307013-003 Datasheet, PDF (217/848 Pages) Intel Corporation – Intel I/O Controller Hub 7

Functional Description
4. After sending the data packet, the controller waits for a handshake response from
the debug device.
• If a handshake is received, the debug port controller:
— a. Places the received PID in the RECEIVED_PID_STS field
— b. Resets the ERROR_GOOD#_STS bit
— c. Sets the DONE_STS bit
• If no handshake PID is received, the debug port controller:
— a. Sets the EXCEPTION_STS field to 001b
— b. Sets the ERROR_GOOD#_STS bit
— c. Sets the DONE_STS bit
5.20.10.1.2 IN Transactions
An IN transaction receives data from the debug device. It can occur only when the
following are true:
• The debug port is enabled
• The debug software sets the GO_CNT bit
• The WRITE_READ#_CNT bit is reset
The sequence of the transaction is:
1. Software sets the appropriate values in the following bits:
— USB_ADDRESS_CNF
— USB_ENDPOINT_CNF
— TOKEN_PID_CNT[7:0]
— DATA_LEN_CNT
— WRITE_READ#_CNT (note: this will always be 0 for IN transactions)
— GO_CNT (note: this will always be 1 to initiate the transaction)
2. The debug port controller sends a token packet consisting of:
— SYNC
— TOKEN_PID_CNT field
— USB_ADDRESS_CNT field
— USB_ENDPOINT_CNT field
— 5-bit CRC field.
3. After sending the token packet, the debug port controller waits for a response from
the debug device.
If a response is received:
— The received PID is placed into the RECEIVED_PID_STS field
— Any subsequent bytes are placed into the DATA_BUFFER
— The DATA_LEN_CNT field is updated to show the number of bytes that were
received after the PID.
4. If valid packet was received from the device that was one byte in length (indicating
it was a handshake packet), then the debug port controller:
— Resets the ERROR_GOOD#_STS bit
— Sets the DONE_STS bit
Intel ^® ICH7 Family Datasheet
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