9
Philips Semiconductors Product specification
TELX microcontrollers for CT0
handset/basestation applications
P8xCL883; P8xCL884
Note
1. Where: X = undefined state or not implemented bit.
6.2 I/O facilities
6.2.1 PORTS
The P8xCL883/P8xCL884 have 19 and 18 I/O lines
respectively, treated as 19 and 18 individually addressable
bits or as three parallel 8-bit addressable ports.
The alternative functions are detailed below:
Port 0 Offers no alternative functions.
Port 1 Used for a number of special functions:
• P1.0 to P1.7 provides the inputs for the external
interrupts INT2 to INT9
• P1.2/T2COMP for external activation and
Compare/Auto-reload output function of Timer 2
• P1.4/CLK for the clock output
• P1.6/SCL and P1.7/SDA for the I
2
C-bus interface
are real open-drain outputs or high-impedance;
no other port configurations are available.
Port 2 Not available.
Port 3 Pins can be configured individually to provide:
• P3.0/RXD/data and P3.1/TXD/clock/MOUT0
which are serial port receiver input and
transmitter output (UART)
• P3.4/T0 as counter input; available only in
P8xCL883.
To enable a Port pin alternative function, the Port bit latch
in its SFR must contain a logic 1.
WDT
WDCON A5 1010 0101
WDTIM FF 0000 0000
OTP interface
OAH D5 X00X XXXX
OAL D4 XXXX XXXX
ODATA D6 XXXX XXXX
OISYS DC 000X 0000
OTEST D7 0000 0000
Reserved locations; do not write
reserved E7, FD −
REGISTER
ADDRESS
(HEX)
RESET VALUE
(1)
Each port consists of a latch (Special Function Registers
P0 to P3), an output driver and input buffer. All ports have
internal pull-ups. Figure 3b shows that the strong
transistor ‘p1’ is turned on for only one oscillator period
after a LOW-to-HIGH transition in the port latch. When on,
it turns on ‘p3’ (a weak pull-up) through the inverter IN1.
This inverter and transistor ‘p3’ form a latch which holds
the logic 1.
Port P1.3 has LED drive capability.
6.2.2 P
ORT I/O CONFIGURATION
I/O port output configurations are determined by the
settings in port configuration SFRs. There are 2 SFRs for
each port: PnCFGA and PnCFGB, where ‘n’ indicates the
specific port number (0 to 3). One bit in each of the 2 SFRs
relates to the output setting for the corresponding port pin,
allowing any combination of the 2 output types to be mixed
on those port pins. For example, the output type of P1.3, is
controlled by the setting of bit 3 in the SFRs P1CFGA and
P1CFGB.
The port pins may be individually configured via SFRs with
one of the following modes (P1.6 and P1.7 can be
open-drain or high-impedance but never have any diodes
against V
DD
). These modes are also shown in Fig.3.
Mode 0 Open-drain; quasi-bidirectional I/O with
n-channel open-drain output. Use as an output
requires the connection of an external pull-up
resistor; e.g. Port 0 for external memory
accesses (EA = 0) or access above the built-in
memory boundary. The ESD protection diodes
against V
DD
and V
SS
are still present; see Fig.3b.
Except for the I
2
C-bus pins P1.6 and P1.7, ports
which are configured as open-drain still have a
protection diode to V
DD
.
Mode 1 Standard port; quasi-bidirectional I/O with
pull-up. The strong pull-up ‘p1’ is turned on for
only two oscillator periods after a LOW-to-HIGH
transition in the port latch. After these two
oscillator periods the port is only weakly driven
through ‘p2’ and ‘very weakly’ driven through ‘p3’
(see Fig.3b).
Mode 2 High-impedance; this mode turns off all output
drivers on a port. Thus, the pin will not source or
sink current and may be used as an input-only pin
with no internal drivers for an external device to
overcome (see Fig.3c).
Mode 3 Push-pull; output with drive capability in both
polarities. Under this mode, pins can only be
used as outputs (see Fig.3d).