z89136 ZiLOG Semiconductor, z89136 Datasheet - Page 36

• Manufacturer Part Number: z89136
• Description: Low-cost Dtad Controller
• Manufacturer: ZiLOG Semiconductor

FUNCTIONAL DESCRIPTION (Continued)
Z89135/136 (ROMless)
Low-Cost DTAD Controller
Port Configuration Register (PCON). The PCON regis-
ter configures the port individually; comparator output is
on Port 3. The PCON register is located in the Expanded
Register File at Bank F, location 00H (Figure 24).
Port 4 and 5 Configuration Register (P45CON). The
P45CON register configures Port 4 and Port 5, individual-
ly, to open-drain or push-pull active. This register is located
in the Expanded Register File at Bank F, location 06H
(Figure 25).
Port 4 Open-Drain (D0). Port 4 can be configured as an
open-drain by resetting this bit (D0 = 0) or configured as
1-36
Figure 25. Port 4 and 5 Configuration Register (F) 06H (Write Only)
Note: Reset condition is 11111110
PCON (F) %00
D7 D6 D5 D4 D3 D2
P45M (FH) 06H
(Write only)
D7 D6 D5 D4 D3
Figure 24. Port Configuration Register (PCON)
P R E L I M I N A R Y
D2 D1 D0
D1 D0
Comparator Output Port 3 (D0). Bit 0 controls the com-
parator use in Port 3. A 1 in this location brings the com-
parator outputs to P34 and P35, and a 0 releases the Port
to its standard I/O configuration.
push-pull active by setting this bit (D0 = 1). The default val-
ue is 1.
Port 5 Open-Drain (D4). Port 5 can be configured as an
open-drain by resetting this bit (D4 = 0) or configured as
push-pull active by setting this bit (D4 = 1). The default val-
ue is 1.
R Always "1"
W 0 P34,P37 Standard output
R Always "1"
W No effect
Port 4 Configuration Bit
No effect
Port 5 Configuration Bit
No effect
1 P34,P37 Comparator output
0 Open-Drain
1 Push-pull
0 Open-Drain
1 Push-pull
DS97TAD0300
Zilog