Renesas M16C FAMILY, User Manual

Page: 223 / 369

Rev.2.00 Oct 16, 2006 page 212 of 354
REJ09B0340-0200
M30245 Group 2. USB function
(3) Register, Bit
•When the USB reset interrupt request occurs, all the USB internal registers become reset state. To
resume communication, each endpoint needs to be initialized.
•All the USB related registers (16-bit registers) except USB endpoint x(x=0 to 4) IN FIFO data register
(EPxI), USB endpoint x(x=0 to 4) OUT FIFO data register (EPxO), USB control register (USBC), and
USB attach/detach register (USBAD) are available for word access and byte access. The EPxI and
the EpxO are only available for word access or byte access to the lower bytes. The USBC and the
USBAD of 8-bit registers are only available for byte access. After software reset, contents of all the
USB related registers are retained.
•While the USB clock is held disabled in suspend mode, writing in the USB internal registers (other
than USBC, USBAD, and frequency synthesizer-related registers) is disabled.
(4) Packet Data Destruction
•When FLUSH bit of endpoint x OUT control and status register (EPxOCS) is set to “1” during USB
transfer, the receive data may be destroyed. Be sure to set FLUSH bit of the EPxOCS to “1” only
when there are data in OUT FIFO (OUT_BUF_STS1 and OUT_BUF_STS0 are set to “10
2
” or “11
2
”).
•When FLUSH bit of USB endpoint x IN control and status register (EPxICS) is set to “1” during USB
transfer, the transmit data may be destroyed. Be sure to read the IN_BUF_STS1 and the
IN_BUF_STS0 flags and to confirm that there are data in IN FIFO before setting FLUSH bit of the
EPxICS to “1”.
In isochronous transfer, use AUTO_FLUSH bit (bit 0 of address 028C
16
).