SNIU028D February 2016 – September 2020 UCD3138 , UCD3138064 , UCD3138064A , UCD3138128 , UCD3138A , UCD3138A64
The Boot ROM supports a function to calculate a checksum over a portion of the address space. The PMBus Master initiates a PMBus write block message to initiate a checksum calculation within the UCD3138. The PMBus master sends the device address, a command byte of 0xEF, the starting address of the checksum calculation, the number of bytes to process and a PEC byte. Upon detection of the command byte 0xEF, the Boot ROM reads the block of memory space and calculates a checksum. This process requires less than 20 milliseconds for a 32K memory space.
Start | Device Address & R/W (0x16) | Command Byte (0xEF) | Block Size (0x08) | Start Address[31:24] |
Start Address[23:16] | Start Address[15:8] | Start Address[7:0] | Byte Count[31:24] |
Byte Count[23:16] | Byte Count[15:8] | Byte Count[7:0] | PEC | Stop |