NEC Network Controller uPD98502 - Manual (Page 338)

CHAPTER 6 USB CONTROLLER
338 Preliminary User’s Manual S15543EJ1V0UM
6.5.4 V R 4120A processing at data transmitting
This section explains the processing performed by the V R 4120A when transmitting data.
Figure 6-7. V
R
4120A Processing at Data Transmitting
Prep are T x data
in th e memory
R e ads U SB T x EndP oint
Status R e giste r
R e ads U SB C o mmand R egister
Bu sy b it = "1 " ?
En dPoin t is B usy ?
Ye s
Ye s
N o
N o
Issues transmit
comm and
R e ads U SB G e neral Status R eg iste r
R e ads register (T M R A) which ad dresses
tra nsmit ma ilb ox
R e ads T x indication
U p dates read p ointer o f mailbox
Issue proce ssing of T x
comm and
R e ad proce ssing of T x
indica tion
(1)
(2)
(4)
(5)
(6)
(9)
(7)
(10)
(11)
(3)
En d o f transmission ?
Ye s
N o
U S B C on tro ller
tra nsmits the da ta
to U SB .
(8)