Migrate from 16F628 to 16F628A

[Melanie]

But are you using it with the PIC set to INTERNAL OSCILLATOR?

[Jerson]

Melanie

Yes, I always use the internal osc. No problems yet.

Jerson

[Melanie]

Then you have been very lucky so far.

The Internal Oscillator is rarely on-frequency, it drifts with temperature and has the stability of a political manifesto at election time. The higher the baud rate, the greater the error margin. If you send or receive a short burst, the few bytes might be within spec, but thereafter you will drift out of specification and communication will be corrupted.

The rule is always to use a Resonator or Xtal when doing timing critical functions.

[Jerson]

Hi Melanie

Well, lucky perhaps. But, the most times, I have used the Serout / Serin functions as a handshake and they carry very little traffic. My products usually power off to a sleeping state which is around 90-95% of their working time. So, perhaps this is where I am lucky.

I can see your point about the internal oscillator drifting with time and temperature; and will keep it at the back of my mind for projects involving longer running times for serial communications.

Hey, btw : I like your analogy about the election manifesto. Looks like none of 'em politicians have reached me yet

Cheers
Jerson

[cooksydesign]

Well, that worked. Thanks. I have to attach resonators to SSOP packages. Quite a few of them.

One more question, please;
The package type is a 16LF628A. Data sheet says it will operate at 2.5 volts. What do I need to do to get it to run on the low voltage? I have a 3 volt regulator in the circuit, and it does not run. At all. Even blinking a LED.

Thanks again.

B

[Ingvar]

Make sure brownout reset in not enabled.

[cooksydesign]

Thanks, disabling Brown-out Reset did the trick. I thought I had tried every combination to get the darn thing to run. Thanks.

Is it possible to use the 3v regulator when using the ICP? Presently I have to disconnect the 3v to the uC, connect 5v and burn the chip.

Otherwise, other than the mess I have soldering a resonator onto the SSOP, I'm in much better shape than I was 4 hours ago.

Brad