PCA84C122 Datasheet, PDF (3/24 Pages) NXP Semiconductors – 8-bit microcontrollers for remote control transmitters

Philips Semiconductors
8-bit microcontrollers for
remote control transmitters
Product specification
PCA84C122; 222; 422; 622; 822
1 FEATURES
• 84CXXX CPU
• ROM, RAM and I/O configurations are device
dependent; see Chapter 3
• Two test inputs: T0 (ANDed with Port 1 input lines)
and T1
• 3 single-level vectored interrupt sources:
– external (T0/INT and Port 1, for keypad press
wake-up function)
– timer/counter (TI)
– hardware modulator interrupt
• 8-bit programmable timer/counter with 5-bit pre-scaler
• Power saving: Idle and Stop modes are provided
• Hardware Modulator providing pulse bursts, with:
– 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_DD = 2.0 V, V_OUT = 1.0 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.
2 GENERAL 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.
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 “Data Handbook IC14”).
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.
2.1 Important 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 “Data Handbook
IC14”, which should be read in conjunction with this data
sheet.
1995 May 01
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