peb20560 Infineon Technologies Corporation, peb20560 Datasheet - Page 199

• Manufacturer Part Number: peb20560
• Description: Dsp Oriented Pbx Controller Doc
• Manufacturer: Infineon Technologies Corporation

2.14.1.8
This register provides the current state of the control lines from the modem (or peripheral
device) to the CPU. In addition to this current-state information, four bits of the modem
status register provide change information. These bits are set to a logic 1 whenever a
control input from the modem changes state. They are reset to logic 0 whenever the µP
reads the modem status register.
bit
MSR
Table 2-31 shows the contents of the MSR. Details on each bit follow.
DCTS
DDSR
TERI
DDCD
CTS
DSR
RI
DCD
Semiconductor Group
Modem Status Register (MSR)
7
DCD
This bit is the delta clear to send indicator. Bit 0 indicates that the
CTS input to the chip has changed state since the last time it was
read by the CPU.
This bit is the delta data set ready indicator. Bit 1 indicates that the
DSR input to the chip has changed state since the last time it was
read by the CPU.
This bit is the trailing edge of ring indicator detector. Bit 2 indicates
that the Rl input to the chip has changed from a low to a high state.
This bit is the delta data carrier detect indicator. Bit 3 indicates that
the DCD input to the chip has changed state:
Note: Whenever bit 0, 1, 2, or 3 is set to logic 1, a modem status
This bit is the complement of the clear to send input. If bit 4 (loop) of
the MCR is set to a 1, this bit is equivalent to RTS in the MCR.
This bit is the complement of the data set ready input. If bit 4 of the
MCR is set to a 1, this bit is equivalent to DTR in the MCR.
This bit is the complement of the ring indicator input. If bit 4 of the
MCR is set to a 1, this bit is equivalent to OUT1 in the MCR.
This bit is the complement of the data carrier detect input. If bit 4 of
the MCR is set to a 1, this bit is equivalent to OUT2 in the MCR.
6
interrupt is generated.
Rl
5
DSR
4
2-153
CTS
3
DDCD
Functional Block Description
2
TERI
1
DDSR
PEB 20560
0
DCTS
2003-08