6502.org Forum  Projects  Code  Documents  Tools  Forum
It is currently Thu Nov 14, 2024 1:57 am

All times are UTC




Post new topic Reply to topic  [ 13 posts ] 
Author Message
 Post subject: Clock sources
PostPosted: Tue Oct 25, 2011 1:26 am 
Offline
User avatar

Joined: Mon Aug 08, 2011 2:48 pm
Posts: 808
Location: Croatia
Could you post your clock sources schematics, i only know how to rig a 4060 as a crystal oscillator, so i would like something that can actually run faster than 4MHz...


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Tue Oct 25, 2011 2:02 am 
Offline
User avatar

Joined: Fri Aug 30, 2002 1:09 am
Posts: 8540
Location: Southern California
A couple of old but good ap. notes from Fairchild:
HCMOS crystal oscillators: http://www.fairchildsemi.com/an/AN/AN-340.pdf
CMOS oscillators: http://www.fairchildsemi.com/an/AN/AN-118.pdf

It's often most productive however to just use one of the off-the-shelf oscillator cans that take the space of an 8- or 14-pin DIP. This will make sure the oscillator will always work correctly for the whole voltage and temperature range, and it's easy to change.

Image


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Tue Oct 25, 2011 11:25 am 
Offline

Joined: Mon Mar 02, 2009 7:27 pm
Posts: 3258
Location: NC, USA
I made this last year. It works well, except the 74S124 uses some current.
Might be a little more money, but it's better then buying multiple crystals/cans.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Tue Oct 25, 2011 2:29 pm 
Offline
User avatar

Joined: Mon Aug 08, 2011 2:48 pm
Posts: 808
Location: Croatia
GARTHWILSON wrote:
It's often most productive however to just use one of the off-the-shelf oscillator cans that take the space of an 8- or 14-pin DIP. This will make sure the oscillator will always work correctly for the whole voltage and temperature range, and it's easy to change.


I would love to do that, if just there were any to buy... They don't really sell them in electronic stores here where am I, and also are kinda rare on ebay...

So i am left whit crystals self made oscillators...

And thanks for the schematics...

One more question, will it work if i use a 74LS01 or other 74LS as an inverter?


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Tue Oct 25, 2011 4:13 pm 
Offline
User avatar

Joined: Mon Dec 08, 2008 6:32 pm
Posts: 143
Location: Brighton, England
TTL Chips (74LS, etc) need a different circuit to CMOS gates.
The one I use is as follows
Code:
    470 ohm            470 ohm
    ----               ----
 --|    |--         --|    |--
|   ----   |       |   ----   |
|          |       |          |
|  |\      |  10n  |  |\      |     |\
|--| >O--------||-----| >O----------| >O---
|  |/                 |/    |       |/
|                           |
 -------------|X|-----------


This has worked reliabally with crystals from 1MHz to 18MHz using a 74LS04 or 74S04 device.

_________________
Shift to the left,
Shift to the right,
Mask in, Mask Out,
BYTE! BYTE! BYTE!


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Tue Oct 25, 2011 4:26 pm 
Offline
User avatar

Joined: Mon Aug 08, 2011 2:48 pm
Posts: 808
Location: Croatia
Thanks! :D


Top
 Profile  
Reply with quote  
 Post subject: Re: Clock sources
PostPosted: Wed Jan 02, 2013 8:06 am 
Offline
User avatar

Joined: Fri Aug 30, 2002 1:09 am
Posts: 8540
Location: Southern California
In trying to figure out what some obviously erroneous oscillator data in a PIC microcontroller data sheet should have been (yes, there are other companies besides WDC that have errors in their data sheets), I came across this page that links some more ap. notes on crystal oscillator design near the top: http://www.microchip.com/forums/m49934.aspx

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?


Top
 Profile  
Reply with quote  
 Post subject: Clock Sources
PostPosted: Sat Jan 12, 2013 6:54 pm 
Offline
User avatar

Joined: Thu May 28, 2009 9:46 pm
Posts: 8483
Location: Midwestern USA
Here's the clock generator circuit I used in POC V1. It produce an output frequency that is one-half that of the can oscillator that drives it.

Attachment:
File comment: Two phase clock generator.
clock_gen.jpg
clock_gen.jpg [ 262.75 KiB | Viewed 15366 times ]

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!


Top
 Profile  
Reply with quote  
 Post subject: Re: Clock sources
PostPosted: Sun Jan 13, 2013 12:14 am 
Offline
User avatar

Joined: Mon Aug 08, 2011 2:48 pm
Posts: 808
Location: Croatia
Phi1 and Phi2 shown on the schematic are not the same as the one generated by the 6502, since the 6502 splits the clock on his own.
In my new cpu board I use a 74HC393 counter to get multiple clocks(I have rotary switch for selecting clocks).


Top
 Profile  
Reply with quote  
 Post subject: Re: Clock sources
PostPosted: Sun Jan 13, 2013 6:11 am 
Offline
User avatar

Joined: Thu May 28, 2009 9:46 pm
Posts: 8483
Location: Midwestern USA
Dajgoro wrote:
Phi1 and Phi2 shown on the schematic are not the same as the one generated by the 6502, since the 6502 splits the clock on his own.

That's correct. However, this clock generator is on my W65C816S-powered POC. For other applications just ignore the phase you don't need. Also note that the two phase clock is not required with the W65C02S. That was an NMOS "feature." All timing on WDC microprocessors is based on the Ø2 clock only.

Quote:
In my new cpu board I use a 74HC393 counter to get multiple clocks (I have rotary switch for selecting clocks).

Tick-tock. :D

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!


Top
 Profile  
Reply with quote  
 Post subject: Re: Clock sources
PostPosted: Sun Jan 13, 2013 11:41 pm 
Offline
User avatar

Joined: Mon Aug 08, 2011 2:48 pm
Posts: 808
Location: Croatia
What about making a more advanced clock source with a custom clock divider, so it can divide by 2,3,4,5, etc... Maybe a fast oscillator with a ring counter could be used.
Also software clock settings would be nice.


Top
 Profile  
Reply with quote  
 Post subject: Re: Clock sources
PostPosted: Mon Jan 14, 2013 3:29 am 
Offline
User avatar

Joined: Fri Aug 30, 2002 1:09 am
Posts: 8540
Location: Southern California
Dajgoro wrote:
What about making a more advanced clock source with a custom clock divider, so it can divide by 2,3,4,5, etc... Maybe a fast oscillator with a ring counter could be used.
Also software clock settings would be nice.

That sounds more or less like the Maxim/Dallas DS1077 and the DS1085, both of which work at 5V and need no external components. They don't have crystal accuracy, but about 1% error which is good enough for RS-232, and the frequency can be programmed via I²C, from 8.1kHz to 133MHz.

Image

If accuracy is not important at all and you just want to see how fast you can run it up before the computer starts having problems, you can make a relaxation oscillator whose frequency varies with a pot, like so:

Image

That one goes to 73MHz. Below is an earlier one I did which is slower:

Image

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?


Top
 Profile  
Reply with quote  
 Post subject: Re:
PostPosted: Wed Aug 14, 2013 12:45 am 
Offline
User avatar

Joined: Mon Aug 08, 2011 2:48 pm
Posts: 808
Location: Croatia
PaulF wrote:
TTL Chips (74LS, etc) need a different circuit to CMOS gates.
The one I use is as follows
Code:
    470 ohm            470 ohm
    ----               ----
 --|    |--         --|    |--
|   ----   |       |   ----   |
|          |       |          |
|  |\      |  10n  |  |\      |     |\
|--| >O--------||-----| >O----------| >O---
|  |/                 |/    |       |/
|                           |
 -------------|X|-----------


This has worked reliabally with crystals from 1MHz to 18MHz using a 74LS04 or 74S04 device.

It also works fine with a 7404, I tested it at 10MHz.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 13 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 11 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to: