Media Local Bus (MLB)
PXN20 Microcontroller Reference Manual, Rev. 1
27-10 Freescale Semiconductor
27.3.2.2 System Status Configuration Register (SSCR)
The System Status Configuration Register (SSCR) allows system software to monitor and control the
status of the MLB network. SSCR is updated once per frame by hardware during the MLB System
Channel. Except for the bits associated with MLB lock and unlock (SSCR[SDMU] and SSCR[SDML]),
the bits of the SSCR register are not valid until the MLB is locked to the MLB interface. System software
must service status events before the start of the next MLB frame to prevent the current frame status from
being lost.
MRS MLB Software Reset. When set, resets the MLB physical and link layer logic. Hardware clears this bit automatically.
0 MLB device is not reset by software.
1 MLB device is reset by software.
MDA
[8:1]
MLB Device Address. Determines the unique DeviceAddress (DA) for the MLB Device. DeviceAddresses are used
by the system channel MlbScan command.
DA[15:0] = { 7’h00, MDA[8:1], 1’b0 }
Offset: MLB_BASE + 0x0004 Access: User read/write
0123456789101112131415
R 0 0 0 0 0 00000000000
W
Reset0000000000000000
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
R 0 0000000
SSRE
SDMU SDML SDSC SDCS SDNU SDNL SDR
W w1c w1c w1c w1c w1c w1c w1c
Reset0000000000000000
Figure 27-3. System Status Configuration Register (SSCR)
Table 27-9. SSCR Field Descriptions
Field Description
SSRE System Service Request Enable. System software can set this bit to indicate that this MLB Device is present and
needs service. An RxStatus DeviceServiceRequest (82h) is sent in response to a MlbScan System Command from
the MLB Controller. Hardware clears this bit after the RxStatus is sent.
0 MLB device responds to System Scan Command with Device Present (80h).
1 MLB device responds to System Scan Command with Device Service Request (82h).
SDMU System Detects MLB Unlock. This bit is set to indicate that the MLB Device has unlocked from the MLB frame.
Detecting a MLB unlock generates a maskable system interrupt to system software. Once set, this bit is sticky until
cleared by software by writing a logic one to this bit.
0 MLB device has not unlocked from MLB frame.
1 MLB device has unlocked from MLB frame.
Table 27-8. DCCR Field Descriptions (continued)
Field Description
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