
Technical Data
MC68HC11E Family
—
Rev. 4
84
Operating Modes and On-Chip Memory
MOTOROLA
Operating Modes and On-Chip Memory
IRV(NE)
—
Internal Read Visibility (Not E) Bit
IRVNE can be written once in any mode. In expanded modes, IRVNE
determines whether IRV is on or off. In special test mode, IRVNE is
reset to 1. In all other modes, IRVNE is reset to 0. For the
MC68HC811E2, this bit is IRV and only controls the internal read
visibility function.
0 = No internal read visibility on external bus
1 = Data from internal reads is driven out the external data bus.
In single-chip modes this bit determines whether the E clock drives
out from the chip. For the MC68HC811E2, this bit has no meaning or
effect in single-chip and bootstrap modes.
0 = E is driven out from the chip.
1 = E pin is driven low. Refer to the following table.
PSEL[3:0]
—
Priority Select Bits
Refer to
Section 5. Resets and Interrupts
.
Mode
IRVNE Out
of Reset
E Clock Out
of Reset
IRV Out
of Reset
IRVNE
Affects Only
IRVNE Can
Be Written
Single chip
0
On
Off
E
Once
Expanded
0
On
Off
IRV
Once
Bootstrap
0
On
Off
E
Once
Special test
1
On
On
IRV
Once