SNIU028E February 2016 – February 2025 UCD3138 , UCD3138064 , UCD3138064A , UCD3138128 , UCD3138A , UCD3138A64
If the neither checksum matches, the Boot ROM retains control of the processor. The Boot ROM configures the chip as a PMBus Slave, so the host needs to act as a PMBus Master. The Boot ROM is always at address 11 (0x0B). It provides a set of PMBus commands which can be used to control and program the UCD3138.
These commands are:
| Boot ROM Function | Command Byte |
|---|---|
| Configure Read Address | 0xFD |
| Read 4 Bytes | 0xFA |
| Read 16 Bytes | 0xF9 |
| Read Next 16 Bytes | 0xF8 |
| Write 4 Bytes | 0xF5 |
| Write 16 Bytes | 0xF4 |
| Write Next 16 Bytes | 0xF3 |
| Mass Erase Flash | 0xF2 |
| Page Erase Flash | 0xF1 |
| Execute from Program Flash | 0xF0 |
| Calculate Checksum | 0xEF |
| Read Checksum | 0xEE |
| Read Version | 0xEC |
The read and write message names are selected to avoid confusion with the Write Word and Block Write messages in the PMBus Specification.