SPRUJ53B April 2024 – September 2024 TMS320F28P550SJ , TMS320F28P559SJ-Q1
The Write Byte and Write Word messages (Figure 27-5) consist of a device address, a command byte, transmitted data bytes, and an optional PEC byte. Write Byte messages include a single byte, while the Write Word messages support transmission of 2 bytes to the corresponding target module. Similar to the Send Byte protocol, the PMBCCR register is configured to send 1 or 2 bytes, the CMD_EN bit is set to enable command byte transmission and the optional PEC_EN bit is set.
With the command byte transmission enabled, the format of the PMBTXBUF register differs from the Send Byte protocol. In bits 7-0, the firmware must program the command byte to be sent to the target. The data bytes are programmed into bits 15-8 and bits 23-16.
After programming the PMBCCR register, the PMBus module transmits the Write Byte/Word message. The firmware can wait for an End of Message interrupt from the module to verify the accuracy of the message transmission. The PMBSTS register indicates if the target acknowledged the message properly.