SH7203 Datasheet, PDF (1240/1686 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7200 Series

Section 23 USB 2.0 Host/Function Module (USB)
23.4.7 Interrupt Transfers (PIPE6 and PIPE7)
This module carries out interrupt transfers in accordance with the timing controlled by the host
controller. For interrupt transfers, PING packets are ignored (no responses are sent), and the ACK,
NAK, and STALL responses are carried out without an NYET handshake response being made.
This module does not support high bandwidth transfers of interrupt transfers.
(1) Interval Counter during Interrupt Transfers when the Host Controller Function is
Selected
For interrupt transfers, intervals between transactions are set in the IITV bits in PIPEPERI. This
controller issues an interrupt transfer token based on the specified intervals.
(a) Counter Initialization
This controller initializes the interval counter under the following conditions.
• Power-on reset:
The IITV bits are initialized.
• Software reset:
The IITV bits are initialized.
• Buffer memory initialization using the ACLRM bit:
The IITV bits are not initialized but the count value is. Setting the ACLRM bit to 0 starts
counting from the value set in the IITV bits.
Note that the interval counter is not initialized in the following case.
• USB bus reset, USB suspended:
The IITV bits are not initialized. Setting 1 to the UACT bit starts counting from the value
before entering the USB bus reset state or USB suspended state.
(b) Operation when Transmission/Reception is Impossible at Token Issuance Timing
This module cannot issue tokens even at token issuance timing in the following cases. In such a
case, this module attempts transactions at the subsequent interval.
• When the PID is set to NAK or STALL.
• When the buffer memory is full at the token sending timing in the receiving (IN) direction.
• When there is no data to be sent in the buffer memory at the token sending timing in the
sending (OUT) direction.
Rev. 2.00 Apr. 16, 2008 Page 1210 of 1652
REJ09B0313-0200