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Section 26 USB 2.0 Host/Function Module
R01UH0134EJ0400 Rev. 4.00 Page 1545 of 2108
Sep 24, 2014
SH7262 Group, SH7264 Group
(2) Transfer Schedule
This section describes the transfer scheduling within a frame of this module. After the module
sends an SOF, the transfer is carried out in the sequence described below.
1. Execution of periodic transfers
A pipe is searched in the order of Pipe 1 Pipe 2 Pipe 6 Pipe 7 Pipe 8 Pipe 9, and
then, if the pipe is one for which an isochronous or interrupt transfer transaction can be
generated, the transaction is generated.
2. Setup transactions for control transfers
The DCP is checked, and if a setup transaction is possible, it is sent.
3. Execution of bulk and control transfer data stages and status stages
A pipe is searched in the order of DCP Pipe 1 Pipe 2 Pipe 3 Pipe 4 Pipe 5, and
then, if the pipe is one for which a bulk or control transfer data stage or a control transfer status
stage transaction can be generated, the transaction is generated.
If a transfer is generated, processing moves to the next pipe transaction regardless of whether
the response from the peripheral device is ACK or NAK. Also, if there is time for the transfer
to be done within the frame, step 3 is repeated.
(3) USB Communication Enabled
Setting the UACT bit of the DVSTCTR register to 1 initiates sending of an SOF or SOF, and
makes it possible to generate a transaction.
Setting the UACT bit to 0 stops the sending of the SOF or SOF and initiates a suspend state. If
the setting of the UACT bit is changed from 1 to 0, processing stops after the next SOF or SOF is
sent.