
DocID024597 Rev 5
RM0351
Low-power universal asynchronous receiver transmitter (LPUART)
1411
41.7 LPUART
registers
for a list of abbreviations used in register descriptions.
41.7.1 Control
register 1 (LPUART_CR1)
Address offset: 0x00
Reset value: 0x0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Res.
Res.
Res.
M1
Res.
Res.
DEAT[4:0]
DEDT[4:0]
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Res.
CMIE
MME
M0
WAKE
PCE
PS
PEIE
TXEIE
TCIE
RXNEIE IDLEIE
TE
RE
UESM
UE
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
Bits 31:29 Reserved, must be kept at reset value
Bit 28
M1
: Word length
This bit, with bit 12 (M0) determines the word length. It is set or cleared by software.
M[1:0] = 00: 1 Start bit, 8 data bits, n stop bits
M[1:0] = 01: 1 Start bit, 9 data bits, n stop bits
M[1:0] = 10: 1 Start bit, 7 data bits, n stop bits
This bit can only be written when the LPUART is disabled (UE=0).
Note: In 7-bit data length mode, the Smartcard mode, LIN master mode and Auto baud rate
(0x7F and 0x55 frames detection) are not supported.
Bit 27 Reserved, must be kept at reset value
Bit 26 Reserved, must be kept at reset value
Bits 25:21
DEAT[4:0]
: Driver Enable assertion time
This 5-bit value defines the time between the activation of the DE (Driver Enable) signal and
the beginning of the start bit. It is expressed in UCLK (USART clock) clock cycles. For more
details, refer to RS485 Driver Enable paragraph.
This bit field can only be written when the LPUART is disabled (UE=0).
Bits 20:16
DEDT[4:0]
: Driver Enable de-assertion time
This 5-bit value defines the time between the end of the last stop bit, in a transmitted
message, and the de-activation of the DE (Driver Enable) signal. It is expressed in UCLK
(USART clock) clock cycles. For more details, refer to RS485 Driver Enable paragraph.
If the LPUART_TDR register is written during the DEDT time, the new data is transmitted
only when the DEDT and DEAT times have both elapsed.
This bit field can only be written when the LPUART is disabled (UE=0).
Bit 15 Reserved, must be kept at reset value
Bit 14
CMIE
: Character match interrupt enable
This bit is set and cleared by software.
0: Interrupt is inhibited
1: A LPUART interrupt is generated when the CMF bit is set in the LPUART_ISR register.