MCIMX27 Datasheet, PDF (921/1650 Pages) Freescale Semiconductor, Inc – Multimedia Applications Processor

Universal Asynchronous Receiver/Transmitters (UART)
Table 28-22. RTS Edge Triggered Interrupt Truth Table (continued)
RTS RTSEN
1–>0
1
0–>1
1
RTEC [1]
1
1
RTEC [0]
X
X
RTSF
1
1
Interrupt Occurs On:
Either edge
Either edge
ipi_uart_mint_b
0
0
There is another RTS interrupt that is not programmable, however it asserts the RTS Delta (RTSD) bit
when the RTS pin changes state. The status bit RTSD asserts the ipi_uart_mint_b interrupt when the RTS
delta interrupt enable = 1. This is an asynchronous interrupt. The RTSD bit is cleared by writing 1 to it.
Writing 0 to the RTSD bit has no effect.
28.4.3.3 Clear To Send (CTS)
This output pin serves two purposes. Normally, the receiver indicates that it is ready to receive data by
asserting this pin (low). When the CTS trigger level is programmed to trigger at 32 characters received and
the receiver detects the valid start bit of the 33 character, it de-asserts this pin.
28.4.3.4 Programmable CTS Deassertion
The CTS output can also be programmed to deassert when the RxFIFO reaches a certain level. Setting the
CTS trigger level (UCR4[15:10]) at any value less than 32 deasserts the CTS pin on detection of the valid
start bit of the N + 1 character (where N is the trigger level setting). However, the receiver continues to
receive characters until the RxFIFO is full.
28.4.3.5 TXD—UART Transmit
This is the transmitter serial output. When operating in normal mode, NRZ encoded data is output. When
operating in infrared mode, a 3/16 bit-period pulse is output for each 0 bit transmitted, and no pulse is
output for each 1 bit transmitted. For RS-232 applications, this pin must be connected to an RS-232
transmitter.
28.4.3.5.1 RXD—UART Receive
This is the receiver serial input. When operating in normal mode, NRZ encoded data is expected. When
operating in infrared mode, a narrow pulse is expected for each 0 bit received and no pulse is expected for
each 1 bit received. External circuitry must convert the IR signal to an electrical signal. RS-232
applications require an external RS-232 receiver to convert voltage levels.
MCIMX27 Multimedia Applications Processor Reference Manual, Rev. 0.2
Freescale Semiconductor
28-33