SH7764 Datasheet, PDF (1048/1752 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC Engine Family SH-4A Series

Section 21 USB 2.0 Host/Function Module (USB)
(c) Interval Counting and Transfer Control when the Function Controller Function is
Selected
(i) When the selected pipe is for isochronous OUT transfers
This module generates the NRDY interrupt when this module fails to receive a data packet within
the interval set by the IITV bits in terms of (µ) frames.
This module generates the NRDY interrupt when this module fails to receive a data packet
because of a CRC error or other errors contained in the packet, or because of the FIFO buffer
being full.
This module generates the NRDY interrupt on receiving an SOF packet. Even if the SOF packet is
corrupted, the internal interpolation is used and allows the interrupt to be generated at the timing
to receive the SOF packet.
However, when the IITV bits are set to the value other than 0, this module generates the NRDY
interrupt on receiving an SOF packet for every interval after starting interval counting operation.
When the PID bits are set to NAK by software after starting the interval timer, this module does
not generate the NRDY interrupt on receiving an SOF packet.
The interval counting starts at the different timing depending on the IITV bit setting as follows.
 When IITV = 0: The interval counting starts at the (µ) frame following the (µ) frame in
which software has set the PID bits for the selected pipe to BUF.
S
S
SOD SOD
O
O
OU A OU A
(µ) frame
F
F
FTT
A
FTT
A
0
0
PID bit setting
Token
NAK
BUF
BUF
BUF
Token
Token
Token
reception reception reception
is not waited is not waited is waited
Token
reception
is waited
Interval counter started
Figure 21.14 Relationship between (µ) Frames and Expected Token Reception when IITV =
0
 When IITV ≠ 0: The interval counting starts on completion of successful reception of the
first data packet after the PID bits for the selected pipe have been modified to BUF.
Rev. 1.00 Nov. 22, 2007 Page 992 of 1692
REJ09B0360-0100