Intelligent Automotive Ignition System

Electronic ignition is nothing new. Many “electronic”
ignition systems still rely on mechanical properties of
the distributor for RPM sensitive modifications
(advance/retard) and for actual spark “distribution”.
The proposed system uses a PIC12C508 for total
spark control on a 4-cylinder engine. This system could
be adapted to 6 and 8-cylinder engines by using a
“double-fire” (firing on power and exhaust strokes).
In this system, each cylinder has its own high voltage
coil, allowing a “hotter” spark than is supplied through
the arcing and inaccuracies of a mechanical distributor.
The PICmicro could use either a single or dual sensor
(IR) reading from a “code-wheel”. The dual system
would indicate top dead center of cylinder #1 (or some
other relevant timing mark) and single marks for each
cylinder. The single sensor system would only require
the TDC detector.
The PICmicro would time TDC detections, thereby
determining engine RPM. This RPM would be used in
a lookup table to determine the spark timing (single
sensor) or cylinder detect (dual). Each cylinder would
fire at the appropriate time.
System Benefits:
(over a mechanical design)
Inexpensive processing power means system can be
easily tuned for performance/emissions or other criteria.
Stronger, more accurate spark can be delivered.
No parts to wear, arc, or corrode.

Free Flight Model Aircraft Dethermalizing Timer

This application is for a Free Flight Dethermalizing
Timer for Model Aircraft. This is usually a mechanical or
fuse timer which spoils the lift of a model aircraft after 5
minutes. This is to prevent losing the aircraft in a strong
atmospheric thermal.
Using a bicolor LED and pushbuttons, a delay time of
between two and seven minutes in 10 second increments
is indicated B1 places the device in program mode and the LED
shows green. B2 then enters the number of 10 second
intervals with the LED flashing red for each interval in
groups of 5 for ease of reading. After the interval is
loaded, the timer is armed by pressing B2 again. When
armed the LED goes red. To start the timer, B2 is
pressed and held. The timer starts on release of B2.
When the unit times out, the 2N2222 is turned on, the
wire heats and contacts, and the control surface is
actuated and the 2N2222 is deactivated.
Nictol wire is a shape memory nickel titanium alloy
which contracts 3.5% of its length when heated. Nictol
wire also has a high resistance similar to nichrome
wire. Using 6-10 mil wire, 200 mA will heat the wire to
its activation temperature.

Digital PCM Radio Transmitter

The PICmicro™ can be used in a pulse coded radio
transmitter. The PICmicro’s crystal oscillator serves as
the RF source. “On” pulses are generated by running in
a timing loop. “Off” pulses can be generated by sleeping
with the WDT running. The WDT prescaler can be
changed dynamically to generate variable width “Off”
An I/O pin can turn off an optional final and/or multiplier.
The transmitted code can be fixed or encoded data
from I/O pins.The PICmicro’s oscillator serves to bias the final at
VDD/2. The 120W
resistor then sets the current in the
final. The tank can match the crystal or be an odd multiply.

Switch Interface/ Motor Controller for Auto Drivers Power Window Control

This idea is for the automotive industry. It serves as a
switch interface / motor controller for the driver’s side
power window control.
Using a PIC12C508 and an external comparator, one
could monitor the switches and control the motor necessary
for the operation of the driver’s power window.
Three switch inputs are required: 1) UP, 2) DOWN,
3) EXPRESS. Two outputs are required: drive_down
and drive_up. One interrupt or exception input is
required:Q rotor_stalled. Very simply:
if up,
then drive;
if down,
then drive_down;
if express,
then drive_down till not_stalled.

Automatic Volume Control That Will Work With Any TV/Remote

The device would consist of a microphone connected
to a PIC12C67X. The user presses a learn button
which sets the volume level. As the volume changes,
the microphone senses the volume and feeds it into the
A/D port of the PICmicro™. The PICmicro™ sends an
infrared signal (similar to a remote) to the TV to raise or
lower the volume.
In learn mode, the PICmicro™ reads the microphone
level and stores it as the reference level. As it monitors
the volume, it compares the volume to the reference
level and adjusts accordingly. This ensures minimal
background noise


Water Level Sensor for Bathtub, Jaccuzi, or Pool


The system monitors the water level using a
PIC12C67X. As water flows into the tub, the sensor
monitors the level. When the water reaches a predetermined
level the PICmicro shuts off the flow with a valve.
After the water is drained, the PICmicro™ resets the
valve for the next use. When it shuts off, the system
sounds an alarm. Also, a temperature sensor is incorporated
to prevent scalding

IR Car Detector for Changing Lanes

An IR coded signal is transmitted at the rear of a moving
car. At the same time an IR input is checked for the
same coded signal as just sent out. If the same signal
is found, then there is a car in the driver’s blind spot and
an LED is illuminated near the mirror. This system
would need to be implemented on both sides of the car.
The transmitter and receiver section need to be
shielded from each other.
1 PIC12C508
1 IR Receiver
1 IR Transmitter

Infra Red Cordless Mouse

Can anybody imagine that this little wonder,
PIC12C509, be used to control a cordless mouse?
Incredible! Just a handful of components, that's all! In
fact the circuit is small enough and perfectly suitable to
be fitted in the mouse housing with batteries. Current
consumption is minimized by the power reducing
SLEEP mode of the chip.
The circuit consists of two parts. A transmitter, which is
enclosed in the mouse, and the receiver, connected to
the PC via RS 232 link.
The PIC12C509 forms the heart of the circuit. Thanks
to the PIC12C509, it's use greatly simplifies hardware
design and the software. It senses the mouse movements,
mouse buttons and transmits the information to
the PC through infra red light emitting diodes (IR
LED's). The internal oscillator of the PIC12C509
enables one to use all of the I/O pins. The power-on
reset feature of the PIC12C509 rules out any need for
external reset circuitry, thereby saving one precious I/O
pin. Out of six I/O pins, one pin is configured to be output,
while the rest of the five pins are used as inputs.
The output pin drives two IR LED's through a MOSFET
BS170. Note that the MOSFET and one IR LED can be
saved and current consumption reduced by driving the
IR LED directly through the PIC12C509 pin at the
expense of limiting the range.
Three input pins out of the five are interfaced to the
three mouse buttons. Of course, two mouse buttons
can be used if desired. Flexibility of the design is evident.
Thanks to the PIC12C509 again! The remaining
two input pins are movement sensing inputs. Optical
sensing is used, which consists of an opto coupler with
a toothed wheel in between the LED and the phototransistor.
There are two such wheels, one for horizontal
movement and another for the vertical movement.
The wheels are mechanically coupled to the mouse ball
so that they rotate and electrical pulses are generated
with mouse movement. PIC12C509 senses the pulses
and converts the information into the appropriate format,
to be transmitted to the receiver via IR LED's. The
information, in the form of pulses, is then fed to the IR
LED through the driving MOSFET BS170. Thus the
information gets transformed into infra red light which is
transmitted to the receiver. When the microcontroller
transmits the motion information it produces exactly the
same pulses as would be produced by a regular
This is also a very simple circuit consisting of an IR
receiver, SFH505A, for instance and an op-amp
CA3140. The IR receiver receives the IR pulses and
transfers them into equivalent electrical pulses. The opamp
acts as an amplifier cum lavel shifter so as to make
these pulses compatible to RS 232 voltage levels. Note
that no extra power supply is needed for the receiver
circuit as it derives the power from the serial port itself.
Since this arrangement appears as a regular mouse to
the PC, there is no need to write device driver, and the
mouse can be used with the existing driver. Just plug
and play!