MC68HC16Z1CAG16 Datasheet, PDF (257/500 Pages) Freescale Semiconductor, Inc – M68HC16Z Series users manual

Freescale Semiconductor, Inc.
Pin
Transmit data
Receive data
Mode
TXDA
TXDB
RXDA
RXDB
Table 10-5 SCI Pins
SCI Function
Serial data output from SCIA (TE = 1)
Serial data output from SCIB (TE = 1)
Serial data input to SCIA (RE = 1)
Serial data input to SCIB (RE = 1)
Port I/O Signal
PMC7
PMC5
PMC6
PMC4
10.4.3 Receive Data Pins (RXDA, RXDB)
RXDA and RXDB are the serial data inputs to the SCIA and SCIB interfaces, respec-
tively. Each pin is also available as a general-purpose I/O pin when the RE bit in
SCCR1 of the associated SCI submodule is cleared. When used for general-purpose
I/O, RXDA and RXDB may be configured either as input or output as determined by
the RXDA and RXDB bits in the MDDR.
10.4.4 Transmit Data Pins (TXDA, TXDB)
When used for general-purpose I/O, TXDA and TXDB can be configured either as in-
put or output as determined by the TXDA and TXDB bits in the MDDR. The TXDA and
TXDB pins are enabled for SCI use by setting the TE bit in SCCR1 of each SCI inter-
face.
10.4.5 SCI Operation
SCI operation can be polled by means of status flags in the SCSR, or interrupt-driven
operation can be employed by means of the interrupt-enable bits in SCCR1.
10.4.5.1 Definition of Terms
Data can be transmitted and received in a number of formats. The following terms con-
cerning data format are used in this section:
• Bit-Time — The time required to transmit or receive one bit of data, which is equal
to one cycle of the baud frequency.
• Start Bit — One bit-time of logic zero that indicates the beginning of a data frame.
A start bit must begin with a one-to-zero transition and be preceded by at least
three receive time samples of logic one.
• Stop Bit — One bit-time of logic one that indicates the end of a data frame.
• Frame — A complete unit of serial information. The SCI can use 10-bit or 11-bit
frames.
• Data Frame — A start bit, a specified number of data or information bits, and at
least one stop bit.
• Idle Frame — A frame that consists of consecutive ones. An idle frame has no
start bit.
• Break Frame — A frame that consists of consecutive zeros. A break frame has
no stop bits.
M68HC16 Z SERIES
USER’S MANUAL
MULTICHANNEL COMMUNICATION INTERFACE
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