Device
UART3
CIR
uart3_rx_irrx
uart3_cts_rctx
uart3_rts_sd
IrDA transceiver
RXD
RC
SD/MODE
IRRX
RCTX
SD
108-004
Public Version
UART/IrDA/CIR Environment
www.ti.com
Figure 19-4. CIR System Overview
19.2.4 UART Interface Description
19.2.4.1 UART Interface Description
describes the UART interface.
Table 19-3. UART I/O Pin Description
Signal
I/O
(1)
Description
Reset
UART Modem Signals
uarti_rx
I
Serial data input
Unknown
uarti_tx
O
Serial data output
1
uarti_cts
I
Clear to send (UART1, UART2 and UART3 only)
Unknown
Active-low modem status signal. Reading the
UARTi.
[4] NCTS_STS bit checks the condition of
uarti_cts. Reading the UARTi.
[0] CTS_STS bit checks
a change of state of uarti_cts since the last read of the modem
status register. The auto-nCTS mode uses uarti_cts to control the
transmitter.
uarti_rts
O
Request to send (UART1, UART2 and UART3 only)
1
When active (low), the module is ready to receive data. Setting
the UARTi.
[1] RTS bit activates uarti_rts, which
becomes inactive as the result of a module reset, loopback mode,
or clearing the UARTi.
[1] RTS bit. In auto-RTS mode,
uarti_rts becomes inactive as a result of the receiver threshold
logic.
(1)
I = Input, O = Output
19.2.4.2 UART Protocol and Data Format
The UART device operates in three modes:
•
UART 16x mode (
≤
230.4K bits/s)
•
UART 16x mode with autobauding (
≤
1200 bits/s and
≤
115.2K bits/s)
•
UART 13x mode (
≥
460.8K bits/s)
CAUTION
To be used as a UART, the operating mode must be programmed appropriately
in the UARTi.
[2:0] MODE_SELECT field to select the UART, IrDA,
or CIR mode.
The UART uses a wired interface for serial communication with a remote device.
2874
UART/IrDA/CIR
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated