
Low-power universal asynchronous receiver transmitter (LPUART)
RM0453
1208/1454
RM0453 Rev 2
36.4 LPUART
functional
description
36.4.1
LPUART block diagram
Figure 332. LPUART block diagram
The simplified block diagram given in
shows two fully independent clock
domains:
•
The
lpuart_pclk
clock domain
The
lpuart_pclk
clock signal feeds the peripheral bus interface. It must be active when
accesses to the LPUART registers are required.
•
The
lpuart_ker_ck
kernel clock domain
The
lpuart_ker_ck
is the LPUART clock source. It is independent of the
lpuart_pclk
and delivered by the RCC. So, the LPUART registers can be written/read even when
the
lpuart_ker_ck
is stopped.
When the dual clock domain feature is disabled, the
lpuart_ker_ck i
s the same as the
lpuart_pclk clock.
There is no constraint between
lpuart_pclk
and
lpuart_ker_ck
:
lpuart_ker_ck
can be
faster or slower than
lpuart_pclk
, with no more limitation than the ability for the software to
manage the communication fast enough.
MSv40858V3
LPUART_TDR
LPUART_RDR
LPUART_
GTPR
LPUART_BRR
LPUART_CR3
LPUART_RQR
LPUART_CR2
RX Shift Reg
COM Controller
RxFIFO
lpuart_pclk
clock domain
LPUART
TX
RX
lpuart_ker_ck
32-bit APB
bus
LPUART_ICR
LPUART_ISR
...
TX Shift Reg
...
CTS/NSS
RTS/DE
LPUART_CR1
LPUART_
RTOR
Baudrate
generator &
orversampling
lpuart_ker_ck clock domain
DMA Interface
lpuart_pclk
lpuart_tx_dma
lpuart_rx_dma
lpuart_it
lpuart_wkup
IRQ Interface
CK
LPUART_
PRESC
lpuart_ker_ck_pres
Hardware
flow control
TxFIFO