How to config 18LF2620 to work at 3.3v?

[edysan]

Hello !

I have an 18LF2620 which works correct at 5v, but don't work at 3.3v

I don't use any fuse configuration on my program, and the *.inc is original.

I use MPASM v5.20, and pbp 2.5

Some body can help me to do the right config?

[Darrel Taylor]

What frequency is the main oscillator running at?

4Mhz will get you down to 2.0V, but at 40Mhz you have to stay above 4.2V
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[edysan]

I working with 20 MHz resonator.

[Darrel Taylor]

> I don't use any fuse configuration on my program, and the *.inc is original.
> I use MPASM v5.20, and pbp 2.5
> I working with 20 MHz resonator.

PBP 2.50 defaults to the XT oscillator for the 18LF2620.
At 20Mhz you would need the HS oscillator.

If you have not used any configs, and the .inc is original, I don't see how it could work at 5V either.

According to the datasheet, you can go down to 3.0V with a 20Mhz OSC. So that's probably not the problem.

The only other configs that could affect the operation at low voltage is the Brown Out Detecter. But it defaults to 2V. So I don't think that's it either.
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[edysan]

I have try with:
@ DEVICE BOD_OFF
but don't work.

Have you an correct sample?
May be I will need to rewrite some other times the PIC.
It's right to set LVP_ON?

[Darrel Taylor]

Again. You need the HS oscillator.

I have try with:
@ DEVICE BOD_OFF
but don't work.

Since you are using an 18F, you must be using MPASM as the assembler, and MPASM uses __CONFIG instead of DEVICE.

You should probably read this thread.

Presetting Configuration Fuses (PIC Defines) into your Program
http://www.picbasic.co.uk/forum/showthread.php?t=543

It's right to set LVP_ON?

NO! Bad idea, unless you have a special programmer.
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