
Low-power universal asynchronous receiver transmitter (LPUART)
RM0453
1210/1454
RM0453 Rev 2
Figure 333. LPUART word length programming
36.4.4
LPUART FIFOs and thresholds
The LPUART can operate in FIFO mode.
The LPUART comes with a Transmit FIFO (TXFIFO) and a Receive FIFO (RXFIFO). The
FIFO mode is enabled by setting FIFOEN bit (bit 29) in LPUART_CR1 register.
Since the maximum data word length is 9 bits, the TXFIFO is 9-bit wide. However the
RXFIFO default width is 12 bits. This is due to the fact that the receiver does not only store
MS33194V2
Bit0
Bit1
Bit2
Bit3
Bit4
Bit5
Bit6
Bit7
Bit8
Start
bit
Stop
bit
Next
Start
bit
Idle frame
9-bit word length (M = 01 ), 1 Stop bit
Possible
Parity
bit
Break frame
Data frame
Clock
**
Start
bit
Stop
bit
Start
bit
Stop
bit
Bit0
Bit1
Bit2
Bit3
Bit4
Bit5
Bit6
Bit7
Start
bit
Stop
bit
Next
Start
bit
Idle frame
8-bit word length (M = 00 ), 1 Stop bit
Possible
Parity
bit
Break frame
Data frame
Clock
**
Start
bit
Stop
bit
Start
bit
Stop
bit
Bit0
Bit1
Bit2
Bit3
Bit4
Bit5
Bit6
Start
bit
Stop
bit
Next
Start
bit
Idle frame
7-bit word length (M = 10 ), 1 Stop bit
Possible
Parity
bit
Break frame
Data frame
Clock
** LBCL bit controls last data clock pulse
**
Start
bit
Stop
bit
Start
bit
Stop
bit