SNIU028D February 2016 – September 2020 UCD3138 , UCD3138064 , UCD3138064A , UCD3138128 , UCD3138A , UCD3138A64
In ROM mode, the flash is programmed via PMBus commands. The ROM offers several PMBus commands for memory examine and modify, and for controlling program execution. For a complete description, see the UCD3138 Boot ROM Reference Manual.
Normally the PMBus commands are issued by the TI supplied GUI running on a PC (FUSION_DIGITAL_POWER_DESIGNER), or by a third party Flash programmer, so the process is invisible to the user.
First the Flash is erased using either one Mass Erase command or many Page Erase commands. Erasing the Flash sets all the bits in the Flash to 1. Next the Flash is written to using Write Block commands. Then the Flash contents can be verified using Read Block commands. Finally an Execute Program command is used to start the Flash program.