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Section 26 USB 2.0 Host/Function Module
Page 1536 of 2108 R01UH0134EJ0400 Rev. 4.00
Sep 24, 2014
SH7262 Group, SH7264 Group
The interval counter is not initialized under the conditions noted below.
1. When the PID bit is set to NAK or STALL
The interval timer does not stop. This module attempts the transactions at the subsequent
interval.
2. The USB bus reset or the USB is suspended
The IITV bit is not initialized. When the SOF has been received, the counter is restarted from
the value prior to the reception of the SOF.
(b) Interval Counting and Transfer Control when the Host Controller Function is Selected
This module controls the interval between token issuance operations based on the IITV bit
settings. Specifically, this module issues a token for a selected pipe once every 2
IITV
() frames.
This module counts the interval every 1-ms frame for the pipes used for communications with the
full-speed or low-speed peripheral devices connected to a high-speed HUB.
This module starts counting the token issuance interval at the () frame following the () frame in
which the PID bits have been set to BUF.
Interval counter started
USB bus
PID bit setting
Token
issued
Toke n
Token
issued
Token
not issued
Token
not issued
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
Figure 26.16 Token Issuance when IITV = 0