Discussion in "Project Help" started by    eddieprice    Jan 12, 2018.
Fri Jan 12 2018, 04:32 PM
#1
I am using a 16F84A for the first time and am having trouble with the oscillator. I am using a 4 MHz xtal with 22pf capacitors as shown in the PIC16F84A datasheet. I have used MPLAB IDE V8.91 to write the program. The simulation works fine, but the circuit doesn't. I have a small didgital oscilloscope and I would assume that I should be able to observe a square wave across the xtal - but there is nothing. This is my configuration code:-
__CONFIG _CP_OFF & _WDT_OFF & _PWRTE_ON & _XT_OSC
Any suggestions would be much apprciated.
Fri Jan 12 2018, 06:49 PM
#2
Sometimes the Configuration word has to be programmed separately.
Check your programming software to make sure the
Configuration word is being set correctly.

Check the reset pin is high after a short delay.
Check all your connections again.. and carefully.

Write a simple flashing LED program, does it work using
the R/C oscillator ?

FYI.. the 16F84A is now very old, and expensive, due to rarity value.
It is messy to program in assembly and has too little memory
to do much in C.
Consider moving to a newer device.



[ Edited Sat Jan 13 2018, 02:56 AM ]

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Posted By ExperimenterUK
Thu Sep 13 2018, 08:39 PM
First of all, by reading your reply, I abandoned m...
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Posted By DrNossberg
Thu Sep 13 2018, 03:49 PM
Hi, thanks you for your reply ^^ First of all, by ...
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Posted By ExperimenterUK
Wed Sep 12 2018, 12:12 AM
HiThere are several issues here.The original 8051 ...
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Posted By DrNossberg
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Hello everybody!First of all let me explain some s...
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Posted By ExperimenterUK
Fri Sep 07 2018, 05:08 AM
The compiler thinks the micro doesn't have enough...
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Posted By Sudhansudeep
Fri Sep 07 2018, 02:59 AM
this is the build output message
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Fri Sep 07 2018, 01:38 AM
Change the mobile number as [number removed] in t...
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Posted By ExperimenterUK
Thu Sep 06 2018, 08:56 PM
I don't know what the problem is, I get no errors....
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Posted By Sudhansudeep
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the code is Attachment ...
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Posted By Sudhansudeep
Thu Sep 06 2018, 12:48 PM
the code is same as u sent me for 16 chars