USB PD SOP*?

걍 패킷을 보낸다 라는걸 죄다 SOP라고 퉁치는것 같은데

SOP

SOP'

SOP''

SOP* 이런게 나와서 헷갈리는 중..

 

SOP* • Start of packet (SOP/SOP’/SOP’’)

[링크 : https://usb.org/sites/default/files/D2T2-1%20-%20USB%20Power%20Delivery.pdf]

 

SOP* - The Start of Frame field in a USB Power Delivery packet indicates the intended recipient of the packet.

[링크 : https://ww1.microchip.com/downloads/en/AppNotes/00001974A.pdf]

 

50h 에 TRANSMIT 이라는 레지스터가 있는데 Read / Write 이고 [2:0] 3비트는 아래의 값을 지닌댄다.

도대체 cable reset은 왜 저기서 튀어나오는걸까?

[링크 : https://www.nxp.com/docs/en/data-sheet/PTN5110.pdf]

 

각 패킷별 전송이나 응답할 녀석이 달라지는건가?

[링크 : https://www.graniteriverlabs.com/en-us/technical-blog/usb-pd-power-delivery-spec-versions]

 

 

5 Sending a USB PD message The general steps of transmitting a SOP* message are listed below. Please consult sections 4.7.1, 4.7.2, and 4.7.3 of the TCPC specification[3] for more detailed implementation and examples. • Step 0: TCPM writes the content of the message to be transmitted into the TRANSMIT_BUFFER • Step 1: TCPM writes to TRANSMIT requesting SOP* transmission • Step 2: The outcome reported by the TCPC may be one of three indications after asserting the Alert# pin: – If the TCPC PHY layer successfully transmits the message, the TCPC sets the Transmission Successful bit in the ALERT register. – If the TCPC PHY layer did not get any response after retries, the TCPC sets the Transmission Failed bit in the ALERT register. – If the transmission was discarded due to an incoming message, the TCPC sets the Transmission Discarded bit in the ALERT register. • Step 3: Before requesting another transmission, the TCPM shall clear the alert by writing a 1 to the asserted bit in the ALERT register. When transitioning through the steps of transmitting SOP* message, TCPC may assert ALERT.ReceiveStatus or ALERT.ReceivedHardReset bit at any time to notify that a message was received.

[링크 : https://www.nxp.com/docs/en/application-note/AN12137.pdf]

 

위에서 4.7.1~4.7.3을 보라는데 제목만 봐서는.. 흐음..

4.7 USB PD Communication Operational Model 4.7.1 Transmitting an SOP* USB PD Message with Less than or Equal to 128 Data Bytes 4.7.2 Transmitting an SOP* USB PD Message with Greater than 128 Data Bytes 4.7.3 Transmitting a Hard Reset Message

[링크 : https://www.usb.org/sites/default/files/documents/usb-port_controller_specification_rev2.0_v1.0_0.pdf]

 

RDO (Request Data Object)

[링크 : https://www.ti.com/lit/an/slva842/slva842.pdf]