DocID018909 Rev 11
961/1731
RM0090
Universal synchronous asynchronous receiver transmitter (USART)
1010
Figure 296. USART block diagram
W
a
ke
u
p
u
nit
Receiver
control
SR
Tr
a
n
s
mit
control
TXE TC RXNE IDLE ORE NF
FE
U
S
ART
control
interr
u
pt
CR1
M
WAKE
Receive d
a
t
a
regi
s
ter (RDR)
Receive
S
hift Regi
s
ter
Re
a
d
Tr
a
n
s
mit d
a
t
a
regi
s
ter (TDR)
Tr
a
n
s
mit
S
hift Regi
s
ter
Write
S
W_RX
TX
(D
a
t
a
regi
s
ter) DR
Tr
a
n
s
mitter
clock
Receiver
clock
Receiver r
a
te
Tr
a
n
s
mitter r
a
te
f
PCLKx(x=1,2)
control
control
/
[
8
x (2 - OVER
8
)]
Convention
a
l b
au
d r
a
te gener
a
tor
S
BK
RWU
RE
TE
IDLE
RXNE
TCIE
TXEIE
CR1
UE
PCE
P
S
PEIE
PE
PWDATA
IRLP
S
CEN
IREN
DMAR
DMAT
U
S
ART Addre
ss
CR2
CR3
IrDA
S
IR
ENDEC
block
LINE
CKEN CPOL CPHA LBCL
S
CLK control
SCLK
CR2
GT
S
TOP[1:0]
NACK
DIV_M
a
nti
ssa
15
0
RE
USART_BRR
/
U
S
ARTDIV
TE
HD
(CPU or DMA)
(CPU or DMA)
PRDATA
H
a
rdw
a
re
flow
controller
CT
S
LBD
RX
nRT
S
nCT
S
GTPR
P
S
C
IE
IE
DIV_Fr
a
ction
4
U
S
ARTDIV = DIV_M
a
nti
ssa
+ (DIV_Fr
a
ction /
8
× (2 – OVER
8
))
S
AMPLING
CR1
OVER
8
DIVIDER
a
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