DTMF and PIC for Remote Control

[doggitz]

Recently started playing with PICs and am just fascinated at what they can do.

I am trying to build a simple remote control system for an amateur radio remote receiver using a DTMF decoder chip like an 8870 and a PIC such as a 16F877A. Does anyone have a code example of how the PIC would handle the input lines from the DTMF decoder? There is a valid digit line and 4 "decode" lines from the decoder. All I need is the BASICPRO program which would strobe the input lines, and when the valid signal is received determine which digit it represents. I can write the code for passwords, and determining what function the received number is to execute. I have looked through the code example part of the site and found one for a matrix keypad, but it does not include the use of a "valid" signal line.

There is at least one example on the web, but it is written in assembly language and I got too discouraged trying to "decode" it.

Thanx

[Darrel Taylor]

There's an example for the LAB-XT Telephony Experimenter Board (MT8870) on the meLabs samples page.

http://melabs.com/resources/samples.htm#xtpbp

grabrxt.bas
<br>

[mike1939]

Hello Doggitz
I am just starting out on a DTMF for remote control via telephone.
I am using 8870 DTMF receiver and PIC 16F628 to do the work.
So far DTMF receiver works fine but as usual the software is slowing me down. I want to be able to enter a PIN code..>...then a Function code...>.. the the Action code. Stuck on first part, even using PBP hasn't made things easier. I gave up on assembler ages ago..too tricky to get right.
If you have any shortcut ideas or pointers from your work I would be most appreciative.
Rgds
Mike
12/2/2010

[Dave]

doggitz, Attached is a first cut program I wrote about 8 years ago for our repeater system. It is one of the first programs I wrote using PBP so don't laugh....It is a remote link control program that worked the first time.... I used a simillar tt decoder to the 8870. I hope this will help you get a start.

Dave Purola,
N8NTA

[ScaleRobotics]

Recently started playing with PICs and am just fascinated at what they can do.

I am trying to build a simple remote control system for an amateur radio remote receiver using a DTMF decoder chip like an 8870 and a PIC such as a 16F877A.

PICs are pretty amazing. Here is an application note from Microchip on using PIC18 devices to decode DTMF without a decoder chip. I still recommend the 8870, but thought you would be interested to know that it can.

http://ww1.microchip.com/downloads/e...TMFDetv1.2.zip

[mike1939]

Why doesn't
pincode1 = PORTB && $0F...work in PBP ?

When PORTB lower 4 bits are 0010 && 00001111 I should get 0010
I get $9C...????
How weird?

Bob, from across the road, has gone on his final mission.
Mike1939

[Bruce]

It doesn't work because you're using a logical operator instead of the bitwise operator.

pincode1 = (PORTB & $0F) would return the right value.

Logical operators can only return true or false.

[mike1939]

I have new coding problem, using TMR0 I do not understand........put simply

loop1:
  if intcon.2 = 0 then loop1  
  intcon.2 = 0
  clicks=clicks+1
  if clicks >=1900 then
  clicks=0
  high pin11:pause 100:low pin11  'Flash LED for 10th of second
  secs=secs+1
  endif
  if secs>=5 then 
  high pin10:pause 100:low pin10
  gosub nowt
  secs=0 'Reset secs
  endif
  goto loop1  
  end
  nowt: 
  return

But fails if 
              gosub nowt
              endif
              goto loop1  
              end
              nowt: 
              secs=0 'Reset secs
              return

The inclusion of any code in the sub-routine at nowt: causes whole to fail?

[mackrackit]

Can you post the whole code, using code tags, so we can see how everything is setup? TMRO is "normally" set to trigger an interrupt handler so I am not sure what you are doing with what I see posted.

Might just be running out of time???

[mackrackit]

Bob, from across the road, has gone on his final mission.

Bob who???

[mike1939]

Thank you, & NOT &&, well spotted. Progress is being made, I learn a new thing every day

Bob Pierson was a WW2 rear gunner in Lancasters, A "Tail End Charlie".
Sad loss for us here.

Mike

[mackrackit]

Me respects to Bob.
We owe so much to our Veterans.