Hi all,

New person here looking for some help in deciding how to do this...

Im building a circuit and beleive I need a PIC to be able to complete it. I currently have part of the circuit which is doing what I want it to do, but need a second part.

The first part of my circuit detects DTMF tones and provides a logic (+5V) output on one of its 4 outputs, depending on the DTMF tone detected. This works fine.

What I need to do is detect two sequencial tones and then provide a further output to a relay.

So, what I need the PIC to do is detect an input one one channel, then wait for another input on another channel, provided by the circuit I already have, both inputs have to be within a detemined amount of time or they should be discarded. Once the PIC have the two valid inputs (one after the other) it is then to provide a logic (+5V) output which will go on to a relay.

So my question is, which PIC should I choose to do this, what kind of programmer do I need? I can slightly familiar with programming (VB) but PIC´s are new to me, so be gentle!!

Any help on where to start would be a huge help.

Thanks in advance.

If I need to provide further info, please let me know and I will try and describe better.

 

You might be able to use sequential logic (state machine) to do this. But regarding PICs you have a pretty wide selection of PICS, you can propably use a really chip 8-16 bit PIC. But then you're gonna need a programmer. I would recommend PICKIT 2 from microchip. I've used that programmer and it has served me well. It's a ICSP so you can program the PIC while it's on the circuit board assuming you've designed the board for ICSP.

ICSP is "in circuit serial programming" in case you didnt know.
You are going to have to learn C or assembly to program the PICS.
MPLAB software that comes with PICKIT 2 has a decent C compiler for programming PICS. It also has an assembler if you want to do it in assembly. I recommend C though since assembly can be tedious.

 

Hi, thank you both for your info, it is much appreciated.

Alberto, I took a look at melabs, but do not notice the free version, did you mean download the demo? But this is limited to 31 lines, from what I read.

I will take a better look at this over the weekend.

Thanks again for your help so far, im sure i will be back for more!

Alberto, are you the same person I noticed in a different post that has designed the SMS I/O device with a GSM module? Is the source available for this or not? It is very similar to another project I am looking at. Thanks.

 

I recommend C though since assembly can be tedious.

Assembly may be tedious but it feels so good.

There's nothing like machine level to make a man feel like he's on top of the world.

 

hehe true that. But for a newbie in PICS assembly might not be the optimal approach

 

hehe true that. But for a newbie in PICS assembly might not be the optimal approach

Actually, I feel that assembly should be taught first if you're going from the bottom up (electronics to programming) but if you're learning from the top down (programming to electronics) then you sir, are absolutely correct.

Assembly is stupid easier to understand if you've learned basic digital logic circuits, and you carry the learning on as opposed to starting over with a higher language.