Intel C2518 FH8065501516710 Data Sheet

Intel

®

 Atom™ Processor C2000 Product Family for Microserver

Datasheet, Vol. 2 of 3

September 2014

280

Order Number: 330061-002US

An IN transaction receives data from the debug device and occurs 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. The 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 is always 0 for IN transactions.)
GO_CNT (Note: This is always 1 to initiate the transaction.)

2. The debug port controller sends a token packet consisting of the following:

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:
a. The received PID is placed into the RECEIVED_PID_STS field.
b. Any subsequent bytes are placed into the DATA_BUFFER.
c. The DATA_LEN_CNT field is updated to show the number of bytes that were 

received after the PID.

4. If the valid packet was received from the device that was one byte in length 

(indicating it was a handshake packet), then the debug port controller:
a. Resets the ERROR_GOOD#_STS bit.
b. Sets the DONE_STS bit.

5. If valid packet was received from the device that was more than one byte in length 

(indicating it was a data packet), then the debug port controller:
a. Transmits an ACK handshake packet.
b. Resets the ERROR_GOOD#_STS bit.
c. Sets the DONE_STS bit.

6. If no valid packet is received, then 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.