SPRUII0F May 2019 – June 2024 TMS320F28384D , TMS320F28384D-Q1 , TMS320F28384S , TMS320F28384S-Q1 , TMS320F28386D , TMS320F28386D-Q1 , TMS320F28386S , TMS320F28386S-Q1 , TMS320F28388D , TMS320F28388S
The MAC transmitter can be programmed to enter and exit LPI IDLE mode automatically based on whether it is IDLE for a specific period of time or has a packet to transfer. These modes are enabled and controlled by MAC_LPI_Control_Status register.
When LPITXA (Bit[19]) and LPITXEN (Bit[16]) of MAC_LPI_Control_Status register are set, the MAC transmitter enters the LPI IDLE state when the MAC transmit path (including the MTL layers and DMA layers) are idle. The MAC transmitter exits the LPI IDLE state and clears the LPITXEN bit as soon as any of functions in the TX path (DMA, MTL or MAC) becomes non-idle due to initiation of a packet transfer.
In addition to the above, when Bit[20] (LPIATE) is also set, the MAC transmitter enters the LPI IDLE state only if the Transmit path remains in idle state (no activity) for the time period indicated by the value in MAC_LPI_Entry_Timer. In this mode also, the MAC transmitter exits the LPI IDLE state as soon as any of the functions becomes non-idle. However, the LPITXEN bit is not cleared but remains active so that reentry to the LPI IDLE state is possible without any software intervention when the MAC becomes idle again.
When both LPIATE and LPITXA bits are cleared, you can directly control the entry and exit of LPI IDLE state by programming the LPITXEN bit.