Samsung S3C2440A - Manual (Page 323)

S3C2440A RISC MICROPROCESSOR UART
11-19
UART MODEM STATUS REGISTER
There are two UART modem status registers including UMSTAT0, UMSTAT1 in the UART block.
Register Address R/W Description Reset Value
UMSTAT0 0x5000001C R UART channel 0 Modem status register 0x0
UMSTAT1 0x5000401C R UART channel 1 Modem status register 0x0
Reserved 0x5000801C - Reserved Undef
UMSTAT0 Bit Description Initial State
Delta CTS [4] Indicate that the nCTS input to the S3C2440A has changed
state since the last time it was read by CPU.
(Refer to Figure 11-8.)
0 = Has not changed
1 = Has changed 0
Reserved [3:1] 0
Clear to Send [0] 0 = CTS signal is not activated (nCTS pin is high)
1 = CTS signal is activated (nCTS pin is low) 0
nCTS
Delta CTS
Read_UMSTAT
Figure 11-7. nCTS and Delta CTS Timing Diagram