Information
UARTx_BDL field descriptions (continued)
Field Description
The baud rate for the UART is determined by the 13 SBR fields. See Baud rate generation for details.
NOTE: • The baud rate generator is disabled until C2[TE] or C2[RE] is set for the first time after
reset.The baud rate generator is disabled when SBR = 0.
• Writing to BDH has no effect without writing to BDL, because writing to BDH puts the data
in a temporary location until BDL is written.
• When the 1/32 narrow pulse width is selected for infrared (IrDA), the baud rate fields must
be even, the least significant bit is 0. See MODEM register for more details.
45.3.3 UART Control Register 1 (UARTx_C1)
This read/write register controls various optional features of the UART system.
Addresses: UART0_C1 is 4006_A000h base + 2h offset = 4006_A002h
UART1_C1 is 4006_B000h base + 2h offset = 4006_B002h
UART2_C1 is 4006_C000h base + 2h offset = 4006_C002h
Bit 7 6 5 4 3 2 1 0
Read
LOOPS UARTSWAI RSRC M WAKE ILT PE PT
Write
Reset
0 0 0 0 0 0 0 0
UARTx_C1 field descriptions
Field Description
7
LOOPS
Loop Mode Select
When LOOPS is set, the RxD pin is disconnected from the UART and the transmitter output is internally
connected to the receiver input. The transmitter and the receiver must be enabled to use the loop
function.
0 Normal operation.
1 Loop mode where transmitter output is internally connected to receiver input. The receiver input is
determined by RSRC.
6
UARTSWAI
UART Stops in Wait Mode
0 UART clock continues to run in Wait mode.
1 UART clock freezes while CPU is in Wait mode.
5
RSRC
Receiver Source Select
This field has no meaning or effect unless the LOOPS field is set. When LOOPS is set, the RSRC field
determines the source for the receiver shift register input.
0 Selects internal loop back mode. The receiver input is internally connected to transmitter output.
1 Single wire UART mode where the receiver input is connected to the transmit pin input signal.
4
M
9-bit or 8-bit Mode Select
This field must be set when C7816[ISO_7816E] is set/enabled.
Table continues on the next page...
Chapter 45 Universal Asynchronous Receiver/Transmitter (UART)
K20 Sub-Family Reference Manual, Rev. 2, Feb 2012
Freescale Semiconductor, Inc. 1055