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Section 26 USB 2.0 Host/Function Module
Page 1538 of 2108 R01UH0134EJ0400 Rev. 4.00
Sep 24, 2014
SH7262 Group, SH7264 Group
(c) Interval Counting and Transfer Control when the Function Controller Function is
Selected
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 () 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 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 () frame following the () frame in
which the PID bits for the selected pipe has been set to BUF.
Interval counter started
USB bus
PID bit setting
NAK
S
O
F
S
O
F
S
O
F
S
O
F
BUF BUFBUF
D
A
T
A
0
O
U
T
D
A
T
A
0
O
U
T
Token
reception
is waited
Token
reception
is waited
Token
reception
is not waited
Token
reception
is not waited
Toke n
Figure 26.18 Relationship between () 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.