MCCIRM Freescale Semiconductor / Motorola, MCCIRM Datasheet - Page 62

• Manufacturer Part Number: MCCIRM
• Description: MCCIRM Multi-Channel Communications Interface Reference Manual
• Manufacturer: Freescale Semiconductor / Motorola

SCI Submodule
5.5 Parity Checking
5.6 Baud Clock
Reference Manual
62
The parity type (PT) bit in SCCR1 selects even (PT = 0) or odd (PT = 1)
parity. PT affects received and transmitted data. The parity enable (PE)
bit in SCCR1 determines whether parity checking is enabled (PE = 1) or
disabled (PE = 0). When PE is set, the MSB in a frame is used for the
parity function. For transmitted data, a parity bit is generated; for
received data, the parity bit is checked. When parity checking is enabled,
the parity flag (PF) in the SCI status register (SCSR) is set if a parity error
is detected.
The SCI baud clock is programmed by writing a 13-bit value to the baud
rate (BR) field in SCI control register 0 (SCCR0). The baud clock is
derived from the MCU system clock by a modulus counter. Writing a
value of 0 to BR disables the baud rate generator.
Baud clock rate is:
where BR is in the range {1, 2, 3, . . . 8191}. As the preceding equation
indicates, the baud rate depends on the values for both BR and the
system clock. For a 16.78-MHz system clock,
baud rates for different values of BR. The maximum baud rate with this
system clock speed is 524 Kbaud.
The SCI receiver operates asynchronously. To synchronize with an
incoming data stream, the SCI baud clock generator produces a receive
time (RT) sampling clock with a frequency 16 times that of the SCI baud
clock. The SCI determines the position of bit boundaries from transitions
within the received waveform and adjusts sampling points to the proper
positions within the bit period. Refer to
Synchronization
Freescale Semiconductor, Inc.
For More Information On This Product,
SCI baud clock rate = system clock/(32 x BR)
Go to: www.freescale.com
SCI Submodule
for more information.
Multichannel Communication Interface — Rev. 1.0
5.7.11 Frame Detection and
Table 5-4
shows sample
MOTOROLA