Memory Write Functionality
443
SNIU028A – February 2016 – Revised April 2016
Copyright © 2016, Texas Instruments Incorporated
Boot ROM and Boot Flash
The ROM version for the other members of the UCD3138 family is shown in
.
Table 13-1. ROM Version for the Other Members of the UCD3138 Family
Device
ROM Version
UCD3138, UCD3138A
0x00030002
UCD3138064, UCD3138064A
0x00040001
UCD3138A64, UCD3138A64A
0x00060001
UCD3138128, UCD3138128A
0x00050001
13.4 Memory Write Functionality
A total of 6 PMBus command bytes have been assigned for write functionality in the UCD3138 Boot ROM.
Each of these write-based PMBus messages utilizes a write format, in which the PMBus Master provides
an address, the command byte and data bytes to the PMBus Slave (UCD3138).
13.4.1 Write 4 Bytes
The Write 4 Bytes message writes a 32 bit word into a specified address. The Write 4 Bytes message
utilizes the PMBus write block message format. The PMBus Master initiates the message by sending the
device address, a command byte of 0xF5, a block length of 0x8, the 32-bit write address location, four
data bytes and a PEC byte. The Boot ROM interprets the command byte and stores the word at the write
address specified by the incoming message.
Start
Device Address & R/W
(0x16)
Command Byte (0xF5)
Block Size (0x08)
Write Address[31:24]
Write Address[24:16]
Write Address[15:8]
Write Address[7:0]
Data[31:24]
Data[23:16]
Data[15:8]
Data[7:0]
PEC
Stop
The Write 4 Bytes message is normally very quick, and no PMBus delay is required. However, the Write 4
Bytes message can be used for writing to data and program flash, simply by writing to the appropriate
address. In this case, 50 µsec should be allowed before starting the next message.
13.4.2 Write 16 Bytes
The Write 16 Bytes message writes a block of 16 data bytes starting at a specified address. The Write 16
Bytes message utilizes the PMBus write block message format. The PMBus Master initiates the message
by sending the device address, a command byte of 0xF4, a block length of 0x14, the 32-bit write address
location, sixteen data bytes and a PEC byte. The Boot ROM interprets the command byte and stores the
data bytes starting at the write address specified by the incoming message.
Start
Device Address & R/W
(0x16)
Command Byte (0xF4)
Block Size (0x14)
Write Address[31:24]
Write Address[24:16]
Write Address[15:8]
Write Address[7:0]
Data Byte[0]
Data Byte[1]
Data Byte[2]
Data Byte[3]
Data Byte[4]
Data Byte[5]
Data Byte[6]
Data Byte[7]
Data Byte[8]
Data Byte[9]
Data Byte[10]
Data Byte[11]
Data Byte[12]
Data Byte[13]
Data Byte[14]
Data Byte[15]
PEC
Stop