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Preliminary
S3C2451 RISC MICROPROCESSOR
UART
15-13
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
Specifications and information herein are subject to change without notice.
UART MODEM CONTROL REGISTER
There are three UART MODEM control registers including UMCON0 and UMCON1 in the UART block.
Register Address
R/W
Description
Reset
Value
UMCON0 0x5000000C
R/W
UART
channel
0 Modem control register
0x0
UMCON1 0x5000400C
R/W
UART
channel
1 Modem control register
0x0
UMCON2 0x5000800C
R/W
UART
channel
2 Modem control register
0x0
Reserved 0x5000C00C
–
Reserved
Undef
UMCONn Bit
Description
Initial
State
RTS trigger
Level
[7:5]
When AFC bit is enabled, these bits determine when to
inactivate(High) nRTS signal.
000 = When RX FIFO contains 63 bytes.
001 = When RX FIFO contains 56 bytes.
010 = When RX FIFO contains 48 bytes.
011 = When RX FIFO contains 40 bytes.
100 = When RX FIFO contains 32 bytes.
101 = When RX FIFO contains 24 bytes.
110 = When RX FIFO contains 16 bytes.
111 = When RX FIFO contains 8 bytes.
000
Auto Flow
Control (AFC)
[4]
0 = Disable 1 = Enable
0
Reserved
[3:1]
These bits must be 0's
00
Request to Send
[0]
If AFC bit is enabled, this value will be ignored. In this case the
S3C2451X will control nRTS automatically.
If AFC bit is disabled, nRTS must be controlled by software.
0 = 'H' level (Inactivate nRTS) 1 = 'L' level (Activate nRTS)
0
NOTES:
1.
UART 3 does not support AFC function, because the S3C2451X has no nRTS3 and nCTS3.
2. If AFC bit is enabled and Time-out bit is disabled, RTS trigger level must be lager than Rx FIFO trigger level.
3. Example ) RX interrupt mode, RTS trigger level b101(24byte), RX fifo trigger level b10(16byte).
This example shows rx fifo always have space equal or larger then 40bytes.
Fifo contains
Fifo Space
nRTS
Interrupt
24 byte
40 byte
High
-
23 byte
41 byte
Low
-
… …
Low -
17 byte
47 byte
Low
-
16 byte
48 byte
Low
Occur
15 byte
49 byte
Low
-