Triggering 555 Timer: How to Use PIC Microprocessor

In summary, the person is having trouble figuring out how to trigger a siren using an astable circuit with a monostable 555 and a PIC microprocessor. Their teammate says it can't be done, but the person has found a way to make it work by grounding the trigger pin. They are wondering if there is a chip or circuit they can add to allow the PIC to send a signal to ground the trigger pin. Suggestions are given, such as checking power supply compatibility and using an oscilloscope to check for a pulse on the PIC output pin. If all else fails, they may need to replace the PIC and 555 or have someone check their wiring against the schematic.
  • #1
djkross
1
0
hey guys... I'm having some trouble trying to figure out how to trigger a siren I'm working on. i have an astable circuit setup with the output of the monostable 555 connected to the output of the astable 555s to trigger the circuit. i wanted to trigger the circuit using a PIC microprocessor but a teammate of mine says i can't do that. so far, the only way it's actually working is by grounding the trigger pin of the monostable 555. is there a chip or a circuit that i could add to this existing one that will be connected to the trigger pin of the monostable 555 and could have a signal sent to it by the PIC that will ground its output and thereby grounding the trigger pin of the monostable 555, which will get the result that I'm looking for?
 
Engineering news on Phys.org
  • #3
I checked the data sheets for the PIC16F84A and the Texas Instruments LM555 and don't see a problem.

If the I/O port of the PIC is set as an Output and the supply voltages are compatible, I see no reason it wouldn't work. Ideally the PIC and the 555 Monostable should be driven with the same power supply, +5V and Gnd.

Be sure there are power supply bypass capacitors installed fairly near the chips.

Make sure your program sets the PIC output pin you are using to be Output, not Input. The Trigger pulse from the PIC to the Monostable should be normally high with a low pulse at least 1uS duration, perhaps longer if you are using a CMOS version of the 555. Since the PIC can operate with a 20MHz clock, you program will probably need a time delay to set the pulse duration

The Trigger pulse should also be shorter than the 555 output pulse.

If you have an Oscilloscope available, check for a pulse on the PIC output pin.

If all that fails to fix it, have someone else check your wiring against the schematic. Next would be to either replace the PIC and 555 or try them in another working circuit to see if they are still good.
 
  • Informative
Likes anorlunda

1. What is a 555 timer?

A 555 timer is a type of integrated circuit (IC) that is commonly used in electronic devices to generate precise and accurate time delays, oscillations, and pulses.

2. How does a 555 timer work?

A 555 timer works by using a combination of resistors, capacitors, and transistors to create an astable or monostable multivibrator circuit. This circuit produces a square wave output with a specific frequency and duty cycle based on the values of the external components.

3. How can I use a 555 timer with a PIC microprocessor?

To use a 555 timer with a PIC microprocessor, you will need to connect the output of the 555 timer to one of the input pins of the PIC. You can then program the PIC to receive and interpret the signals from the 555 timer and use them to trigger other actions or events.

4. What are some common applications of a 555 timer?

A 555 timer can be used in a variety of applications, including timers, pulse generation, oscillator circuits, LED and light control, and motor control. It is also commonly used in electronic toys, security systems, and other electronic devices.

5. Is there a specific programming language or software required to use a 555 timer with a PIC microprocessor?

Yes, you will need to use a programming language such as C or assembly to write the code for the PIC microprocessor and control the 555 timer. You will also need a software tool, such as MPLAB, to compile and upload the code to the microprocessor.

Similar threads

  • Electrical Engineering
Replies
30
Views
4K
  • Electrical Engineering
Replies
9
Views
2K
  • Electrical Engineering
2
Replies
58
Views
9K
Replies
16
Views
2K
Replies
2
Views
3K
  • Electrical Engineering
Replies
9
Views
3K
  • Electrical Engineering
Replies
29
Views
9K
  • Electrical Engineering
2
Replies
49
Views
2K
  • Electrical Engineering
Replies
8
Views
7K
  • Electrical Engineering
Replies
11
Views
2K
Back
Top