SPRUJ53B April 2024 – September 2024 TMS320F28P550SJ , TMS320F28P559SJ-Q1
The PMBus module provides support for extended commands which allow for an extra 256 command codes. By asserting the EXT_CMD bit within the PMBCCR register, two command bytes are transmitted on the message protocol. Extended commands can be added to the Write Byte and Write Word (Figure 27-25) and the Read Byte and Read Word (Figure 27-26) protocols. Operation of the PMBus module in extended command mode is similar to these formats. In programming the write data or first part of the read message, the second command byte is loaded into bits 15-8 of the PMBTXBUF register with the remaining data bytes. The remaining operation of the module is identical to the previous protocols, except for the inclusion of a Repeated Start condition and target address in the write messages. No support is required by firmware for these additional bytes in the write messages. The module interprets the EXT_CMD bit and makes the appropriate format changes.