Ping Transaction - Epson S2R72V18 Technical Manual

1.4.3.8

PING Transaction

The LSI switches to allow execution of PING transactions under the following conditions for HS
operations with channels performing bulk OUT or control OUT transactions. When the channel is
in PING transaction execution mode, a PING transaction is executed when selected by scheduling.
If an NYET or NAK is received or if no response is received for the OUT transaction, the channel
switches to a mode allowing PING transactions.
If a NAK is received for the PING transaction, the channel continues to enable PING transaction
execution. No status notification is issued to the firmware.
If an ACK is received for the PING transaction, the channel returns from the mode enabling PING
transaction execution to the mode enabling OUT transaction execution. No status notification is
issued to the firmware.
If a STALL is received for the PING transaction, H_CHx{x=0,a-e}Config_0.TranGo is
automatically cleared to end the transfer, and the condition code (H_CHx{x=0,a-e}ConditionCode)
is set to "STALL." A ChangeCondition status notification
(H_CHx{x=0,a-e}IntStat.ChangeCondition bit) is then issued to the firmware.
If a normal response is not received for the PING transaction, the condition code
(H_CHx{x=0,a-e}ConditionCode) is set to "RetryError." A TranErr status notification
(H_CHx{x=0,a-e}IntStat.TranErr bit) is issued to the firmware. Retry processing is performed here,
but if three successive errors occur, H_CHx{x=0,a-e}Control.TranGo is automatically cleared to
end the transfer, and a ChangeCondition status notification
(H_CHx{x=0,a-e}IntStat.ChangeCondition bit) is issued to the firmware.
The FIFO is not updated for PING transactions.
Fig. 1-30 shows the configuration for an ACK response to a PING transaction. (a) The LSI issues a
PING token addressed to the OUT-direction endpoint existing in the node. (b) The device returns an
ACK response to the PING transaction if there is space equivalent to the maximum packet size at
the endpoint.
S2R72V18 Technical Manual (Rev.1.00)
EPSON
1. Functions
67