Visible to Intel only — GUID: iga1432671720855
Ixiasoft
Visible to Intel only — GUID: iga1432671720855
Ixiasoft
10.4.8. msr
Identifier | Title | Offset | Access | Reset Value | Description |
---|---|---|---|---|---|
msr | Modem Status Register | 0x18 | R | 0x00000000 | It should be noted that whenever bits 0, 1, 2 or 3 are set to logic one, to indicate a change on the modem control inputs, a modem status interrupt will be generated if enabled via the IER regardless of when the change occurred. Since the delta bits (bits 0, 1, 3) can get set after a reset if their respective modem signals are active (see individual bits for details), a read of the MSR after reset can be performed to prevent unwanted interrupts. |
Bit Fields | |||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 |
— | |||||||||||||||
15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
— | dcd | ri | dsr | cts | ddcd | teri | ddsr | dcts |
Bit | Name/Identifier | Description | Access | Reset |
---|---|---|---|---|
[31:8] | — | Reserved | R | 0x0 |
[7] | Data Carrier Detect (dcd) | This bit is the complement of the modem control line (dcd_n). This bit is used to indicate the current state of dcd_n. When the Data Carrier Detect input (dcd_n) is asserted it is an indication that the carrier has been detected by the modem or data set. |
R | 0x0 |
[6] | Ring Indicator (ri) | This bit is the complement of modem control line (ri_n). This bit is used to indicate the current state of ri_n. When the Ring Indicator input (ri_n) is asserted it is an indication that a telephone ringing signal has been received by the modem or data set. |
R | 0x0 |
[5] | Data Set Ready (dsr) | This bit is the complement of modem control line dsr_n. This bit is used to indicate the current state of dsr_n. When the Data Set Ready input (dsr_n) is asserted it is an indication that the modem or data set is ready to establish communications with the uart. |
R | 0x0 |
[4] | Clear to Send (cts) | This bit is the complement of modem control line cts_n. This bit is used to indicate the current state of cts_n. When the Clear to Send input (cts_n) is asserted it is an indication that the modem or data set is ready to exchange data with the uart. |
R | 0x0 |
[3] | Delta Data Carrier Detect (ddcd) | This is used to indicate that the modem control line dcd_n has changed since the last time the MSR was read. Reading the MSR clears the DDCD bit.
Note: If the DDCD bit is not set and the dcd_n signal is asserted (low) and a reset occurs (software or otherwise), then the DDCD bit will get set when the reset is removed if the dcd_n signal remains asserted.
|
RC | 0x0 |
[2] | Trailing Edge of Ring Indicator (teri) | This is used to indicate that a change on the input ri_n (from an active low, to an inactive high state) has occurred since the last time the MSR was read. Reading the MSR clears the TERI bit. |
RC | 0x0 |
[1] | Delta Data Set Ready (ddsr) | This is used to indicate that the modem control line dsr_n has changed since the last time the MSR was read. Reading the MSR clears the DDSR bit.
Note: If the DDSR bit is not set and the dsr_n signal is asserted (low) and a reset occurs (software or otherwise), then the DDSR bit will get set when the reset is removed if the dsr_n signal remains asserted.
|
RC | 0x0 |
[0] | Delta Clear to Send (dcts) | This is used to indicate that the modem control line cts_n has changed since the last time the MSR was read. Reading the MSR clears the DCTS bit.
Note: If the DCTS bit is not set and the cts_n signal is asserted (low) and a reset occurs (software or otherwise), then the DCTS bit will get set when the reset is removed if the cts_n signal remains asserted.
|
RC | 0x0 |