Rotary Encoder

ericgibbs · Jan 31, 2014

hi
I see that you have placed the LCD's service call in the Idle loop, is this just temporary.?
You dont need to call the LCD until there has been an Interrupt, you could place a IntFlag in the ISR, so the LCD is only called if the IntFlag is set.

I dont have the floating point option from Oshonsoft, so I have changed Single to Word variable, the program runs OK.
E

SwingeyP · Jan 31, 2014

Just a quickie,

This doesn't work

Select Case arg1
Case >= 7 and < 7.1

Is this type of syntax possible or do I need a lot of ifs?

Cheers - Paul

SwingeyP · Jan 31, 2014

Interestingly when I take the LCD calls out and put them in the interrupt I get hardware stack overflow errors?

ericgibbs · Jan 31, 2014

SwingeyP said:
Interestingly when I take the LCD calls out and put them in the interrupt I get hardware stack overflow errors?

hi,
Dont put the LCD in the ISR, the PIC Stack is only 8 deep.

Code:

Select Case var1     
        Case >= 7 ' allowed but =>7  is not, also only one Case Test is allowed per Case.
    ''''
        Case Else
    EndSelect
Goto main

You may find this revamped version of the Oshonsoft manual easier to use.
I rewrote the manual and posted it to the Oshonsoft site back in 2010
Eric

SwingeyP · Jan 31, 2014

Well here's my version so far guys I hope it helps anyone that might be as stuck as I was.

Thanks for the updated manual Eric - Very useful

I have done quite a few alterations and added a bit more functionality. It's still a bit scrappy (I think I might need to tidy a few things up) but this is doing what I had hoped (in simulation).
How this performs in real life - well hopefully i'll get a test up and running over the weekend and get something on YouTube.

ericgibbs · Feb 1, 2014

hi Paul,
Ran your last Basic program OK.
My concern is the amount of time the program uses in servicing the LCD.
If the User turns the Encoder too quickly, you could get missed direction changes or get Stack overflows.

The CALL functions will use the Stack, also the LCD Basic uses the Stack.
E

SwingeyP · Feb 1, 2014

Hi Eric. I aslo have these concerns but i'm not sure how to deal with it. Maybe i'll have to lose the analog display or do was many have done and split the operation for the LCD to another pic.

At present i'll go with it and see what happens.

ericgibbs · Feb 1, 2014

hi Paul,
If you have the hardware 'sort of' built' try the program in a PIC, lets know what you get. [ dont forget to rem out the Define SIMULATION_WAITMS_VALUE = 1 or make = 0.]
Eric

SwingeyP · Feb 5, 2014

Aghhhhh - It's driving me nuts! - Can anyone tell the correct configuration for the 16f876 please? I am using an external 4mhz OSC on pins 9 & 10. I tend to avoid using external xtals for just this reason. Always drives me mad. I just cant get the PIC to run :-(

Can anyone help please?

ericgibbs · Feb 6, 2014

hi Paul,
You should have these two lines on your program Header.

Define CONFIG = 0x3d71 'Ext 4MHz Oscillator'
Define CLOCK_FREQUENCY = 4

To set/check the CONFIG for any Oshonsoft PIC.

Top Menu Bar, click.
Options/Configuration Bits

[Refer attached image]
Use the 'Toggle View [1/4]' button to Step thru the way the CONFIG labels are displayed.

Adjacent to each label is a drop down arrow, click and select your CONFIG options.

When done, Click 'Generate Basic Code' button, this will place the Define CONFIG xxxx at the head of your Basic program listing.
Click 'Accept' button when done.

You should have on your project board a 15pF or 22pF cap from each leg of the Xtal to 0v.

Post a photo of your project board if you have a problem.

Eric.

EDIT:
Ensure that the /MCLR pin if used, is correctly connected and not 'floating'

SwingeyP · Feb 6, 2014

Hello Eric. Many thanks for the speedy reply. I spent ages trying to sort this out last night and within 2 mins this morning I have it oscillating
This I have to admit was down to my eyesight and simple wood for the trees. It seems the circuit prefers 22pf and not 22nf. I now have the opening screen displayed on the LCD which is just sitting there doing nothing at present. I'll investigate further and post my findings for anyone else following this thread.

BTW - I found this datasheet most helpful --> https://ww1.microchip.com/downloads/en/DeviceDoc/31002a.pdf
I hope it's ok to post links here.

Cheers Paul

camerart · Feb 6, 2014

SwingeyP said:
Hello Eric. Many thanks for the speedy reply. I spent ages trying to sort this out last night and within 2 mins this morning I have it oscillating
This I have to admit was down to my eyesight and simple wood for the trees. It seems the circuit prefers 22pf and not 22nf. I now have the opening screen displayed on the LCD which is just sitting there doing nothing at present. I'll investigate further and post my findings for anyone else following this thread.

BTW - I found this datasheet most helpful --> https://ww1.microchip.com/downloads/en/DeviceDoc/31002a.pdf
I hope it's ok to post links here.

Cheers Paul

Hi Paul,

Good that you have the Oascillator working. I was drawing this before you replied, so I've posted it anyway, it's for a Crystal, which I prefer if I'm making a 'proper' circuit.

Camerart

SwingeyP said:
Hello Eric. Many thanks for the speedy reply. I spent ages trying to sort this out last night and within 2 mins this morning I have it oscillating
This I have to admit was down to my eyesight and simple wood for the trees. It seems the circuit prefers 22pf and not 22nf. I now have the opening screen displayed on the LCD which is just sitting there doing nothing at present. I'll investigate further and post my findings for anyone else following this thread.

BTW - I found this datasheet most helpful --> https://ww1.microchip.com/downloads/en/DeviceDoc/31002a.pdf
I hope it's ok to post links here.

Cheers Paul

Hi Paul,

Good that you have the Oascillator working. I was drawing this before you replied, so I've posted it anyway, it's for a Crystal, which I prefer if I'm making a 'proper' circuit.

Camerart

SwingeyP · Feb 6, 2014

Hi everyone. After much messing with and learning about MCLR, pull up and pull down resistors here's what I have. It's still in it's infancy (sorry about the birds nest) but i seems to work. No debounce on the interrupt with a push button. Will be interesting to see how the encoder performs. Just waiting for a 4030B or a 7486 quad XOR gate. You can just see the bread board with the start of the encoder.

If it's ok i'll keep posting until I have the correct sine wave from the AD9850 for people to follow and i'll try and do something for an article Eric.

Cheers - Paul

ericgibbs · Feb 7, 2014

hi Paul,
Thats looking good, it will make a great Article, but take your time.
Eric

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