Memory Read Functionality
442
SNIU028A – February 2016 – Revised April 2016
Copyright © 2016, Texas Instruments Incorporated
Boot ROM and Boot Flash
13.2.2 Read 4 Bytes
Boot ROM will interpret the command byte, read a word from the read address and complete the message
by sending the 4 data bytes and a PEC.
Start
Device Address & R/W
(0x16)
Command Byte (0xFA)
Repeated Start
Device Address & R/W
(0x17)
Block Size (0x04)
Data[31:24]
Data[23:16]
Data[15:8]
Data[7:0]
PEC
Stop
13.2.3 Read 16 Bytes
The Read 16 Bytes message reads 16 bytes from the address configured as the read address. The
master initiates the Read Block message by sending a device address and a command byte of 0xF9. The
Boot ROM will interpret the command byte, read 16 bytes starting at the read address and complete the
message by sending the 16 data bytes and a calculated PEC byte.
Start
Device Address & R/W (0x16)
Command Byte (0xF9)
Repeated Start
Device Address & R/W (0x17)
Block Size (0x10)
Byte[0]
Byte[1]
Byte[2]
Byte[3]
Byte[4]
Byte[5]
Byte[6]
Byte[7]
Byte[8]
Byte[9]
Byte[10]
Byte[11]
Byte[12]
Byte[13]
Byte[14]
Byte[15]
PEC
Stop
13.2.4 Read Next 16 Bytes
The Read Next 16 Bytes message reads a block of data (16 bytes) from the previous read address. It is
provided so that multiple memory reads do not require multiple Configure Read Address Commands. A
Read Next Block message must be preceded by either a Read Block Message or a Read Next Block
Message. The read address is initially configured prior to the Read Block message that starts the data
transfer. The master initiates the Read Next Block message by sending a device address and a command
byte of 0xF8. The Boot ROM will interpret the command byte, read 16 bytes starting at the new read
address and complete the message by sending the 16 data bytes and a calculated PEC byte. After this
message, the read address is automatically incremented by 16.
Start
Device Address & R/W (0x16)
Command Byte (0xF9)
Repeated Start
Device Address & R/W (0x17)
Block Size (0x10)
Byte[0]
Byte[1]
Byte[2]
Byte[3]
Byte[4]
Byte[5]
Byte[6]
Byte[7]
Byte[8]
Byte[9]
Byte[10]
Byte[11]
Byte[12]
Byte[13]
Byte[14]
Byte[15]
PEC
Stop
13.3 Read Version
The Read Version message reads the current ROM version from the Boot ROM. The USB/PMBus adapter
initiates the Read Version message by sending a device address and a command byte of 0xEC. The Boot
ROM will interpret the command byte and return the block size of 4 bytes, the current version number and
the PEC byte for the message. The current version for the version of UCD3138 should be 0x00030002.
Start
Device Address & R/W (0x16)
Command Byte (0xF9)
Repeated Start
Device Address & R/W (0x17)
Block Size (0x04)
Version[31:24]
Version[32:16]
Version[15:8]
Version[7:0]
PEC
Stop