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- ClueLess
February 23, 2008, 3:07 pm

Hi all
I am just toying with 89C2051 and I have assembled a program to switch
on a series of LEDs using the rl a instruction. The program works well
on the simulator. But I cannot make it work on the breadboard.
The problem is with the reset. I am using an available 32.768kHz
crystal, I have used the standard 33pf caps too.
On the reset pin I have tried 1 uf, 10uf capacitors and also
resistances of various values to the ground from the reset pin. Still
no go.
Can someone in the know among you help me with some leads?
Thanks for your time and attention
ClueLess
--

Re: Rest problem 89C2051
On Sat, 23 Feb 2008 16:07:40 +0000, Eeyore

Since I did not have a 12pf cap handy I tried with a 4 mHz crystal
with 33pf caps. Still no go. As I said the code works very well in the
simulator.
Any more suggestions?
Thanks for taking time to help me
ClueLess
PS: Did not see this after several hours. So posting again :-(
--

Re: Rest problem 89C2051

Could be alot of things.
Are you declaring variables in ROM space? Would work with emulator.
If you are using a software emulator, make sure you recompile with that
option off.
Are you compiling within ROM space addresses?
Are you using RAM within RAM space limits?
etc...

Re: Rest problem 89C2051
ClueLess wrote:

You mean it's OK now ? Good to hear.

I expected it to want less capacitance actually !

Do you have the manufacturer's data for that specific crystal you are using
? If not, you need to get it.
Beware of things like stray capacitance from PCB traces and also it may be a
good idea to ground the cystal's metal can.
Graham

Re: Rest problem 89C2051
On Tue, 26 Feb 2008 19:15:14 +0000, Eeyore

The data sheet says 12.5 pf which I do not have at the moment,
unfortunately. I will have to order it.
Meantime I modified the program to work with a 4 mHz crystal and 33 pf
caps and it worked first shot.
So it is only the crystal interfacing - the key is in the caps, I
think.
I will post the results once I get hold of the 12.5 pf stuff.
Thanks for your continued interest in helping me
ClueLess
--
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