NXP Semiconductors PXN2020, Reference Manual, Page: 993 / 1376

Enhanced Serial Communication Interface (eSCI)
PXN20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor 31-3
31.1.3 Modes of Operation
The SCI module has two functional operational modes, SCI and LIN mode, and low power modes. The
availability of register bits and fields depends on the selected operational mode.
31.1.3.1 SCI Mode
The SCI mode is the default functional operational mode and is described in Section 31.4.5, SCI Mode.
31.1.3.2 LIN Mode
The LIN mode is the second functional operational mode and is described in Section 31.4.6, LIN Mode.
31.1.3.3 Disabled Mode
In the Disabled mode, the eSCI module indicates to the clocking system that all module clocks can be
turned off. The eSCI module is in the Disabled mode when the MDIS bit in the eSCI Control Register 2
(eSCI_CR2) is set.
31.1.3.4 Halt Mode
When the eSCI module is in halt mode, it is inactive and indicates to the system that all clocks to the eSCI
modules can be turned off.
The system requests the eSCI module to enter the halt mode when the appropriate HLT bit is set in the
SIU_HLT0 (for eSCI_A to eSCI_H) or SIU_HLT1 (for eSCI_J to eSCI_M register. When this happens,
the eSCI module performs a shut down of the ongoing transmission or reception as described in
Section 31.1.3.4.1, Entering Halt Mode from SCI Mode and Section 31.1.3.4.3, Entering Halt Mode from
LIN Mode. If the eSCI module is in halt mode and the system stop signal is de-asserted and the LIN bit
and the MDIS bit are 0, the eSCI module enters the SCI mode. The TRDE flag is set. No data will be
transmitted as long as new data is provided by the application. If the receiver is still enabled, it starts the
detection of the start bit.
The system requests the eSCI module to leave the halt mode by de-asserting the HLT bit. When this
happens, the eSCI module then enters the operational mode configured by the LIN bit and the MDIS bit.
The related sequence is described in
Section 31.1.3.4.2, Leaving Halt Mode into SCI Mode and
Section 31.1.3.4.4, Leaving Halt Mode into LIN Mode.
31.1.3.4.1 Entering Halt Mode from SCI Mode
If the eSCI module is in SCI mode and the system stop signal is asserted while a SCI frame or character
transmission is running, the eSCI module performs a shut down of the transmit process. Therefore, it
continues the ongoing frame or character transmission until the last bit of the SCI frame or character has
been transmitted. After the end of the transmission, all pending transfer requests are cleared and no more
data will be transmitted. None of the transmitter related register flags will be set.
If the eSCI module is in SCI mode and the system stop signal is asserted while a SCI frame or character
reception is running, the module stops the reception immediately. None of the receiver related register
flags will be set.