Read Byte And Read Word Messages With And Without Pec - Texas Instruments TMS320F28004x Technical Reference Manual

Master Mode Operation
23.4.2.5 Read Byte/Word
Figure 23-19. Read Byte and Read Word Messages with and without PEC
S Slave address Wr A
Byte #0 NA P
S Slave address Wr A
Byte #0
S Slave address Wr A
Byte #0
S Slave address Wr A
Byte #0
The Read Byte and Read Word messages consist of a device address, a command byte, received data
bytes from a slave and an optional PEC byte. Read Byte messages include a single byte, while the Read
Word message protocol supports receipt of 2 bytes from the slave. Similar to the Receive Byte Protocol,
the PMBMC register is configured to receive 1 or 2 bytes, the CMD_EN bit is set and the PEC_EN is
configured to expect or not expect a PEC byte appended to the message. The PMBus module will
automatically terminate the message after the expected number of bytes is received from the slave or if
the slave does not properly acknowledge any portion of the message.
In addition to programming the PMBMC register, the firmware is expected to load the command byte into
bits 7-0 of the PMBTXBUF register. Any data received from the slave will be found in the PMBRXBUF
register.
23.4.2.6 Process Call
S Slave address Wr A
Sr Slave address Rd A
S Slave address Wr A
Sr Slave address Rd A
1964
Power Management Bus Module (PMBus)
Command
Command
A PEC NA P
Command
A Byte #1 NA P
Command
A Byte #1 A
Figure 23-20. Process Call Message with and without PEC
Command
Byte #0
Command
Byte #0
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A Sr Slave address Rd A
A Sr Slave address Rd A
A Sr Slave address Rd A
A Sr Slave address Rd A
PEC NA P
A Byte #0
A Byte #1 NA P
A Byte #0
A Byte #1
SPRUI33 – November 4 2015 – Revised January 2017
A Byte #1 A
A Byte #1 A
A PEC NA P
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