Quad encoder problems

[SteveB]

Smitty,
Try this on your cmd line:

pbpw -p16f628 -ampasmwin yourfilename

The trouble is actually two fold.
1) PBP is DOS based, and does not like long file names. PBPW is ok with them.
2) You need to use the MPASM assembler. So make sure it is installed before you run the above line! It is needed for the Macros, as well as if you make the switch to the 18F series.

Out of curiosity, why not use MicroCode Studio?

Good Night,
Steve B

EDIT: Use the name for your file on the above cmd line

[sayzer]

Smitty,
.....
Out of curiosity, why not use MicroCode Studio?
.....

Hi Smitty,

As Steve B also asks about it here, is there a particular reason why you are not using MicroCode Studio?

Also, for the encoder , don't you think that you can do what you need with one direction?

If you think you can, then I can give you some piece of code for TMR1 and TMR0 so that you can set it up for reading the encoder, and suggest some ways of having the missing counts minimized.

In your case, as much as I understood it, the degrees needed are wide enough to cover the missing counts.

[smitty505000]

I just tried microcode studio and get the same errors. Cant find 16F628.inc

This file is in the pbp directory, I do not understand.

sayzer, Thanks for the offer but I do need both directions to be able to tell if it is a right or left roll ,an up or down pitch and how far for both.

Microcode studio is pretty sweet I must say. Thanks for recommending it.

Smitty

[SteveB]

You did restart your computer, right? Well, if we don't have any success going that route, there are alternatives.

Look at the code in the Interrupt Handler. Put this in your main loop, so it repeatedly checks PORTB for changes. Like This:

'************************
'  DEFINE your OSC 
'  and any other
'  configuation items
'************************


Old_Bits       VAR BYTE
New_Bits       VAR BYTE
RotEnc1_val    VAR BYTE  'Connected to PORTB<4:5>
RotEnc2_val    VAR BYTE  'Connected to PORTB<6:7>
TRISB = %11110000
RotEncDir      VAR BIT

'************************
' SETUP YOUR LCD HERE!!!
'************************

Old_Bits = PORTB & (%11110000)

Main:
     New_Bits = PORTB & (%11110000)
     IF (New_Bits & %00110000) = (Old_Bits & %00110000) then No_Change_Rot1
     RotEncDir = New_Bits.5 ^ Old_Bits.4
     if RotEncDir = 1 then
          RotEnc1_val = RotEnc1_val + 1
          if RotEnc1_val = 36 then RotEnc1_val = 0
     ELSE
          RotEnc1_val = RotEnc1_val - 1
          if RotEnc1_val = 255 then RotEnc1_val = 35
     ENDIF
No_Change_Rot1:
     IF (New_Bits & %11000000) = (Old_Bits & %11000000) then DoneRotEnc
     RotEncDir = New_Bits.7 ^ Old_Bits.6
     if RotEncDir = 1 then
          RotEnc2_val = RotEnc2_val + 1
          if RotEnc2_val = 36 then RotEnc2_val = 0
     ELSE
          RotEnc2_val = RotEnc2_val - 1
          if RotEnc2_val = 255 then RotEnc2_val = 35
     ENDIF
DoneRotEnc:
     Old_Bits = New_Bits
     
     LCDOUT $FE, 2,"ROT1:", DEC2 RotEnc1_val,"ROT2:", DEC2 RotEnc2_val
GOTO Main

Let's walk before we run and get this working.

Steve

[smitty505000]

Steve,
Yup, restarted pc many times. LOL. I would really like to know what the problem is. I guess I will have to look into it further.

You said "Look at the code in the Interrupt Handler. Put this in your main loop"

Did you mean to compile just the code you listed or to add it to one of the others? If you meant by itself then it compiled just fine.

I tried it out and had some strange readings. It starts with Rot1:00 and Rot2:35. When I rotate the encoders nothing happens.

To test and see if it was the encoder or the program, I unpluged the a & b chanels from encoder 1 and alternately touched them to ground and the numbers changed. This makes me think something is wrong in the encoder circuit. I played arround with different values on the resistors to no avail. The encoders output a positive voltage between ~1.85 and 5 and I have 4.7K resistors pulled to ground on each channel.

I did notice if I was under a bright light and held the encoders at just the right angle the numbers changed but they were jumping arround and not going 1.2.3.4~.

Man I didnt think encoders were so tough.

Smitty

[SteveB]

Smitty,

You said "Look at the code in the Interrupt Handler. Put this in your main loop"

Did you mean to compile just the code you listed or to add it to one of the others? If you meant by itself then it compiled just fine.

Just use the "new code" in the last post by itself (I did the moving for you).

It starts with Rot1:00 and Rot2:35

Add something like this just below the variable declarations to give an initial starting value.

RotEnc1_val = 0
RotEnc2_val = 0


OK. Do you have the datasheet for the encoders? I assumed (always bad) that they where mechanical encoders, similar to the one shown here. Hook-up as per the nice diagram.

If they are not mechanical encoders, then they are optical. If so, they will have a Vcc, GND, ChA, and ChB. Also, no pull-ups (or downs) required.

At least it looks like the code is working. More info please.

Steve

[smitty505000]

Ok, I did just use the code by itself and I understand setting the variables to =0. Off to a good start

The encoders are optical with no data sheet since I pulled them out of a ball mouse. There is an emitter, wheel with 36 slots, and reciever for each encoder. They are in the same mounting positions as when the mouse was a mouse. I just chopped off the pc board behind them and attached my wires. The emitters only have 2 pins, +5v and ground. The recievers have 3 pins, A,B, & +5v. I know this because I traced them back on the mouse board before cutting. I also checked another mouse to be sure. (I bought 4 of them to play with).

With my original code (the really simple one a few posts back) nothing happened until I put in the resistors to ground. Thats the only reason they are in the circuit. The read out on the lcd also displayed channel A and B status and I could see 00 01 11 10 00 when rotated very slowly.

I did try your code without the resistors and it didnt make any difference.

I agree with you when you say we need to walk before we run. So I checked the outputs of the encoders with a logic probe. I am getting a high/low pulse out of each of the channels when they are rotated.

Smitty

[SteveB]

So I checked the outputs of the encoders with a logic probe. I am getting a high/low pulse out of each of the channels when they are rotated.

What voltage do they output on the channels? I haven't hacked any mouse encoders, so a google on that (or someone else on this forum who has could chime in) could help make sure the hardware portion is working properly.

I do know the code is working now. I scared up 2 mech encoders, and hooked them up to an 18F4620 I have. Using the internal pull-ups on port B, worked without a hitch. I see no reason it wouldn't work on the 16F628.

Steve

[mister_e]

The encoders output a positive voltage between ~1.85 and 5 and I have 4.7K resistors pulled to ground on each channel.

So it's never 0V? @1.85 you're probably sometimes in-between Low and High logic Level. You may need to 'filter' it a little bit to avoid oddity.

1.Use the internal voltage comparator, set the threshold and use their interrupt to increment the counter.
OR
2.try something like...
<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=1067&stc=1&d=115794620 6">
maybe one diode could be enough... maybe not
HTH

[smitty505000]

I got it working! Sort of. I played arround with different value resistors and some diodes as sugested by mister_e and ended up with 30K resistors. Also seams my pic16f628-20p dosnt have a very accurate osc in it. I hooked up an external resonator and it works at 20mhz using Steve's slightly modified code from post #12. Thanks Steve!
The only thing now is it sometimes skips or looses count. Either the pic running at 20mhz cant keep up or the infrared red rx cant keep up. These encoders came out of a PS2 computer mouse. The ones that turn off the ball.

Any ideas guys?

Thanks!
Smitty

[SteveB]

I got it working! Sort of. I played arround with different value resistors and some diodes as sugested by mister_e and ended up with 30K resistors. Also seams my pic16f628-20p dosnt have a very accurate osc in it. I hooked up an external resonator and it works at 20mhz using Steve's slightly modified code from post #12. Thanks Steve!
The only thing now is it sometimes skips or looses count. Either the pic running at 20mhz cant keep up or the infrared red rx cant keep up. These encoders came out of a PS2 computer mouse. The ones that turn off the ball.

Any ideas guys?

Thanks!
Smitty

Now your walking, time to RUN!! Go back to post #6 and give the interrupts a try. With the optical encoders and interrupts, you should have not any switch bounce, and you should also not have any "skips". Well, if it turns faster than the interrupts can process the inputs, you can have some skips, but the nice thing about the interrupts is that the updates to the rotarty encoders count will not "wait" on the LCD output to finish.

Give it a shot,
Steve