PPC7A Product Manual
Functional Description
8-32
1
st
Edition
FLASH Control Register (Port 0x086E)
This register provides status and control signals for the Boot sections of the FLASH devices.
When the PPC7A
is reset, this register is reset to reflect the status of the BOOT links (E8, E4 & E7),
after boot software can then override these link settings by writing to bits D5 & D7 in this register.
Status signals BOOT_ALTERNATE, BOOT_FROM_VME & BOOT_RECOVERY show the real link
settings. Signals SELECT_ALTERNATE & SELECT_RECOVERY show what image is really selected.
MSB = D0, LSB = D7
D0:
NVRAM Write Protect
0 = NVRAM is write protected
1 = Writes to NVRAM are enabled
D1:
BOOT_ALTERNATE (reflects the status of user link E8). This bit is read-only.
0 = Link not fitted
1 = Link fitted
D2:
VME_BOOT_MODE (reflects the status of user link E4). This bit is read-only.
0 = Link not fitted
1 = Link fitted
D3:
BOOT_RECOVERY (reflects the status of user link E7). This bit is read-only.
0 = Link not fitted
1 = Link fitted
D4:
Reserved reads ‘0’
D5: SELECT_ALTERNATE
D6: FLASH_CONTROL_WRITTEN
0 = Register not written
1 = Register written
D7: SELECT_RECOVERY
SELECT_ALTERNATE
SELECT_RECOVERY
A
REA
S
ELECTED
0
0
Main
0
1
Recovery
1
0
Alternate
1
1
Extended
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