NXP Semiconductors K32 L2A Series, Reference Manual, Page: 576 / 1379

Table 22-4. UART Transmit Configuration
Register Value Comments
transfer, use the Shifter Status Flag to
indicate when data can be written using
interrupt or DMA request. Can support
MSB first transfer by writing to
SHIFTBUFBBS[7:0] register instead.
22.4.2 UART Receive
UART receive can be supported using one Timer, one Shifter and one Pin (two Timers
and two Pins if supporting RTS). The start and stop bit verification is handled
automatically and multiple transfers can be supported using the DMA controller. The
timer status flag can be used to indicate when the stop bit of each word is received.
Triple voting of the received data is not supported by FlexIO, data is sampled only once
in the middle of each bit. Another timer can be used to implement a glitch filter on the
incoming data, another Timer can also be used to detect an idle line of programmable
length. Break characters will cause the error flag to set and the shifter buffer register will
return 0x00.
FlexIO does not support automatic verification of parity bits.
Table 22-5. UART Receiver Configuration
Register Value Comments
SHIFTCFGn 0x0000_0032 Configure start bit of 0 and stop bit of 1.
SHIFTCTLn 0x0080_0001 Configure receive using Timer 0 on
negedge of clock with input data on Pin
0. Can invert input data by setting
PINPOL.
TIMCMPn 0x0000_0F01 Configure 8-bit transfer with baud rate of
divide by 4 of the FlexIO clock. Set
TIMCMP[15:8] = (number of bits x 2) - 1.
Set TIMCMP[7:0] = (baud rate divider /
2) - 1.
TIMCFGn 0x0204_2422 Configure start bit, stop bit, enable on
pin posedge and disable on compare.
Enable resynchronization to received
data with TIMOUT=0x2 and
TIMRST=0x4.
TIMCTLn 0x0000_0081 Configure dual 8-bit counter using
inverted Pin 0 input.
SHIFTBUFn Data to receive Received data can be read from
SHIFTBUFBYS[7:0], use the Shifter
Status Flag to indicate when data can be
Application Information
K32 L2A Reference Manual, Rev. 2, 01/2020
576 NXP Semiconductors