NEC Network Controller uPD98502 - Manual (Page 356)

CHAPTER 6 USB CONTROLLER
356 Preliminary User’s Manual S15543EJ1V0UM
6.6.6.3 Separate mode
The following figure illustrates the receive operations performed by USB Controller in Separate Mode.
Figure 6-23. USB Controller Receive Operation Sequence (Separate Mode)
S tores the data from U S B to
receive F IF O
R eceives data
from U SB
- C R C ve rify
- Bit S tuffing verify
- N R Z I de code
B uffer is remaining
in system memory
area ?
Y es
N o
D M A transfers to
system memory
W rites R x indicatio n
U pdates write poin ter,
S ets R x completio n bit of
correspon ding End Point in
U G SR register
(1)
(2)
(4)
(8)
(10)
(11)
(3)
W aits data
F etches new
buffer descriptor
E ncounte rs link po inter ?
U pdates P ool Information
R egisters
N o
Y es
D ata S ize < M axP ?
(9)
N o
(5)
(6)
(7)
B uffer be comes full ?
(12) Y es
Y es
N o