28 USB FUNCTION CONTROLLER (USB)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
28-11
(F9) Although data packet transmission in the IN transaction has been completed, the FIFO region is not
freed since the transaction is not closed. Since the FIFO has some available space, Port transfer con-
tinues.
(F10) The FIFO region is freed when the transaction is closed upon reception of an ACK handshake packet.
Although Port transfer pauses as all the available space has been consumed, it is resumed upon clos-
ing of the IN transaction that creates available space.
Auto-negotiation function
This function automatically performs Suspend detection, Reset detection and Resume detection, checking the
state of the USB bus for each operation. You can check each interruption (DetectReset and DetectSuspend) to
confirm what has been actually performed.
DISABLE
EnAutoNego != 1
irq_DetectSuspend
InSUSPEND != 0
irq_DetectReset
irq_NonJ == 1
NORMAL state
RESET state
SUSPEND state
RESUME state
NORMAL
irq_DetectReset == 0
and
irq_DetectSuspend == 0
EnAutoNego == 0
InSUSPEND == 0
EnAutoNego == 1
EnDetectReset = 1
EnDetectSuspend = 1
DisBusDetect = 0
DetectSeq = start
DetectSeq = stop
DetectSeq = start
DetectSeq = stop
set_InSUSPEND = 1
IN_SUSPEND
LineState == K
WAIT_SE0
WAIT_SE0END
LineState == SE0
LineState == J
LineState == SE0
LineState == SE0
LineState == K
evt_DetectReset
CHK_EVENT
5.1.8 Auto-negotiator
Figure 28.