mc68hc916y3 Freescale Semiconductor, Inc, mc68hc916y3 Datasheet - Page 282

• Manufacturer Part Number: mc68hc916y3
• Description: Mc68hc16y3 16 Bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

12.4.3 Receive Data Pins (RXDA, RXDB)
12.4.4 Transmit Data Pins (TXDA, TXDB)
12.4.5 SCI Operation
12.4.5.1 Definition of Terms
12-18
MOTOROLA
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.
When used for general-purpose I/O, TXDA and TXDB can be configured either as
input 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
interface.
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.
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
• Start Bit — One bit-time of logic zero that indicates the beginning of a data frame.
• 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
• Data Frame — A start bit, a specified number of data or information bits, and at
• Idle Frame — A frame that consists of consecutive ones. An idle frame has no
• Break Frame — A frame that consists of consecutive zeros. A break frame has
to one cycle of the baud frequency.
A start bit must begin with a one-to-zero transition and be preceded by at least
three receive time samples of logic one.
frames.
least one stop bit.
start bit.
no stop bits.
Transmit data
Receive data
Pin
MULTICHANNEL COMMUNICATION INTERFACE
Freescale Semiconductor, Inc.
TXDA
TXDB
RXDA
RXDB
Mode
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Go to: www.freescale.com
Table 12-5 SCI Pins
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)
SCI Function
Port I/O Signal
MC68HC16Y3/916Y3
PMC7
PMC5
PMC6
PMC4
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