Texas Instruments OMAP36 Series, Technical Reference Manual

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UART/IrDA/CIR Functional Description
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19.4.4.3.3 CIR Mode Interrupt Management
19.4.4.3.3.1 CIR Interrupts
The CIR function generates interrupts that can be enabled/disabled by writing to the appropriate bit in the
interrupt enable register (UART3.
IER_REG ). The interrupt status of the device can be checked at any time
by reading the interrupt identification register (UART3. IIR_REG ).
The UART, IrDA, and CIR modes have different interrupts in the UART/IrDA/CIR module and, therefore,
different UART3.
IER_REG and UART3. IIR_REG mappings, depending on the selected mode.
Table 19-37 lists the interrupt modes to be maintained. In CIR mode, the sole purpose of the
UART3. IIR_REG [5] bit is to indicate that the last bit of infrared data was passed to the uart3_cts_rctx pin.
Table 19-37. CIR Mode Interrupts
IIR_REG Bit Interrupt Type Interrupt Source Interrupt Reset Method
Number
0 N/A for CIR mode N/A for CIR mode N/A for CIR mode
1 THR interrupt TFE ( THR_REG empty) (FIFO Write to THR_REG until interrupt condition
disable) disappears.
TX FIFO below trigger level (FIFO
enable)
2 N/A for CIR mode N/A for CIR mode N/A for CIR mode
3 N/A for CIR mode N/A for CIR mode N/A for CIR mode
4 N/A for CIR mode N/A for CIR mode N/A for CIR mode
5 TX status Transmission of the last bit of the Read IIR_REG .
frame is completed successfully.
6 N/A for CIR mode N/A for CIR mode N/A for CIR mode
7 N/A for CIR mode N/A for CIR mode N/A for CIR mode
19.4.4.3.3.2 Wake-Up Interrupts
The wake-up interrupt for the IrDA mode has the same functionality as that for the UART mode (see
Section 19.4.4.1.4.1 , Wake-Up Interrupt).
19.4.5 Power Management
19.4.5.1 UART Mode Power Management
19.4.5.1.1 Module Power Saving
In UART modes, sleep mode is enabled by setting the UARTi. IER_REG [4] SLEEP_MODE bit to 1 (when
the UARTi. EFR_REG [4] ENHANCED_EN bit is set to 1).
Sleep mode is entered when all the following conditions exist:
•
The serial data input line, uarti_rx, is idle.
• The TX FIFO and TX shift register are empty.
• The RX FIFO is empty.
• No interrupts are pending except THR interrupts.
Sleep mode is a good way to lower power consumption of the UART, but this state can be achieved only
when the UART is set in modem mode. Therefore, even if the UART has no functional key role, it must be
initialized in a functional mode to take advantage of sleep mode.
In sleep mode, the module clock and baud rate clock are stopped internally. Because most registers are
clocked using these clocks, this greatly reduces power consumption. The module wakes up when a
change is detected on the uarti_rx line, when data is written to the TX FIFO, and when there is a change
in the state of the modem input pins.
2918 UART/IrDA/CIR SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated