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cybanical
Joined: 10 Apr 2008
Posts: 6
Location: Oakland, CA
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| thanks |
 Posted: Tue Apr 15, 2008 10:00 am |
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Great, thanks for the direction, that makes sense. I found the memory organization charts in the data sheets (table 5.1 for the 18f4520), I had looked before but didn't really know what i was looking for.
I made an R/2R ladder last night and managed to turn my encoder into a pot. Next for me is to determine velocity and turn that into a velocity.
_________________
cybanical == cyber+mechanical |
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EC
Joined: 26 Aug 2008
Posts: 3
Location: Belgium
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| Rotary Encoder (Fast and Slow Mode) |
| Posted: Tue Aug 26, 2008 10:06 am |
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| Ttelmah wrote: |
| Code: |
int16 position;
#int_global
void myint(void) {
static int old;
static int new;
static int value;
//Here I have an edge on one of the quadrature inputs
new=portb;
/*Now I have to decode the quadrature changes. There are four
possibilities:
I can have a rising or falling edge, on each of the two inputs. I have to
look at the state of the other bit, and increment/decrement according to
this. */
value=new^old;
//'value', now has the bit set, which has changed
if (value & 0x10) {
//Here the low bit has changed
if (new & 0x10) {
//Here a rising edge on A
if (new & 0x20) --position;
else ++position;
}
else {
//Here a falling edge on A
if (new & 0x20) ++position;
else --position;
}
}
else {
//Here the high bit (B) must have changed
if (new & 0x20) {
//Here a rising edge on B
if (new & 0x10) ++position;
else --position;
}
else {
//Here a falling edge on B
if (new & 0x10) --position;
else ++position;
}
}
old=new;
bchanged=0;
#asm
//Here the 'fast' exit.
RETFIE 1
#ENDASM
}
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Hello,
I'm use a rotary encoder switch from ALPS (EC12 series) and the code from Ttelmah works perfectly with it! But, I'd like have two levels when I'm increase or decrease a counter variable.
Like this: in Normal(slow) mode, I'm increase/decrease per one unit and in Fast mode, per ten units.
How can I change the code to do what I want?
Thanks in advance,
EC |
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Ttelmah
Guest
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| Posted: Tue Aug 26, 2008 10:23 am |
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You would need to do something like:
| Code: |
int16 position;
int1 big_increment=FALSE;
#int_global
void myint(void) {
static int old;
static int new;
static int value;
//Here I have an edge on one of the quadrature inputs
new=portb;
/*Now I have to decode the quadrature changes. There are four
possibilities:
I can have a rising or falling edge, on each of the two inputs. I have to
look at the state of the other bit, and increment/decrement according to
this. */
value=new^old;
//'value', now has the bit set, which has changed
if (value & 0x10) {
//Here the low bit has changed
if (new & 0x10) {
//Here a rising edge on A
if (new & 0x20) {
if (big_increment) position-=10;
else --position;
}
else {
if (big_increment) position+=10;
else ++position;
}
}
else {
//Here a falling edge on A
if (new & 0x20) {
if (big_increment) position+=10;
else ++position;
}
else {
if (big_increment) position-=10;
else --position;
}
}
}
else {
//Here the high bit (B) must have changed
if (new & 0x20) {
//Here a rising edge on B
if (new & 0x10) {
if (big_increment) position+=10;
else ++position;
}
else {
if = (big_increment) position-=10;
else --position;
}
}
else {
//Here a falling edge on B
if (new & 0x10) {
if (big_increment) position-=10;
else --position;
}
else {
if (big_increment) position+=10;
else ++position;
}
}
}
old=new;
bchanged=0;
#asm
//Here the 'fast' exit.
RETFIE 1
#ENDASM
}
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Then set 'big_increment' to true when you want the fast increment, and false, when not.
This will slightly reduce the maximum speed the encoder can be handled, but for a normal rotary wheel shouldn't matter.
Best Wishes |
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EC
Joined: 26 Aug 2008
Posts: 3
Location: Belgium
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| Posted: Tue Aug 26, 2008 10:44 am |
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| Ttelmah wrote: | You would need to do something like:
Then set 'big_increment' to true when you want the fast increment, and false, when not.
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Hi Ttelmah,
First, thanks for your quick answer.
I understand the principle with "big_increment" but at which moment must I set or clear this flag?
Best regards,
EC |
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Ttelmah
Guest
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| Posted: Tue Aug 26, 2008 2:56 pm |
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When you want the larger increment.....
You have not said how you want to trigger this. I'd assume you are going to use a button or something?.
Best Wishes |
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EC
Joined: 26 Aug 2008
Posts: 3
Location: Belgium
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| Posted: Tue Aug 26, 2008 3:27 pm |
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Maybe, a little more explain to what I'm working is welcome 
I'd made a Countdown Timer with a rotary encoder switch (EC12 from ALPS) and a relay.
I have also two buttons: one for start/stop and other one for Reset timer.
The principle of "Fast" and "Slow" mode then I'd like reproduce, It's like the "big button" of a generator functions to choose the Frequency. In this case, if you turn slowly, it's increment/decrement per unit but if you turn faster, it's increment/decrement per 10 or whatever without triggered with a button.
I hope You see my goal with the rotary encoder.
Best Regards,
EC |
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