Chas's Security Device Project

Howdee,

I have fabricated an alarm system. It is mounted on a soldered perfboard. For testing purposes, I am pinned from an empty ATTINY85 8-pin carrier which then goes to the arduino.
When the hardware and software is debugged, I'll use the ARDY AS ISP and upload the software to the Tiny.

I am supporting an Attiny85 handling inputs from a PIR (Passive InfraRed motion detector) With digital out to d10 in, an LDR (Light Dependent Resistor) with ANALOG OUT to A0 in, 21-white 12 v LEDS In a 7x3 configuration current limited by 7 resistors . The LEDs are fed by D9 out to a TIP20 Darlington transistor.

The arrangement is currently connected to an external 12v 2a PS(Power Supply), providing 12v to the LEDs on the VCC (+12v) and supplying ~+4.8v to the ATTINY85 8-pin carrier, the PIR, and LDR thru voltage dividing resistors.

The arduino connection is pinned to the empty ATTINY carrier for testing...hardware works fine...but...

software
1.sensing day/night light levels turning on/off the LEDs as appropriate, calling the following Fns
A. random 5-15 sec flash for day and and nite routines .
B. a movement detection Fn calling 1.a flash routine to the LEDs that continue to flash as long as the PIR outputs HIGH(~30 seconds for the PIR to settle down)

Last nite I added a little Piezo buzzer driven by the above routine calling a nasty ~ 8-9khz rise and fall which is loud as hell , driven by D4s PWM out.

I really like the addition of the "siren" rising and falling between LED flashes when the PIR detects movement.

I am now thinking of adding an audio amp driven by a microSD card, PLAYING something like "WARNING your picture is now on the internet! Leave or the GLOCK AIMING ROUTINE WILL BE INITIALIZED!" (JKing)

Ok, forget the SD card audio out ...for now...

The problem is, with the addition of the siren, I need another pwm port, and the AtTiny85 only has 2 digital pins, and the PIR needs one digital input. (D10). The LEDs are using the other(D9).
Now I know that theoretically, digital pins can be changed from output to input and back again thru an ad hoc pinmode() routine, but since the buzzer goes from Dout to gnd, sharing the line with PIR has electrically disrupted the PIR output line. I need an additional digital channel which the ARDY has but the AtTiny85 doesn't.... :-( ...

Question: can I take one of the AtTiny85 ADC channels and turn it into the additional Digital channel I need, as a DIGITAL OUTPUT for the Sireen???

Thanks beforehand for listening and your speedy responses, and thanks to the huge, smart as Hell Arduino community, especially MIT, and LAdyAda, SparkFun and Bliptronics forums.

Chas


Thanks,and have a wonderful day!

Chas (Ipd)

Be bigger than yourself!

Keep your eyes on the stars, Your feet on the ground...

Sending healing vibes your way!
~~~~~~~~~~~~~~~~~~~~~~~~~~

Please visit www.katrinasangels.org

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