H8SSLASH2218 datasheet(549/750 Pages) RENESAS

549 / 750 page

Section 14 Universal Serial Bus (USB)

Rev.6.00 Jun. 03, 2008 Page 501 of 698

REJ09B0074-0600

(4) USB Cable Disconnection (When USB module stop or power-down mode is used)

If the USB cable enters the disconnection state from the connection state in an application (self

powered) where USB module stop or power-down mode is used, perform the operation as

shown in figure 14.6.

Disconnect the USB cable

USB function

Firmware

Yes

Enable D+ pull-up

by port 36 (P36)

Enter power-down mode

(only if necessary)

Wait for USB

cable connection

Yes

Stop USB module

Write MSTPB0 in MSTPCRB to 1

Reset UDC core

Write UDCRST in UCTRL to 1

Reset UDC core

System needs to

enter power-down

mode?

EXIRQx

External interrupt

IRQx*1

Notes:

VBUS interrupts in the USB module cannot be detected in power-down mode or in the USB

module stop state. Accordingly, in an application (self powered) where power-down mode or

USB module stop is used , VBUS interrupts of the USB must bedetected via the external

interrupt pin

IRQx. In this case, the IRQx pin must be specified as both edge sensitive.

When

IRQx is used, VBUS interrupts in the USB module need not to be used.

Before entering power-down mode, make sure to set USB module stop2 (the MSTPB0 bit of

MSTPCRB = 1).

Check the USB cable

disconnection state

Start USB operating

clock oscillation

USB operating

clock stabilization time

has passed?

USB operating clock

stabilization detection

interrupt occurs.

Powe-down mode ?

USB module

stopped?

Cancel USB module stop 2

Clear MSTPB0 in MSTPCRB to 0

Wait for USB operating clock

stabilization

Check connections by using

the port function of

IRQx

Clear CK48READY in UIFR3 to 0

Figure 14.6 USB Cable Disconnection

(When USB Module Stop or Power-Down Mode Is Used)

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