PIC Beginner - Infrared Receiver and IR Protocol

[lester]

The article is an extract from the book, EXPERIMENTING with the PICBASIC PRO COMPILER, written by Les Johnson.

The book is cuerrently out of publication, however we are considering publishing an online version as part of the new PIC BASIC portal that we are developing to support PIC BASIC Users.

[komoe01]

dhouston,
When I change code, old result 0 turn to 255. All the keys press are same.




Header Logic 0 Logic 1 Logic 1 logic 0

2400 600 600 600 1200 600 1200 600 600
x a b c d e f g h i j
+------------------------+ +------+ +--------------+ +--------------+ +------+
| | | | | | | | | |
| | | | | | | | | |
| | | | | | | | | |
---+ +------+ +------+ +------+ +------+ +------
x____________________________|_____________|______ _____________|___________________|_____________|
pulsin header 1st loop 2nd loop 3rd loop 4th loop

return width of length





-- code start -------------------------------

          
         pulsin irIn , 0 , Header       'Line 1
    
            for i =0 to 3
               pulsin irin, 0 , tmp       'line 3

               if tmp > 90 then                
                    body.0[i] = 1         'line 5 
               else
                    body.0[i] = 0         'line 7  
               endif
            next

-- end of code -------------------------------

I think pulsin work as follow:

1. pulsin is timeout when no rising edge was found. return width is zero.
2. pulsin is time out when rising edge was found and then until falling edge. return the width length.


so pulsin in code run like that:


Line 1 : pulsin start measure (x) to end edge (b). Width is (a) to (b) so Header = 2400 (space (x) to (a) is not count.

Loop 0 (1st loop)
Line 3 : pulsin start measure (b) to end edge (d). Width is (c) to (d) so tmp = 600 (space (b) to (c) is not count.
Line 5 and 7: see the width lenght (not space) and decided logic 0
Loop 1 (2nd loop)
Line 3 : pulsin start measure (d) to end edge (f). Width is (e) to (f) so tmp = 1200 (space (d) to (e) is not count.
Line 5 and 7: see the width lenght (not space) and decide logic 1
Loop 2 (3rd loop)
Line 3 : pulsin start measure (f) to end edge (h). Width is (g) to (h) so tmp = 1200 (space (f) to (g) is not count.
Line 5 and 7: see the width lenght (not space) and decide logic 1
Loop 3 (4th loop)
Line 3 : pulsin start measure (h) to end edge (j). Width is (i) to (j) so tmp = 600 (space (h) to (i) is not count.
Line 5 and 7: see the width lenght (not space) and decide logic 0

PULSIN can only measure the width length.

When this code is used for NEC Protocol, all pulse are equal depending upon if statement (Logic 0 or 1)
Because In NEC, logic 1 or 0 is determined by space length. How can I measure space with pulsin.

lester
Thanks.

I already read Les Johnson's article and "Section 6: Experimenting with Remote Control" of that book. I already tested it. All are ok. But it's Sony IR Protocol (Pulse Width Modulation) that quite different from NEC IR Protocol (Pulse Distance Modulation).
I admire you and dhouston when I found your join date.
I start and learn picbasic at last week of July of this year. I search and collect PIC books (picbasic, C and Assembly) and article. I found about 60 books and articles. But I cannot find enough explanation for a command. eg. I want to know pulsin in detail. How pulsin work? examples relating pulsin. Pulsin in "PicBasic Pro Manual" is general. Picbasic is best language for me although I've little experience with C Language.


Moe

[komoe01]

Sorry sample wave is broken.



If wave picture is not found, Please see it in attachment picture

Moe

[dhouston]

When I change code, old result 0 turn to 255. All the keys press are same.

It works fine for me. It's impossible for me to guess at what changes you have made to it. Try to test it using my code exactly as written. Once that works, try modifying it for your application, going step by step to isolate where the problem is being introduced.

The waves you've attached (including the second one) are not NEC IR protocol.

How are you sending the IR codes?

[komoe01]

dhouston

The wave image is a sample (part of the sony protocol).

Try to test it using my code exactly as written.

Ok. dhouston

But 12F629 pic is not available for me. Just a few PIC model can buy in my country. I have to use 16F84A or 16F628A. Beside I use IR, not RF.
I'm a beginner for pic so I've not familiar with DEBUG that used in your code.

So I write code to PIC than I see the result of LED signal and Computer program.

When I test it using your code exactly, what can I see the result from where? Can I use Infrared remote control? or I must built your transmitter to test receiver.

I think I must to change some code.

I do my best as you say!

Thanks.

Moe

[dhouston]

The code I posted above in this thread is for IR. If you study it you will see that the method is identical to Lester's.

I have one 12F629 sending the 32 bit codes and another receiving the codes. Instead of IR transmitter and receiver I have the transmitter PIC connected directly to the receiver PIC. I do not have an IR receiver handy. However, I've used the same basic code in devices which did have an IR receiver.

I quickly modified a simple test program written for other purposes to display the DEBUG output. See the attachment. You should see the same output ($50$AF$42$BD) every 15 secs) in whatever terminal program you are using.

As for DEBUG, read the manual - it's similar to SerOut and SerOut2.

You should be able to use my code merely by changing the GPIO.x pins to whatever RA.x pins you are using. I haven't used a 16F84A in ages so I'm not going to write the conversion for you.

[komoe01]

I changed pin assign.

The result is successfully done.

I test ten different kind of DVD Remote. Key positions are changed but all are work well.

Now I run my program for two different tasks using same key of two different remote (Sony and NEC Protocol).

** two ir protocol can use in same pic **

Adouston,
THANK YOU VERY MUCH for your kindly help.

I read NEC protocol and compare code.

Header is 9ms
- no header found, restart

If (stx<760) Then init

Space between header and body is 4.5ms
-wait space

While PortA.2=1:Wend

Each pulse is a 560µs long
A logical "1" takes 2.25ms to transmit (pulse 560µs + space )
a logical "0" is only half of that, being 1.125ms (pulse 560µs + space )

Please let me know:
1. How to calculate (pulse>100) is logic 1.
2. and PULSIN_MAX 1140 . why do you use 1140

I say again. Thanks.

Moe.

[dhouston]

Please let me know:
1. How to calculate (pulse>100) is logic 1.
2. and PULSIN_MAX 1140 . why do you use 1140

I normally use RF where pulses & spaces are slightly different. I did the conversions to IR quickly, from memory and doing the math in my head so both figures are a bit on the high side.

IR transmitters (i.e. remotes) that used the NEC chip actually used numbers of carrier cycles as the unit of time rather than absolute number of µS. They were also battery operated so there could be some variation due to voltage variations. It is recommended to allow ±20% although that's probably generous with more modern remotes (the protocol has been around for about 40 years).

120% of 900 = 1080 instead of 1140.

With this method we are only able to measure the spaces which can be 0.56mS or 1.125mS. We just want to determine whether it is one or the other. A figure about halfway between the two values should work so 85 might be better than the 100 I used.

The NEC protocol is used by many manufacturers and you will encounter some that do not adhere exactly to the values given in the NEC datasheet so you need to build in a little flexibility.

[tr6coug]

Lester, is there somewhere we can download the include files from the book? I'd like to use the Sony IR files in a project. Thanks!

The article is an extract from the book, EXPERIMENTING with the PICBASIC PRO COMPILER, written by Les Johnson.

The book is cuerrently out of publication, however we are considering publishing an online version as part of the new PIC BASIC portal that we are developing to support PIC BASIC Users.

[amenoera]

dears ,

i know its a very long time , but please am stick on this , can you post a full working code for pic16f84a to decode nec protocol .
many many thanks .