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Science Forum Index » Electronics Forum » 6802 clock
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Message |
| Lee K. Gleason |
 Posted: Thu Jul 21, 2005 6:07 pm |
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I'm building a simple 6802 single board system. I want to drive the CPU
with an external oscillator, rather than using a crystal (got lots of 4 pin
oscillators, not so many crystals). When using a crystal, the frequency of
the crystal gets divided down by 4 by an internal part of the processor (so
you use a 4 MHz crystal for a 1MHz clock).
When using an external oscillator, like I want to do, does the same divide
by 4 occur? That is, should I use a 4 MHz external oscillator, or a 1 MHz
oscillator for a 1 MHz system clock?
Lee K. Gleason N5ZMR
Control-G Consultants
lgleason@houston.rr.com |
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| John Fields |
| Posted: Thu Jul 21, 2005 6:13 pm |
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On Thu, 21 Jul 2005 23:07:49 GMT, "Lee K. Gleason"
<lgleason@houston.rr.com> wrote:
Quote: I'm building a simple 6802 single board system. I want to drive the CPU
with an external oscillator, rather than using a crystal (got lots of 4 pin
oscillators, not so many crystals). When using a crystal, the frequency of
the crystal gets divided down by 4 by an internal part of the processor (so
you use a 4 MHz crystal for a 1MHz clock).
When using an external oscillator, like I want to do, does the same divide
by 4 occur? That is, should I use a 4 MHz external oscillator, or a 1 MHz
oscillator for a 1 MHz system clock?
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You'll need a 4MHz oscillator.
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John Fields
Professional Circuit Designer |
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| Bozzion |
| Posted: Thu Jul 21, 2005 6:14 pm |
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"Lee K. Gleason" <lgleason@houston.rr.com> wrote in message
news:9VVDe.11159$gL1.10218@tornado.texas.rr.com...
Quote: I'm building a simple 6802 single board system. I want to drive the CPU
with an external oscillator, rather than using a crystal (got lots of 4
pin
oscillators, not so many crystals). When using a crystal, the frequency of
the crystal gets divided down by 4 by an internal part of the processor
(so
you use a 4 MHz crystal for a 1MHz clock).
When using an external oscillator, like I want to do, does the same
divide
by 4 occur? That is, should I use a 4 MHz external oscillator, or a 1 MHz
oscillator for a 1 MHz system clock?
Lee K. Gleason N5ZMR
Control-G Consultants
lgleason@houston.rr.com
why not? isn't the devider on chip? |
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| Frank |
| Posted: Fri Jul 22, 2005 5:43 pm |
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No I was just asking?
Motorola came up with a good range of micro, I went to a few of there
seminars, back in the 70's
John Fields <jfields@austininstruments.com> wrote in message
news:4852e1h6j3u97fvp443n5jg4vt92p6gh04@4ax.com...
On Sat, 23 Jul 2005 01:52:00 +1200, "Frank" <some1not@microsoft.com>
wrote:
Quote: By the way who makes the 6802, is Motorola still around?
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Motorola spun off their µC product line to Freescale Semiconductor,
but I don't think you're going to find much 6802 around, since it's
been obsolete for a while.
Freescale suggests Rochester Electronics as a possible source, and
Google will give you lots of hits. If what you're doing is new, why
do you want to use a 6802 anyway?
If you choose to reply, it's considered, in this group, to be
courteous if you bottom post.
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John Fields
Professional Circuit Designer |
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| Rich Grise |
| Posted: Sat Jul 23, 2005 10:55 am |
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On Sat, 23 Jul 2005 08:59:29 -0500, John Fields wrote:
Quote: On Sat, 23 Jul 2005 01:16:04 GMT, "Karl Uppiano"
"Frank" <some1not@microsoft.com> wrote in message
No I was just asking?
Motorola came up with a good range of micro, I went to a few of there
seminars, back in the 70's
John Fields <jfields@austininstruments.com> wrote in message
01:52:00 +1200, "Frank" <some1not@microsoft.com> wrote:
By the way who makes the 6802, is Motorola still around?
Motorola spun off their µC product line to Freescale Semiconductor,
but I don't think you're going to find much 6802 around, since it's
been obsolete for a while.
Freescale suggests Rochester Electronics as a possible source, and
Google will give you lots of hits. If what you're doing is new, why do
you want to use a 6802 anyway?
Sometimes a good 8-bit 1 MHz processor is all you need.
Yes, but that's not the point, which is that the 6802 is obsolete and only
available from "surplus" dealers.
For a desperate one-off, that might be OK, but going through the expense
and hassle of stepping back in time when _many_ good 8 bit µC are
available for cheap in the present hardly makes the exercise seem worth
while.
John is absolutely right. For the effort it would take to track down
data sheets and crap on that old of a part simply doesn't make any
sense. I did a quick google on "6802 data sheet", without the quotes,
and out of thousands of answers, none of them was about the old Moto
micro. Heck, I saw a Basic Stamp Development Kit in Fry's not too
long ago, for about a hundred and twenty-five bucks.
What country are you in?
Good Luck!
Rich |
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| Jim Adney |
| Posted: Sun Jul 24, 2005 11:10 am |
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On Fri, 22 Jul 2005 10:51:42 -0500 John Fields
<jfields@austininstruments.com> wrote:
Quote: If you choose to reply, it's considered, in this group, to be
courteous if you bottom post.
Gee, John, just being difficult, or trying to start a war?
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Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
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