Functional Description
Table 19-10. Local Power-Management Features
Feature
Registers
Description
Clock autogating
UART_SYSC[0] AUTOIDLE
This bit allows local power optimization in the module by gating the
UARTi_ICLK clock on interface activity or gating the UARTi_FCLK
clock on internal activity.
Slave idle modes
UART_SYSC[4:3] IDLEMODE
Force-idle, no-idle, smart-idle, and smart-idle wakeup-capable modes
are available
Clock activity
N/A
Feature not available
Master standby
N/A
Feature not available
modes
Global wake-up
UART_SYSC[2] ENAWAKEUP
This bit enables the wake-up feature at module level.
enable
Wake-Up sources
N/A
Feature not available
enable
19.3.5 Interrupt Requests
The UART IrDA CIR module generates interrupts. All interrupts can be enabled/disabled by writing to the
appropriate bit in the interrupt enable register (IER). The interrupt status of the device can be checked at
any time by reading the interrupt identification register (IIR). The UART, IrDA, and CIR modes have
different interrupts in the UART IrDA CIR module and therefore have different IER and IIR mappings
according to the selected mode.
19.3.5.1 UART Mode Interrupt Management
19.3.5.1.1 UART Interrupts
UART mode includes seven possible interrupts prioritized to six levels.
When an interrupt is generated, the interrupt identification register (UARTi.UART_IIR) sets the
UARTi.UART_IIR[0] IT_PENDING bit to 0 to indicate that an interrupt is pending, and indicates the type of
interrupt through the UARTi.UART_IIR[5:1] bit field.
summarizes the interrupt control
functions.
Table 19-11. UART Mode Interrupts
UART_IIR[5:0]
Priority Level
Interrupt Type
Interrupt Source
Interrupt Reset Method
000001
None
None
None
None
000110
1
Receiver line
OE, FE, PE, or BI errors occur in
FE, PE, BI: Read the UART_RHR
status
characters in the RX FIFO.
register. OE: Read the UART_LSR
register.
001100
2
RX time-out
Stale data in RX FIFO
Read the UART_RHR register.
000100
2
RHR interrupt
DRDY (data ready) (FIFO
Read the UART_RHR register until the
disable)
interrupt condition disappears.
RX FIFO above trigger level
(FIFO enable)
000010
3
THR interrupt
TFE (UART_THR empty) (FIFO
Write to the UART_THR until the
disable)
interrupt condition disappears.
TX FIFO below trigger level (FIFO
enable)
000000
4
Modem status
See the UART_MSR register.
Read the UART_MSR register.
010000
5
XOFF
Receive XOFF characters/special
Receive XON character(s), if XOFF
interrupt/special
character
interrupt/read of the UART_IIR register,
character
if special character interrupt.
interrupt
100000
6
CTS, RTS, DSR
RTS pin or CTS pin or DSR
Read the UART_IIR register.
change state from active (low) to
inactive (high).
3456Universal Asynchronous Receiver/Transmitter (UART)
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated