
Figure 6-26
USB Write Access in Dual Buffer Mode - Buffer Handling
No
MCB03406
Semiconductor Group
6-43
1999-04-01