Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

PIC16F84 and PIC16F84A

Status
Not open for further replies.

andy257

Member
Hi All,

does anyone know the difference between the two devices?

I assume the PIC16F84A is a direct replacement for the PIC16F84 but in MPLAB there are options to select either device.

Can anyone clear this matter up?

Also would it be possible to port over the code wrote for one pic into the other? "84"-"84A"

Cheers

Andy
 
Hi,
they aren't very different.for example PIC16F84 clock input is from DC to 10MHZ but PIC16F84A clock input is from DC to 20MHZ.in MPLAB you should choose PIC16F84A if you use this microcontroller.
 
Last edited:
hey there,

for all intents and purposes they are essentially the same chip, mainly, as has already been pointed out, the clock circuitry was revised, along with a few other little tweaks internally. Code writen for one, will run ok on the other, unless you are specifically wanting to use the extra clock speed for something. Below 10Mhz, applications should run equally well with either chip, assuming that you are using the 10Mhz version and not the 4Mhz version of course.
I seem to remember there being a slight difference also in programming spec, but it's probably a timing thing, most of the homebrew style programmers won't have an issue with it though, I don't think, because their tolerances are pretty wide. My Superpro programmer for instance, demands the correct chip be selected before it will begin to program it, but it has a smidge tighter tolerance than the average simple pic/eeprom only style programmers.

hope this helps...
 
The 16F84A is a 'later silicon revision', that's all, it's a direct source code replacement for the 84, but has slightly different programming requirements.

But in any case, both are long obselete, you should use the 16F628 which replaced the 84A last century! - there are a couple of VERY minor chnages you have to make to your code, but they really are trivial!.
 
Nigel Goodwin said:
The 16F84A is a 'later silicon revision', that's all, it's a direct source code replacement for the 84, but has slightly different programming requirements.

But in any case, both are long obselete, you should use the 16F628 which replaced the 84A last century! - there are a couple of VERY minor chnages you have to make to your code, but they really are trivial!.

The only reason i am using this chip is my university has used it for many years for teaching the microcontrollers module. Its excellent for beginners. I wanted to be able to program at home as well as uni so looked into buying a programmer and chip. However i couldnt find anywehre that did the 16f84 only the 16f84A was available as a sample from microchip.

Cheers

Andy
 
Like I said, buy the 16F628, it's cheaper and a higher spec, no one should be buying the 16F84A these days - the only changes to the code required are the start address of the GPR's (I think? - it's been so long I can't remember?), plus add two lines of code to disable the 16F628 analogue comparators - it's really that simple. There used to be a migration document you could download at MicroChip, but it's so long ago (perhaps 8 or 9 years?) I don't think it's there any more?.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top