
15-2
MCF5249UM
MOTOROLA
Programmable channel modes:
–
Normal (full duplex)
–
Automatic echo
–
Local loopback
–
Remote loopback
Automatic wakeup mode for multidrop applications
Four maskable interrupt conditions
Parity, framing, break, 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
15.1.1
SERIAL COMMUNICATION CHANNEL
The communication channel provides a full duplex asynchronous/synchronous receiver and transmitter
using an operating frequency derived from the system clock or from an external clock tied to the TIN pin.
The transmitter accepts parallel data from the CPU; converts it to a serial bit stream; inserts the
appropriate start, stop, and optional parity bits; then outputs a composite serial data stream on the channel
The receiver accepts serial data on the channel receiver serial data input (RxD); converts it to parallel
format; checks for a start bit, stop bit, parity (if any), or any error condition; and transfers the assembled
character onto the bus during read operations. The receiver can be polled or interrupt driven. Refer to
15.1.2
BAUD-RATE GENERATOR/TIMER
The 16-bit timer, clocked by the system clock, can function as an asynchronous x16 clock. In addition, an
external clock can be tied to one of the TIN pins of a MCF5249 timer for use as a synchronous or
asynchronous clocking source for the UART. The baud-rate timer is part of each UART and not related to
the ColdFire timer modules.
15.1.3
INTERRUPT CONTROL LOGIC
An internal interrupt request signal (IRQ) notifies the MCF5249 interrupt controller of an interrupt condition.
The output is the logical NOR of all (as many as four) unmasked interrupt status bits in the UART Interrupt
Status Register (UISR). The UART Interrupt Mask Register (UIMR) can be programmed to determine
which interrupts will be valid in the UISR.
The UART module interrupt level in the MCF5249 interrupt controller is programmed external to the UART
module. The UART can be configured to supply the vector from the UART Interrupt Vector Register (UIVR)
or program the SIM to provide an autovector when a UART interrupt is acknowledged.
The interrupt level, priority within the level, and autovectoring capability can also be programmed in the
SIM register ICR_U1.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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