FUSB307BMPX datasheet(10/57 Pages) ONSEMI

10 / 57 page

FUSB307B

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BMC Power Delivery

The Type−C connector allows USB Power Delivery (PD)

to be communicated over the connected CC pin between two

ports. The communication method is the BMC Power

Delivery protocol and is used for many different reasons

with the Type−C connector. Possible uses are outlined

below.

• Negotiating and controlling charging power levels

• Alternative Interfaces such as MHL, Display Port

• Vendor specific interfaces for use with custom docks or

accessories

• Role swap for dual−role ports that want to switch who

is the host or device

• Communication with USB3.1 full featured cables

The FUSB307B integrates a thin BMC PD client which

includes the BMC physical layer and packet buffers which

allows packets to be sent and received by the host software

through I2C accesses.

Receive State Machine

The TCPM can setup the desired types of messages to be

received by the FUSB307B via the RXDETECT register.

This register defaults to 0x00 (Receiver disabled) upon

power up, reset, Hard Reset transmission and reception, and

upon detecting a cable disconnect. A message is not received

unless it is first enabled. Figure 9 shows the FUSB307B

receive state machine.

Upon a successfully transmitting GoodCRC, the

RXSTAT register is updated with the type of message

received and the TCPM is alerted via ALERTL.I_RXSTAT

bit (see transition from PRL_Rx_Send_GoodCRC to

PRL_Rx_Report_SOP* in Figure 9). The total number of

bytes in the receive buffer RXDATA is stored in

RXBYTECNT This number includes the header bytes that

are stored in RXHEADL and RXHEADH and the RXSTAT

The RXBYTECNT, RXSTAT registers and the internal

receive buffer will be cleared after the ALERTL.I_RXSTAT

bit is cleared.

The FUSB307B will automatically transmit a GoodCRC

message for valid enabled messages within tTransmit.

A received message is valid when:

• It is not a GoodCRC message

• The calculated CRC is correct

• The SOP* type is enabled

The makeup of the GoodCRC message is formed by the

received SOP* type and the contents of MSGHEADR

When an expected GoodCRC message or a Hard Reset

signaling is received, they will not be replied with a

GoodCRC message (see Note 2 in Figure 9). If a GoodCRC

message received was not expected due to the SOP* type or

mismatched Message ID, the receive state machine will not

send a GoodCRC message and will transition to

PRL_Rx_Report SOP* to inform the TCPM.

If a Hard Reset message is received, the FUSB307B will

reset the RXDETECT preventing the reception of future

messages until the TCPM re−enables it.

Figure 9. Receive State Machine

Message received from PHY

GoodCRC Transmission complete

Start

PRL_Rx_Send_GoodCRC

Actions on entry:

Send GoodCRC message to PHY

PRL_Rx_Wait_for_PHY_

message

Actions on entry:

PRL_Rx_Report_SOP*

Actions on entry:

Update RECEIVE_STATUS

(ALERT_L.RXSTAT asserted)

Message discarded

bus Idle

PRL_Rx_Message_Discard

Actions on entry:

If Tx State−Machine active, discard

transmission and assert

ALERT_L.TXDISC

else

Unexpected

GoodCRC received

FUSB305 receives Hard reset |

Cable reset

1. This indication is sent by the PHY when a message has been discarded due to CC being busy, and after CC becomes idle again

(see USB PD Spec).

2. Messages do not include Hard Reset or Cable Reset signals or expected GoodCRC messages (GoodCRC messages are only

expected after the FUSB305 PHY has received the tx message and the FUSB305 Tx state−machine is in the

PRL_Tx_Wait_for_PHY_response state).

(Note 1)

(Note 2)

FUSB307BMPX Datasheet(PDF) 10 Page - ON Semiconductor

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