C541U_99 Datasheet, PDF (84/192 Pages) Siemens Semiconductor Group – 8-BIT CMOS MICROCONTROLLER

On-Chip Peripheral Components
C541U
6.4.2.2.2 USB Read Access
Figure 6-22 shows the basic flowchart of a USB read access from one USB memory buffer in single
buffer mode.
SOD = 1
Buffer is empty:
USB read access disabled
CPU write access enabled
Buffer can be written by CPU
Buffer full?
No
Yes
Buffer is full:
USB read access enabled
CPU write access disabled
EOD = 1
USB read request?
No
Yes
Buffer is read by USB
Yes
Buffer empty?
No
MCD03402
Figure 6-22
USB Read Access in Single Buffer Mode - Buffer Handling
Semiconductor Group
6-39
1999-04-01