Comments on: Circuit Description

By: Dave

Dave — Thu, 11 Mar 2010 12:52:18 +0000

R6-12 can be omitted completely (there’s no need to tie those pins to VCC because there are internal pullup resistors). Also, you can obtain another PIC from FAR Circuits–just email them and ask for a price.

By: Craig Combes

Craig Combes — Thu, 04 Mar 2010 04:13:13 +0000

Hi Dave,
I got the Bluetooth module today and it’s a surface mount module that would look much nicer properly mounted on a new board, so I’m going to do a new board (after I wire into your current board to make sure it works).
I was reviewing your schematic and I was wondering if you felt that R6-R12 were really necessary? Can’t those pins all be tied to VCC directly? Also, how could I go about getting another PIC?

Thanks!

Craig Combes

By: Dave

Dave — Sat, 13 Feb 2010 01:53:01 +0000

1) The z command sets the encoder resolutions (ticks per axis revolution):

A = declination resolution low byte
B = declination resolution high byte
C = right ascension resolution low byte
D = right ascension resolution high byte

declination resolution is 256*B + A
right ascension resolution is 256*D + C

So if the resolution on the declination axis is 4000, then the high byte is 15 and the low byte is 160 (15*256 + 160 = 4000).

2) declination position is 256*B + A, and right ascension is 256*D + C.

By: Willy

Willy — Sat, 13 Feb 2010 00:32:58 +0000

Hello,

I need more information for communications protocol :
I have 2 encoders with 4000 ticks, so

1) if i send the command ‘zABCD’, what is the value of A,B,C and D ?

2) if i send the command ‘h’, i receive ‘ABCD’. The declination position is Ax256+B ?

Thanks for your help.