SPRUJ53B April 2024 – September 2024 TMS320F28P550SJ , TMS320F28P559SJ-Q1
The SCI/LIN can be put in either local or global low-power mode. Global low-power mode is asserted by the system and is not controlled by the SCI/LIN. During global low-power mode, all clocks to the SCI/LIN are turned off so the module is completely inactive.
Local low-power mode is asserted by setting the POWERDOWN bit; setting this bit stops the clocks to the SCI/LIN internal logic and the module registers. Setting the POWERDOWN bit causes the SCI to enter local low-power mode and clearing the POWERDOWN bit causes SCI/LIN to exit from local low-power mode. All the registers are accessible during local power-down mode as any register access enables the clock to SCI for that particular access alone.
The wakeup interrupt is used to allow the SCI to exit low-power mode automatically when a low level is detected on the LINRX pin and also this clears the POWERDOWN bit. If wakeup interrupt is disabled, then the SCI/LIN immediately enters low-power mode whenever it is requested and also any activity on the LINRX pin does not cause the SCI to exit low-power mode.
Enabling Local Low-Power Mode During Receive and Transmit
If the wakeup interrupt is enabled and low-power mode is requested while the receiver is receiving data, then the SCI immediately generates a wakeup interrupt to clear the powerdown bit and prevents the SCI from entering low-power mode and thus completes the current reception. Otherwise, if the wakeup interrupt is disabled, then the SCI completes the current reception and then enters the low-power mode.