'(Fwd) Re: 12C508 too fast partial solution?'
|Again, this message was inadvertently sent only to me; I'm forwarding
it to the PICLIST.
------- Forwarded Message Follows -------
Date: Fri, 31 Jan 1997 22:39:45 -0600 (CST)
From: Todd Peterson <netins.net> elab
Subject: Re: 12C508 too fast partial solution?
At 01:01 PM 1/31/97 -0800, Andrew Warren wrote:
>Yes, there's someone (I forget his name now) from CCS on the list.
>That is, he USED to be here... I haven't seen any messages from him
>since someone posted a long list of CCS-compiler bugs to the list
>three weeks ago.
I have found two distinct problems here; the first was a CCS compiler
error; however they did graciously fix the compiler bug problem
The second is that, no matter what value is written to OSCCAL (the
upper 4 bits are the only ones that matter), I cannot change the speed
of the clock. Yes, my scope is perfectly calibrated; it has a 1KHz
calibration plug that shows exactly calibrated; and besides I should
see a change anyway when moving the PIC's calibration constant from 10
to 70. My question is: do others have this working? If you think you
do, you might not; the device does power up to a default of 70 and you
might not be really calibrating the RC value from that. I do read the
hex file back from the programed chip every time to verify that the
last location (the cal. constant) was programmed correctly. I get a
.8 mS high time from the output pin regardless of the cal. constant
loaded into OSCCAL.
I hate to mess with the delay loops I know work, 'cause unsolved
problems like this invariably come back to bite you. I would actually
be happy if I could verify that someone IS actualy tuning their R/C
properly, and not just using the powerup value of 70. Be careful, the
last location of memory reading back as your constant is not proof it
is working; you must actually watch signals on I/O pins.
|Hi Andy, &c.
> Again, this message was inadvertently sent only to me; I'm forwarding
> it to the PICLIST.
Your mailer sends out a reply-to header and some list servers leave it
there if it exists and otherwise put in the list address as reply-to.
If you send mail from only one account then you could remove your reply-to
header if this symptom starts to get to you.
I have written a short program to do what you need. Works like a bomb
and as it only uses 9 bytes you can use it in a OTP and then just
program the bytes to NOPS after you are done if you must use it later.
I realise when I was testing that the B on the lid of one of my
devices was infact a 3 and this could explain some of my own timing
problems I had while testing code. The graph illustrates the way
the frequency changes. It shows percent from the ideal values.
Check out the following URL :
Kalle Pihlajasaari ip.co.za kallehttp://www.ip.co.za/ip
Interface Products P O Box 15775, DOORNFONTEIN, 2028, South Africa
+ 27 (11) 402-7750 Fax: 402-7751 http://www.ip.co.za/people/kalle
DonTronics, Silicon Studio and Wirz Electronics uP Product Dealer
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