UART Modules
MCF5213 ColdFire® Integrated Microcontroller Reference Manual, Rev. 3
21-2
Freescale Semiconductor
The serial communication channel provides a full-duplex asynchronous/synchronous receiver and
transmitter deriving an operating frequency from the internal bus clock or an external clock using the timer
pin. The transmitter converts parallel data from the CPU to a serial bit stream, inserting appropriate start,
stop, and parity bits. It outputs the resulting stream on the transmitter serial data output (U
n
TXD). See
Section 21.4.2.1, “Transmitter
.”
The receiver converts serial data from the receiver serial data input (U
n
RXD) to parallel format, checks
for a start, stop, and parity bits, or break conditions, and transfers the assembled character onto the bus
during read operations. The receiver may be polled, interrupt driven, or use DMA requests for servicing.
See
.”
NOTE
The GPIO module must be configured to enable the peripheral function of
the appropriate pins (refer to
”
) prior to configuring the UART module.
21.1.2
Features
The device contains three independent UART modules with:
•
Each clocked by an external clock or by the internal bus clock (eliminating a need for an external
UART clock)
•
Full-duplex asynchronous/synchronous receiver/transmitter
•
Quadruple-buffered receiver
•
Double-buffered transmitter
•
Independently programmable receiver and transmitter clock sources
•
Programmable data format:
— 5–8 data bits plus parity
— Odd, even, no parity, or force parity
— One, one-and-a-half, or two stop bits
•
Each serial channel programmable to normal (full-duplex), automatic echo, local loop-back, or
remote loop-back mode
•
Automatic wake-up mode for multidrop applications
•
Four maskable interrupt conditions
•
All three UARTs have DMA request capability
•
Parity, framing, and overrun error detection
•
False-start bit detection
•
Line-break detection and generation
•
Detection of breaks originating in the middle of a character
•
Start/end break interrupt/status
21.2
External Signal Description
shows the external and internal signal groups.
