555 timer attached to a passive infrared sensor

[nylamre]

i need help

my final year project requires a passive infrared sensor which can detect human motion. but i dont know how to build a circuit

the project must operate this way

there must be a timer which reset when it detects motion(the PIR is the one who detetects) but after 30 minutes that there is no motion, it will trigger a microcontroller. i wanna ask about how i can create a circuit out of it. please help thank you

 

[bigdogguru]

If you are going to incorporate a microcontroller (MCU) into your design, there is no need for a 555 timer. Most MCUs have one or more timer/counters which can be used to produce a delay.

Do you have a particular MCU you were considering for your design?

BigDog

 

[nylamre]

MCU AT89S51. until now i cant simulate my circuit. we need to present a working circuit as soon as possible. how can i build a circuit for my project? please help me

 

[bigdogguru]

You could use an external interrupt to start the timer in the AT89S51 to accomplish the task.

However, with such as simple task, you may want to attach the output of the PIR to one of the port pins and constant poll (check) the pin status.

When a change occurs you can the start one of the timers in the AT89S51 to implement the desired delay. Or with a delay of 30 minutes you may want to implement the delay in software.


Can you give me more of a details description of the various tasks and the desired flow of events?

Also have you ever used a timer in a 8051 devices? Any experience with general purpose digital I/O with the 8051?

BigDog

 

[nylamre]

this is my first project involving a microcontroller

the device must achieve the following:
my project works this way. it is a device that can detect motion (particularly human). then it can dessiminate a message that an operating appliance is left behind and then the appliance can be switch on or off through an sms message.

it features the following:
1. their is a sensor (i choose a PIR motion based sensor) which detects movements.
2. then my idea was to put a timer. this timer will reset everytime the sensor is active
3.and then after 30 minutes that the sensor is inactive, the microcontroller will send an sms message to a mobile phone( in this gsm module or any mobile that supports an AT commands)
4. can be switch on or off through a sms.

 

[bigdogguru]

Ok,

Because this is your first project involving the programming of microcontrollers, I would recommend attempting a very simple intro project, before moving on to your main project.

Try making a LED flash on/off at a steady rate. Attach the LED to one a general purpose digital I/O along with a current limiting resister.

Do this will accomplish several things, including, understanding how to compile a program and download it into your MCU, learn to properly configure the I/O port and how to generate a delay as well as many other things.

Attempt to accomplish this simple task first and report back your progress. Once you have accomplished it, you can then move onto your main project.

If you have any problems, post them here so that I can advise you.

BigDog

 

[nylamre]

hi bigdog
i just found out that AT89S51 is not available in our place. the only available are the PIC. could you suggest which PIC i should use with my project? do i need two pics working on my project?