Filter
Top Products
Section 26 USB 2.0 Host/Function Module
R01UH0134EJ0400 Rev. 4.00 Page 1505 of 2108
Sep 24, 2014
SH7262 Group, SH7264 Group
(6) Response PID
The PID bits in DCPCTR and PIPEnCTR are used to set the response PID for each pipe.
The following shows this module operation with various response PID settings:
(a) Response PID settings when the host controller function is selected
The response PID is used to specify the execution of transactions.
NAK setting: Using pipes is disabled. No transaction is executed.
BUF setting: Transactions are executed based on the status of the buffer memory. For OUT
direction: If there are transmit data in the buffer memory, an OUT token is issued.
For IN direction: If there is an area to receive data in the buffer memory, an IN token is issued.
STALL setting: Using pipes is disabled. No transaction is executed.
Setup transactions for the DCP are set with the SUREQ bit.
(b) Response PID settings when the function controller function is selected
The response PID is used to specify the response to transactions from the host.
NAK setting: The NAK response is always returned in response to the generated transaction.
BUF setting: Responses are made to transactions based on the status of the buffer memory.
STALL setting: The STALL response is always returned in response to the generated
transaction.
For setup transactions, an ACK response is always returned, regardless of the PID setting, and the
USB request is stored in the register.
This module may carry out writing to the PID bits, depending on the results of the transaction.
(a) When the host controller function has been selected and the response PID is set by
hardware
NAK setting: In the following cases, PID = NAK is set and issuing of tokens is automatically
stopped:
When, during a transfer other than isochronous transfer, three receive errors such as no
response, bit stuffing error, or CRC error are returned in succession after token
transmission.
When, during isochronous transfer, three receive errors such bit stuffing error or CRC error
are returned in succession after token transmission.