MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
21-34
Freescale Semiconductor
21.4.9.2
Interrupt Flags
21.4.9.2.1
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 one to the TDRE bit location in the ESCI
x
_SR.
21.4.9.2.2
TC Description
The transmit complete (TC) interrupt is set by the eSCI when a transmission has completed. A TC interrupt
indicates that there is no transmission in progress. TC is set high when the TDRE flag is set and no data,
preamble, or break character is being transmitted. When TC is set, the TXD pin becomes idle (logic 1).
The TC bit is cleared by writing a one to the TC bit location in the ESCI
x
_SR.
21.4.9.2.3
RDRF Description
The receive data register full (RDRF) interrupt is set when the data in the receive shift register transfers to
the eSCI data register. An RDRF interrupt indicates that the received data has been transferred to the eSCI
data register and that the received data can now be read by the MCU. The RDRF bit is cleared by writing
a one to the RDRF bit location in the ESCI
x
_SR.
21.4.9.2.4
OR Description
The overrun (OR) interrupt is set when software fails to read the eSCI data register before the receive shift
register receives the next frame. The newly acquired data in the shift register is lost in this case, but the
data already in the eSCI data registers is not affected.The OR bit is cleared by writing a one to the OR bit
location in the ESCI
x
_SR.
21.4.9.2.5
IDLE Description
The idle line (IDLE) interrupt is set when 10 consecutive logic 1s (if M = 0) or 11 consecutive logic 1s (if
M = 1) appear on the receiver input. After the IDLE is cleared, a valid frame must again set the RDRF flag
before an idle condition can set the IDLE flag.
The IDLE bit is cleared by writing a one to the IDLE bit
location in the ESCI
x
_SR.
21.4.9.2.6
PF Description
The interrupt is set when the parity of the received data is not correct. PF is cleared by writing it with 1.
21.4.9.2.7
FE Description
The interrupt is set when the stop bit is read as a 0; which violates the SCI protocol. FE is cleared by writing
it with 1.
21.4.9.2.8
NF Description
The NF interrupt is set when the eSCI detects noise on the receiver input.
Summary of Contents for MPC5553
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