SNIU028D February 2016 – September 2020 UCD3138 , UCD3138064 , UCD3138064A , UCD3138128 , UCD3138A , UCD3138A64
A Send Byte message consists of the device address, a single data byte and an optional PEC byte. To initiate a Send Byte message, the data byte to be transmitted to the slave is loaded into bits 7-0 of the Transmit Data Register. The Master Control Register is configured with the device address. To transmit a PEC byte with the message, the PEC_EN bit within the Master Control Register is asserted high when the address is programmed.
After programming the Master Control Register, the PMBus Interface initiates the Send Byte message onto the PMBus. The firmware can wait for an End of Message interrupt from the PMBus Interface. Upon receipt of the EOM interrupt, the Status Register is read to verify the slave properly acknowledged the transmitted data.