RE: [bascom] AVR: Rotary Encoders

["Albert L. Tiu" <a_tiu@pacific.net.ph>]

Andrew,

Try this.  I used optical encoders, a delay can be inserted and the time
delay must be suited to the specs of your mechanical encoder. I did not use
external pull up and enable the uC pull up, which is about 100K.  Channel A
is ahead of Channel B by 90 degrees if turned clockwise.

Used 2313 on this one, you can use other uC but connect ChA to INT0

Dim Count As Integer

Ddrd = &H00                                                 'Port D as Input
Portd = &HFF                                                'Enable Pull Ups

Config Int0 = Rising                                                    
'Configure INT0 for Rising Edge of the encoder
ChA Signal

Ch_a Alias Pind.2                                           'Channel A
connected to INT0 pin
Ch_b Alias Pind.0                                           'Channel B can
be connected to any other pins

Enable Interrupts
Enable Int0                                                 'enable the
interrupt
On Int0 Chkpins                                             'jump to Chkpins
on INT0

Start:
Print "Current Count Is " ; Count
Idle
Goto Start:

Chkpins:
'Waitms 10                                                                    
  'insert this delay for debounce if you use mechanical
encoder
If Ch_a = 1 Then
   If Ch_b = 0 Then Count = Count + 1 Else Count = Count - 1
End If
Return



-----Original Message-----
From: owner-bascom@grote.net [mailto:owner-bascom@grote.net]On Behalf Of
Andrew & Rhonda
Sent: Friday, September 07, 2001 2:54 PM
To: bascom@grote.net
Subject: [bascom] AVR: Rotary Encoders


Before I re-invent the wheel, has anyone interfaced a 2 bit gray scale
rotary encoder
to and AVR???

I was thinking -
Common to GND
A & B to AVR input port

Are the internal pull-ups enough???

I dont need to determine velocity, just count up & down

any help appreciated.

Andrew