MSC8144E Reference Manual, Rev. 3
20-18
Freescale
Semiconductor
UART
20.2.4 Parity Error
The UART can be configured to enable parity check via the Parity Enable (PE) bit in the SCICR.
The parity type (SCICR[PT]) determines whether to check for even or odd parity. The Parity
Error Flag, SCISR[PF], is set when the parity enable bit is set and the parity of the received
character does not match the PT bit. Clear SCISR[PF] by reading the SCISR and then reading
SCIDR.
20.2.5 Break Characters
The UART recognizes a break character as a start bit followed by 8 or 9logic 0 data bits and a
logic 0 stop bit. Receiving a break character has the following effects on UART registers:
1.
The framing error flag (SCISR[FE]) is set.
2.
The receive data register full flag (SCISR[RDRF]) is set.
Note:
Once the RDRF flag is cleared after being set by a break character, a valid frame must
set the RDRF flag again before another break character can set it again.
3.
The SCIDR is cleared.
4.
The overrun flag (OR), noise flag (NF), parity error flag (PF), or the receiver active flag
(RAF) is set (see the discussion in Section 20.6).
20.2.6 Baud-Rate Tolerance
A transmitting device may be operating at a baud rate below or above the receiver baud rate.
Accumulated bit time misalignment can cause one of the three stop bit data samples (RT8, RT9,
and RT10) to fall outside the actual stop bit. A noise error occurs if the RT8, RT9, and RT10
samples are not all the same logical values. A framing error occurs if the receiver clock is
misaligned so that the majority of the RT8, RT9, and RT10 stop bit samples are a logic zero. In
most applications, the baud-rate tolerance is much more than the degree of misalignment that is
likely to occur.
As the receiver samples an incoming frame, it resynchronizes the RT clock on any valid falling
edge within the frame. Resynchronization within frames corrects a misalignment between
transmitter bit times and receiver bit times.
Summary of Contents for MSC8144E
Page 1: ...MSC8144E Reference Manual Quad Core Media Signal Processor MSC8144ERM Rev 3 July 2009 ...
Page 48: ...MSC8144E Reference Manual Rev 3 xlviii Freescale Semiconductor ...
Page 86: ...MSC8144E Reference Manual Rev 3 1 38 Freescale Semiconductor Overview ...
Page 168: ...MSC8144E Reference Manual Rev 3 3 60 Freescale Semiconductor External Signals ...
Page 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Page 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Page 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Page 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Page 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Page 1070: ...MSC8144E Reference Manual Rev 3 21 28 Freescale Semiconductor Timers ...