S
Alert Response Addr
Rd
A
Device Addr
NA
P
S
Device Addr
Wr
A
Command
A
Byte Count = N
A
Byte #0
A
……
Byte #(N-1)
A
Sr
Device Addr
Rd
A
Byte Count = N
A
Byte #0
A
……
Byte #(N-1)
A
PEC
NA
P
S
Device Addr
Wr
A
Command
A
Byte Count = N
A
Byte #0
A
……
Byte #(N-1)
A
Sr
Device Addr
Rd
A
Byte Count = N
A
Byte #0
A
……
Byte #(N-1)
NA
P
Master Mode Operation Reference
379
SNIU028A – February 2016 – Revised April 2016
Copyright © 2016, Texas Instruments Incorporated
PMBus Interface/I2C Interface
10.7.9 Block Write-Block Read Process Call
Figure 10-41. Block Write-Block Read Process Call w/o PEC Byte
Figure 10-42. Block Write-Block Read Process Call with PEC Byte
The Block Read-Block Write Process Call protocol combines the Block Write and Block Read protocols,
removing the stop condition between the two messages. The operation of the Master is similar to a Block
Write operation. Loading the block length into the byte count bits of the Master Control Register provides
the length of the Block Write portion of the message. In addition, the PRC_CALL bit within the Master
Control Register must be enabled. Upon completion of the Block Write part of the message, the PMBus
Interface will automatically issue a Repeated Start condition on the PMBus and start transmission of the
Block Read portion of the message. Operation of the PMBus Interface after the Repeated Start condition
is the same as would be in a simple Block Read Message.
10.7.10 Alert Response
Figure 10-43. Alert Response
The Alert Response Message is utilized when the Master detects an alert condition from a Slave on the
PMBus. In Master mode, the Alert Response Message is simply a Receive Byte message with PEC
disable and the Slave Address set to 0xC (Alert Response Address). The PMBus Interface detects the
Alert condition on an input and interrupts the firmware indicating the assertion of an alert condition (Slave
desires to communicate with Master). Programming the Master Control Register with the Alert Response
Address, initiates the Alert Response message and provides the device address of the Slave requesting
service. The device address will be found in the Receive Data Register following receipt of the EOM
interrupt.