Z86D990 Datasheet, PDF (76/102 Pages) Zilog, Inc. – Low-Voltage Micro controllers with ADC

Z86D990/Z86D991 OTP and Z86L99X ROM
Low-Voltage Microcontrollers with ADC
69
A bit set to 1 in the P2M Register configures the corresponding bit in Port 2 as an
input, while a bit set to 0 configures an output line.
Port 4 Control and Mode Registers (P4 and P4M)
Port 4 is a general-purpose 8-bit, bidirectional I/O port, as shown in Table 28.
Each of the eight Port 4 I/O lines can be independently programmed as either
input or output using the Port 4 Mode Register (see Table 29.)
Table 28. P4 Register [Group/Bank 00h, Register 4 (R4)]
Bit
7
6
5
Bit/Field Port 4 Data
R/W
R/W R/W R/W
Reset
X
X
X
R = Read, W = Write, X = Indeterminate
Bit
Position Bit/Field
R/W
76543210 Port 4 Data
R/W
4
R/W
X
Value
Data
3
2
1
0
R/W R/W R/W R/W
X
X
X
X
Description
Port 4 Input/Output Register
.
Table 29. P4M Register (Group/Bank 0Fh, Register 2)
Bit
7
6
5
Bit/Field P47M P46M P45M
R/W
R/W R/W R/W
Reset
1
1
1
R = Read, W = Write, X = Indeterminate
Bit
Position Bit/Field
R/W
7654_210 Port 4 Mode
R/W
(by bit)
Select
____3___ P43
R/W
Mode Select
4
P44M
R/W
1
Value
1
0
0
1
3
P43M
R/W
1
2
P42M
R/W
1
1
P41M
R/W
1
0
P40M
R/W
1
Description
Input
Output
Output
Tristate High Impedance (available
on Z86L990/L991 only)
A bit set to 1 in the P4M Register configures the corresponding bit in Port 4 as an
input, while a bit set to 0 configures an output line.
Note: P43, the controlled current output pad, cannot be configured as
an input. (P43 read = P43 out)
PS003807-1002
PRELIMINARY