SPRUJ53B April 2024 – September 2024 TMS320F28P550SJ , TMS320F28P559SJ-Q1
To configure the module, write a clock divider to the PMBCTRL register's CLKDIV field to produce a bit clock frequency with respect to the module's configured speed. To activate target mode, set the TARGET_EN bit in the PMBCTRL register. Next, set up the PMBTCR register. The following options are configurable:
Manual acknowledgment is done by writing a one to the PMBACK register. Even with automatic acknowledgment, some writes to PMBACK are required. If the message (not including the address) is longer than 4 bytes, each packet of 4 bytes much be acknowledged. The PMBus module stretches the clock (hold the clock low) until an ACK is issued. The module then pulls the data line low and releases the clock, providing the ACK signal to the controller.
If the complete message or the last part of the message is less than 4 bytes (or the RX_BYTE_ACK_CNT limit), do not write to PMBACK.
Writing a zero to the PMBACK bit sends a NACK. This can only be done when the module is waiting for an acknowledgment. If a zero is written at any other time, the NACK is issued during the next message.