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POWER to the PIC !
Hi ustredna,
What everyone here is trying to explain, but not quite doing is this:
The PIC oscillator requires a bit more power to operate at speeds above 4mhz.
you set the program parameters to be correct in your code for the oscillator speed with your DEFINE OSC 20 statement, but you tell the programmer to enable the oscillator to use the high power setting with the config fuse, or by manualy selecting HS on the programmer's software, elsewise your Oscillator is not going to work.
JS
If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
.
Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants - but debt is the money of slaves
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There simply is no "Happy Spam" If you do it you will disappear from this forum.
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Last edited by JD123; - 13th March 2008 at 23:06.
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you will have to edit your 16F877A.inc file as below.
NOLIST
ifdef PM_USED
LIST
include 'M16F87xA.INC' ; PM header
device pic16F877A, HS_osc, wdt_OFF, lvp_off, protect_ON , CP_ON
XALL
NOLIST
else
LIST
LIST p = 16F877A, r = dec, w = -302
INCLUDE "P16F877A.INC" ; MPASM Header
__config _HS_OSC & _WDT_OFF & _LVP_OFF & _CP_OFF
NOLIST
endif
LIST
Your 16F877A will work on 20Mhz.
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My Opinion
Hi ustredna,Originally Posted by precision
The file mentioned above is included into your code automaticly when you compile using PBP and it contains "Default Settings" for your config statements, so if you do not include config statements in YOUR CODE it will default to the settings in this file. If you change the settings here it will DEFAULT to whatever you set here. Now for my opinion: I would not change the default to 20 mhz, I would instead simply put a semicolon at the beginning of the config statements so as to make the compiler overlook them as comments, and then include my own config statements in "MY CODE" every time.
JS
edit: Oh BTW, each PIC type has it's own file like this.
If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
.
Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants - but debt is the money of slaves
.
There simply is no "Happy Spam" If you do it you will disappear from this forum.
|
My experience on this
Hi,
Ive the same problem, i thange the crystal, caps, code... and nothing (at 1st time when y bought it works on 20mhz).Then today i went to the store ans bougt one pic more, caps, clocks. The problem was on the the 1st pic!!! i was not very good only acepts 4mhz clocks.
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Re: 16F877A with 20MHz XTAL not working?
thx, this one works.
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