programs that previously worked with 16f84 do not work with 16f84A

[jamie_law]

i have a problem i am wondering you can help me with. i just updated my PIC ICs from 16F84 to 16F84A devices - all programs that previously worked with 16f84 do not work with 'A'.

here are my environment specifics:

Software:
--------------
epic programmer version 1.41
- Device 8X
- ROM Size 1K
- OSC LP
- Watchdog OFF
- Code Protect OFF
- Power up Timer ON


PicBasic Pro Compiler 2.40 (all default, handled by CodeDesigner Lite)


CodeDesigner Lite Version 1.5 Build: 5
- 16f84A-04/p is set as PIC type


Hardware:
--------------
16c84 'low cost' printer port programmer.


PIC:
--------
old PIC (previously ran all my programs) 16f84-04/p
new PIC (doesn't run any of these programs) 16f84A-04/p


notes:
--------

in epic, after erasing then attempting to program 16f84A-04/p pics, epic states that the pic is not blank. even after erasing pic and checking straight away if it is blank!

i have scoured the data sheets for an explanation, but have found none.

any thoughts? i am guessing epic and/or the programmer are not up to the job. any help greatly appreciated

Jamie

[Ingvar]

It sounds like your Epic and/or software needs a checkup. Try downloading the latest software at .....

http://www.melabs.com/downloads/E243BET3.ZIP

Also make sure your powersupply is "juicy" enough, atleast 16V during programming without dips. If you're unsure try using two 9V batteries. "Modern" pics is more demanding regarding the programmingvoltage.

Finally(if you're really desperate) you could check the two resistors that connects RB6&7 to Vcc, you can lower them to 1k(if not done already).

There are lots of troubleshooting info about the Epic here....

http://www.melabs.com/products/epic.htm

Good luck
/Ingvar

[jamie_law]

I have downloaded the new Epic and ramped up the supply voltage on my programmer a little. the PIC is behaving itself :erfectly:: - all of my software runs correctly now. Thank you very, very much for this advice.

Regards,

Jamie

[Ingvar]

Good for you.

/Ingvar