– programmable duty factor for each pulse
– programmable number of pulses
• One output line from the Hardware Modulator to control
the driver transistor for the infrared LED (IR-LED).
Capable of sinking 27 mA at V
• Watchdog Timer to keep the transmitter from being
locked or malfunction
• Available packages: SO and DIP types (SO20, SO24,
SO28, SDIP24 and DIP20); see Chapter 4
• On-chip oscillator: 455 kHz to 6 MHz
• Single supply voltage: 2.0 V to 5.5 V
• Operating temperature: −20 to +50 °C.
2GENERAL DESCRIPTION
The PCA84C122 is a stand-alone microcontroller
designed for use in remote control transmitters for a wide
range of applications.
The PCA84C122 provides a number of dedicated
hardware functions for remote controller applications.
These functions include the following additional blocks to
the 84CXXX core:
• Interrupt Gate
• Hardware Modulator
• Output Driver
• Watchdog Timer.
= 2.0 V, V
DD
OUT
= 1.0 V
PCA84C122; 222; 422; 622; 822
Although the PCA84C122 is specifically referred to
throughout this data sheet, the information applies to all
the devices. The differences between the PCA84C122
and the other devices are specified in Chapter 3.
Figure 2 shows the general block diagram of the device.
The 84CXXX core plus 8 kbytes ROM and 64 bytes RAM
has the same function as described in the PCF84CXXX
family description (see
When the transmitter is not in use the microcontroller is in
Stop mode and the oscillator is halted. The AND gate
connected to the Port 1 (P10 to P17) lines provides the
wake-up to end the Stop mode.
The Hardware Modulator produces pulse bursts according
to the required protocol. The ON-time and OFF-time of
each pulse (i.e. duty factor) and the number of pulses are
controlled by software.
The Watchdog Timer (WDT) will reset the PCA84C122
when it has not been reloaded (reset) in time, because the
program has run out of sequence (endless loop,
continuous Idle mode, etc.). During Stop mode the
oscillator is halted, therefore the Watchdog Timer is not
running.
Automatic system reset is generated by the WDT if the
timer is not reset before overflow from counting within
a certain period of time.
The Output Driver can handle sufficient current to drive a
single transistor, that provides the required current for the
IR-LED.
2.1Important note
This data sheet details the specific properties of the
PCA84C122; PCA84C222; PCA84C422; PCA84C622
and PCA84C822. The shared characteristics of the family
of microcontrollers are described in the PCF84CXXXA
Family single-chip 8-bit Microcontroller of
IC14”
, which should be read in conjunction with this data
sheet.
“Data Handbook IC14”
).
“Data Handbook
1995 May 013
Philips SemiconductorsProduct specification
8-bit microcontrollers for
remote control transmitters
6.2Pin description
Table 1 Pin description for PCA84CX22AP, PCA84CX22AT, PCA84CX22BP, PCA84CX22BT and PCA84CX22CT
PIN
SYMBOL
P00 to P07 3, 2, 23, 22,
P10 to P17 19, 18, 17, 16,
P20 to P23 −14, 15, 1, 28−−standard I/O Port lines, generally
INT4538test T0 and external interrupt input
T0/
T15649test T1 input
RESET67510active HIGH reset;
SDIP24/SO24
(see Fig.3)
10, 11, 14, 15
1, 22, 12, 13
SO28
(see Fig.4)
4, 3, 26, 25,
11, 12, 17, 18
22, 21, 20,19,
2, 27, 13, 16
SO20
(see Fig.5)
2, 1, 20, 19, 9,
10, 11, 12
16, 15, 14, 131, 20,19, 18standard I/O Port lines, generally
DIP20
(see Fig.6)
7, 6, 5, 4, 14,
15, 16, 17
standard I/O Port lines, generally
used for keypad scanning
used for keypad sensing
used for visible LED’s
normally connected to V
For further information see
PCF84CXXXA description in
“Data Handbook IC14”
XTAL1910813crystal or ceramic resonator
XTAL289712
OUT2124183pulse train output pin, capable of
sinking 27 mA
V
DD
V
SS
78611power supply
2023172ground
DESCRIPTION
.
SS
.
7POWER-ON-RESET STATUS AND PORT OPTIONS
• All Port lines are standard I/O (option 1).
• RESET (Power-on-reset) level of 1.3 V.
After Power-on-reset, Port 0 is reset to LOW; Port 1, Port 2 and
1995 May 017
OUT are reset to HIGH.
Philips SemiconductorsProduct specification
8-bit microcontrollers for
remote control transmitters
8HARDWARE MODULATOR
The Hardware Modulator is the main derivative part in the
PCA84C122. Figure 7 shows the internal architecture.
The Hardware Modulator generates a pulse train whereby
the ON-time of a pulse and the OFF-time between pulses
can be programmed in a number of clock cycles
(period = 1/f
); see Figs 8 and 7.
osc
internal bus (IB0 – 7)
ON-TIME
REGISTER
(8)
OFF-TIME
REGISTER
(8)
PCA84C122; 222; 422; 622; 822
The number of pulses of the train is also programmable.
The time between pulse bursts is determined by software,
possibly using the standard 8-bit Timer/Counter.
8.1Interface between the 84CXXX core and
derivative logic
There are three (derivative) registers and one (derivative)
counter that must be loaded from the core.