
2001 Apr 17
75
Philips Semiconductors
Product specification
Digital telephone answering machine chip
PCD6001
16.2.3
P
ORT
4 R
EGISTER
(P4)
The alternative outputs (GPC, FSO, FSK and LE) are connected with the general purpose outputs via an AND gate.
Therefore, when using the alternative functions the corresponding port bits should be set to a logic 1.
Table 73
Port 4 Register (SFR address 98H); bit addressable; reset state 1EHH; note 1
16.2.4
P
ORT
4 C
ONFIGURATION
R
EGISTER
(P4CFG)
This register is used to select the output configuration of the pins WR, RD and P4.0 to P4.4. The output configuration is
open-drain by default after reset. Note that the output configuration of P4.5 is selected by the P4.5 bit in SFR ALTP.
Table 74
Port 4 Configuration Register (SFR address 9FH); reset state 00H
Table 75
Description of P4CFG bits
16.2.5
A
LTERNATIVE
P
ORT
F
UNCTION
R
EGISTER
(ALTP)
This register selects the pin configuration for the MSK, IOM master/slave and general purpose function; see Table 77.
The general purpose clock function is described in Section 9.1. The LE functionality is described in Section 10.13.
Table 76
Alternative Port Function Register (SFR address ABH); reset state 00H
Table 77
P3.7, P3.6, P3.1 and P3.0 selection of pin configurations for alternative function
7
6
5
4
3
2
1
0
P4.5/GPC
P4.4/FSI
P4.3
P4.2/FSO
P4.1/FSK
P4.0/LE
7
6
5
4
3
2
1
0
WR
RD
EAM
P4.4
P4.3
P4.2
P4.1
P4.0
BIT
SYMBOL
DESCRIPTION
7
6
5
WR
RD
EAM
If WR = 0, then open-drain configuration. If WR = 1, then push-pull configuration.
If RD = 0, then open-drain configuration. If RD = 1, then push-pull configuration.
The EAM bit is used to select the Enhanced Addressing Mode; this is described in more
detail in Chapter 12.
If P4.4 = 0, then open-drain configuration. If P4.4 = 1, then push-pull configuration.
If P4.3 = 0, then open-drain configuration. If P4.3 = 1, then push-pull configuration.
If P4.2 = 0, then open-drain configuration. If P4.2 = 1, then push-pull configuration.
If P4.1 = 0, then open-drain configuration. If P4.1 = 1, then push-pull configuration.
If P4.0 = 0, then open-drain configuration. If P4.0 = 1, then push-pull configuration.
4
3
2
1
0
P4.4
P4.3
P4.2
P4.1
P4.0
7
6
5
4
3
2
1
0
IOM on P3
IOM master/
MSK
P4.5
GPC off/on
GPC source
LE off/on
early LE
ALTP.6
ALTP.5
MODE
0
0
1
1
0
1
0
1
general purpose I/O port
MSK
IOM slave
IOM master