h8s-2172 Renesas Electronics Corporation., h8s-2172 Datasheet - Page 395

• Manufacturer Part Number: h8s-2172
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family H8s-2100 Series
• Manufacturer: Renesas Electronics Corporation.

4. Clearing Suspend Signal Output Mask
5. Entering Software Standby Mode
6. Recover Event from Suspend
7. Suspend Recover Interrupt (SUSRI)
8. USB Suspend Interrupt (USBI2)
To prevent access to the USB module by the CPU or DMAC from occurring in the interrupt
processing routine, the USUSOUT bit in USBSUSP is set to 1 after the setting such as to stop
the DMAC is made. Then output of the USSUSP pin goes low and the USCLK input from the
external transceiver is stopped.
After the USCLK input is stopped, do not access the USB module registers by the CPU or
DMAC.
When the USB bus state enters the state other than the USB idle state before software standby
mode is entered, the suspend recover interrupt (SUSRI) is set in order to clear software standby
mode.
To enable the suspend recover interrupt (SUSRI), clear the SUSRIF bit in PFCR3 to 0 and then
set the SUSRIE bit in PFCR3 to 1.
After that, the SLEEP instruction is executed while the SSBY bit in SBYCR is set to 1 in order
to enter software standby mode.
The system clock (φ) is stopped and this LSI enters the power-down state.
If the USB bus state recovers from the suspend state, the suspend recover interrupt (SUSRI) is
requested. By this interrupt request, software standby mode can be cancelled.
If the USB bus state recovers from the suspend state, the USSUSP pin is negated and this LSI
starts oscillation. After the specified oscillation stabilization time is elapsed, the internal
system clock is supplied and the CPU executes the suspend recover interrupt (SUSRI)
processing.
In the interrupt processing routine, clear the SUSRIF bit in PFCR3 to 0 and then clear the
SUSRIE bit in PFCR3 to 0 in order to disable the suspend recover interrupt (SUSRI).
At this time, the USBI2 interrupt is requested. The priority of the SUSRI interrupt must be
higher than that of the USBI2 interrupt.
After recovering from the SUSRI interrupt processing, the pending USBI2 interrupt processing
is executed.
To mask output of the USSUSP pin (fix to 1), clear the USUSOUT bit in USBSUSP to 0 in the
interrupt processing routine.
Then access to the USB registers can be performed by the CPU or DMAC.
Rev. 2.00, 03/04, page 363 of 534