Hi,
I'm doing a design with W65C134S. I'm a little unsure about the design around the crystals as the datasheet is a little unclear. Does the following look reasonable to you ??

The clock signals FCLKO, FCLK, CLKO and CLK goes to the respective pin on the MCU.

Regards
/Pontus

Your circuit is what's shown on http://www.6502.org/archive/datasheets/ ... y_2003.pdf page 58. I have no doubt however that R2 and R3 are swapped on their diagram. I'm sure it wouldn't work as shown. I also don't know why they bother to give non-standard resistor values on something that's not that critical! 18 or 22 ohms will work fine for the 20 ohm resistor, 820K for the 800K, and 2.7M for the 2.6M.

Hello Pontus,

Well, its good to see someone else finally playing around with WDC's
microcontrollers ! I have not used the 134, but use the 265 and am very
happy with it ; good luck !

The oscillator you are refering to is commonly called a ' Pierce
Oscillator '. If you enter this in GOOGLE, you will get lots of hits.

If you refer to this link :

http://www.rockhounding.net/projects/co ... rts/32768/

You will see a configuration very close to what WDC shows on the
134 datasheet. On this page, you will also find a very good started app.
at this link :

http://www.ee.washington.edu/circuit_ar ... Schem.html
This one will give you some rules of thumb which help to explain
component values.

I have some datasheets squirrelled away at home which show the
series resistor configured both ways. One like WDC has drawn it, and two
with the series resistor between the Parallel feedback resistor and the
component ( 74HC gate, micro etc ) it is terminated to. This topic has been
an issue with me too, maybe I can find some additional pdf's when I get
home which might help.

As Garth points out, there is some flexibilitywith component values.

Personally, I have started using Epson's SG-51 series of canned
oscillators for the Fast clock. They are compact, cheap, and allow quick
swapping if you want you Fast clock faster or slower. However, I have yet
to find a small, readily availible 32Khz unit.

Hopefully I am not repeating information you may already know
but, The internal MASK ROM Monitor in the 134 uses the 32Khz time base
to calculate what the Fast Clock frequency is. This was done to allow auto
startup of the ROM with different fast clock freq's. Stay with the 3.6864Mhz
Fast clock until you get everything going. I have tried different Fast clks
with my current W65C265 project and I am having trouble getting the
Monitor to startup with anything but 3.6864. ( Hopefully this is unique to the
265 and not the 134 ) The Internal ROM is HANDY !, and allows you to
exchange a RAM chip in the ROM space, and download ROM images into
RAM for program developemnt. This gets you away from the Assemble /
Burn / Test cycle when you are trying to get and app. like FORTH off the
ground. Once you have it running, you can swap a ROM in and bypass the
MASK altogether.

One thing I hope to try, is using 1Mhz for the slow clock and a
4+Mhz unit for the Fast clock on my next 265 unit. If I am understanding
WDC's docs correctly, this MAY still allow the auto Fast Clock detection with
the Internal ROM. In fact look for a picture on WDC's site of a 265
developer board. It shows this combo if I remember correctly.

Anyway, as you can tell, I have been looking for an excuse to get
more people interested in using the 134 & the 265. :-)


Good Luck, Wally

OK, Here is some more info :

http://www.semiconductors.philips.com/a ... 7090_1.pdf

http://www.eetkorea.com/ARTICLES/2001SE ... AMD_AN.PDF

http://www.zilog.com/docs/z8/appnotes/on_chip.pdf

&

http://www.freescale.com/files/netcomm/ ... AN2049.pdf

You may find it might pay to download some of these app notes for
future reference. I noticed some of them are not so easy to find online
anymore.

Hopefully there are enough links to usefull info to get you going.

Good Luck !

- Wally

Thanks a million guys,
That was extremly helpful replies. I have never dug into oscillator basics before but that was really fun.

/Pontus

Good Luck,

Please keep us informed with your experiences with the 134.
It and the 265 are good chips to work with at the hobbyist level.

Best Wishes, Wally

Wally,
I'll try to keep you posted even though this is a commersial project.
The 65c02 and its derivatives are great to work with, especially for me with more than 20 years of experience with the little guy

/P

Hi Pontus

Thank-You & Good Luck !

- Wally