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Section 26 USB 2.0 Host/Function Module
Page 1530 of 2108 R01UH0134EJ0400 Rev. 4.00
Sep 24, 2014
SH7262 Group, SH7264 Group
26.4.7 Interrupt Transfers (PIPE6 to PIPE9)
When the function controller function is selected, 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.
When the host controller function is selected, this module can set the timing of issuing a token
using the interval timer. At this time, this module issues an OUT token even in the OUT direction,
without issuing a PING token.
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.
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.