Enhanced Serial Communication Interface (eSCI)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
Freescale Semiconductor
24-31
Preliminary
core via the slave bus. The MDIS bit is intended to be used when the module is not required in the
application.
The module disable bit (ESCIx_CR2[MDIS]) in the eSCI control register 2 can be used to turn off the
eSCI. This saves power by stopping the eSCI core from being clocked.
By default the eSCI is disabled (ESCIx_CR2[MDIS]=1).
24.4.7.1
Stop Mode
The eSCI is inactive during stop mode (SIU_HLT[ESCI_
x
] = 1)for reduced power consumption.To avoid
corrupting data, the eSCI will prevent the system from entering Stop mode before the current operation is
completed. In SCI mode the eSCI will wait until the current byte has been received or transmitted. It is
possible that a received byte will nevertheless be corrupted, so the first byte in the eSCI after waking up
from Stop mode could be invalid. To help prevent byte corruption, first enter doze mode, then go into stop
mode.
In LIN mode the eSCI will wait at least until the current byte has been received or transmitted before
entering stop mode. If the LIN FSM has some more data to receive or transmit which does not require
processor access (CRC and checksum bytes or last transmit byte of a frame) the eSCI will delay stop mode
until these operations are complete, too.
If a LIN frame was aborted, the DMA controller will be out of sync, and the channel needs to be restarted
after leaving stop mode.
24.4.8
Interrupt Operation
24.4.8.1
Interrupt Sources
There are several interrupt sources that can generate an eSCI interrupt to the CPU. They are listed with
details and descriptions in
).
The eSCI originates interrupt requests only. The following sections describe how the eSCI generates a
request and how the MCU acknowledges that request. The eSCI has a single interrupt line (eSCI interrupt
signal, active high operation) only and all the following interrupts, when generated, are ORed together and
issued through that port.
24.4.8.2
Interrupt Flags
24.4.8.2.1
TDRE Description
The transmit data register empty (TDRE) interrupt is set high by the eSCI when the transmit shift register
receives data, 8 or 9 bits, from the eSCI data register, ESCI
x
_DR. A TDRE interrupt indicates that the
transmit data register (ESCI
x
_DR) is empty and that a new data can be written to the ESCI
x
_DR for
transmission. The TDRE bit is cleared by writing a 1 to the TDRE bit location in the ESCI
x
_SR.