Z86L972 Datasheet, PDF (67/91 Pages) Zilog, Inc. – Low-Voltage Microcontrollers

Z86L972/Z86L973/Z86L974
Low-Voltage Microcontrollers
60
Table 22. P456CON Register (Group/Bank 0Fh, Register 0)
Bit
7
6
5
4
3
2
1
0
Bit/Field Not Used
P51_ P52_
P6_
P5_
P4_
Mode Mode Reserved Output Output Output
R/W
R/W R/W R/W R/W R/W
W
W
W
Reset
0
0
0
0
0
1
1
1^†
R = Read, W = Write, X = Indeterminate
Bit
Position
Bit/Field
R/W Value Description
76______ Not Used
R/W
These bits exist but do not have any
function assigned to them; they are
reserved for future extensions and must
not be used.
__5_____ Comparator 1 R/W 1
Mode
0
Analog (P50, P51 as Inputs)
Digital inputs
___4____ Comparator 2 R/W 1
Mode
0
Analog comparator inputs (P52, P53
configured as Inputs)
Digital inputs
____3___ Reserved
_____2__ Port 6 Output W 1
Configuration
0
Push-Pull Active
Open Drain Outputs
Always reads back 1*
______1_ Port 5 Output W 1
Configuration
0
Push-Pull Active
Open Drain Outputs
Always reads back 1*
_______0 Port 4 Output W 1
Configuration
0
Push-Pull Active
Open Drain Outputs
Always reads back 1*^†
Note: *Do not use the read-modify-write instructions (for example, OR and AND) with this register.
Bits 0, 1, and 2 always read back 1.
Note: ^†P43 can never be configured as push-pull. After any reset, P43 is configured as tristate high
impedance.
Port 2 outputs are configured using the P3M Register, shown in Table 23. Bit 0 of
the P3M Register switches Port 2 from push/pull active to open drain outputs. No
other bits in this register are implemented.
PS010504-1002
PRELIMINARY