Communication Operation; Initialization; Figure 15.3 Usb Initialization - Hitachi H8S/2215 Series Hardware Manual

15.5

Communication Operation

15.5.1

Initialization

The USB must be initialized as described in the flowchart in figure 15.3.
USB function
Cancel power-on reset
Start USB operationg clock
USB operating clock
stabilization time has
USB operating clock
stabilization detection
interrupt occurs.
USB interface operation OK
Set each interrupt
Note:
*
Rev. 3.0, 10/02, page 484 of 686
oscillation.
No
passed?
Yes
Set EPINFO
Before entering the software standby state, USB module operation must be stopped by setting the
MSTPB0 bit of MSTPCRB register to 1.

Figure 15.3 USB Initialization

Firmware
Select USB operating clock
(Write UCKS0 to UCKS3
Cancel USB module stop
mode (Clear MSTPB0 in
Wait for USB operating
Cancel USB interface reset
(Clear UIFRST of UCTLR
Clear CK48READY in UIFR3
Write 115-byte data to
UEPIR00_0 to UEPIR22_4)
(Bus powered)
No
Stop USB module operation
(Write MSTPB0 in MSTPCRB to 1)
Enter software standby state
To USB cable
connecting procedure
15.5.2 to (1)
in UCTLR)
MSTPCRB to 0)
clock stabilization
to 0
to 0
Set EPINFO
Set each interrupt
Self powered?
Yes
(Self powered)
System
enters power-down
No
mode?
Yes
*
*
(If necessary)
Wait for USB cable
connection