NXP Semiconductors MKW01Z128, Reference Manual

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UARTx_C4 field descriptions (continued)
Field Description
RDMAS configures the receiver data register full flag, RDRF, to generate interrupt or DMA requests if RIE
is set.
NOTE: If RIE is cleared, the RDRF DMA and RDRF interrupt request signals are not asserted when the
RDRF flag is set, regardless of the state of RDMAS.
0 If RIE is set and the RDRF flag is set, the RDRF interrupt request signal is asserted to request
interrupt service.
1 If RIE is set and the RDRF flag is set, the RDRF DMA request signal is asserted to request a DMA
transfer.
4
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
3
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
Reserved This field is reserved.
This read-only field is reserved and always has the value 0.
33.4 Functional description
The UART allows full-duplex, asynchronous, NRZ serial communication among the
MCU and remote devices, including other MCUs.
The UART comprises a baud rate generator, transmitter, and receiver block. The
transmitter and receiver operate independently, although they use the same baud rate
generator. During normal operation, the MCU monitors the status of the UART, writes
the data to be transmitted, and processes received data. The following describes each of
the blocks of the UART.
33.4.1 Baud rate generation
As shown in the figure found here, the clock source for the UART baud rate generator is
the bus-rate clock.
Baud Rate Generator
Off If [SBR12:SBR0] =0
Baud Rate =
SBR[12:0] × 16
16
Modulo Divide By
(1 through 8191)
UART Module Clock
UART Module Clock
SBR[12:0]
Divide By
16
Tx Baud Rate
Rx Sampling Clock
(16 × Baud Rate)
Figure 33-3. UART baud rate generation
Functional description
MKW01Z128 MCU Reference Manual, Rev. 3, 04/2016
660 Freescale Semiconductor, Inc.