GD32A50x User Manual
498
factor is twice as the prescaler value.
00000: Reserved - do not program this value.
00001: divides the source clock by 2.
00010: divides the source clock by 4.
00011: divides the source clock by 6.
...
This bit field cannot be written when the USART is enabled (UEN=1).
19.4.6.
Receiver timeout register (USART_RT)
Address offset: 0x14
Reset value: 0x0000 0000
This register has to be accessed by word (32-bit).
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
BL[7:0]
RT[23:16]
rw
rw
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RT[15:0]
rw
Bits
Fields
Descriptions
31:24
BL[7:0]
Block Length
These bits specify the block length in smartcard T=1 Reception. Its value equals
the number of information char the length of the Epilogue Field (1-LEC/2-
CRC) - 1.
This value, which must be programmed only once per received block, can be
programmed after the start of the block reception (using the data from the LEN
character in the Prologue Field). The block length counter is reset when TBE=0 in
smartcard mode.
In other modes, when REN=0 (receiver disabled) and/or when the EBC bit is
written to 1, the Block length counter is reset.
23:0
RT[23:0]
Receiver timeout threshold.
These bits are used to specify receiver timeout value in terms of number of baud
clocks.
In standard mode, the RTF flag is set if no new start bit is detected for more than
the RT value after the last received character.
In smartcard mode, the CWT and BWT are implemented by this value. In this
case, the timeout measurement is started from the start bit of the last received
character.
These bits can be written on the fly. The RTF flag will be set if the new value is
lower than or equal to the counter. These bits must only be programmed once per
received character.