16LF devices (low voltage)

[Eugeneo]

I can't find any specs on programming the 16LF819 chip. Can VDD be 5v when programming this devices? Is the LVP bit set low at the factory?

Does anyone know where the datasheets are... I have the chip so it does exist

[asmallri]

The data is combined in the standard PIC16F819 datsheet. The PIC16LF819 can be programmed with VDD at 5 volts. The LVP has nothing to do with the low voltage operation of the chip. It means that it can be programmed without the MCLR pin being raised to +12volts. This is the same for all current generation PICs.

LVP is (short sightedly, disasterously and stupidly) enabled by default :-)

You must specifically disable it by setting the NOLVP fuse.
_________________
Regards, Andrew

http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!!

[Eugeneo]

Ok... I've checked and re-checked everything the chip accepts 5 volts but when MCLR goes to 12volts, the chip gets warm.

I haven't made any modifications to the wiring since I first put it into program mode.

It just doesn't seem to work

[Eugeneo]

The programming data sheet has no reference to the LF device. So I assumed it could be programmed in NOT LVP mode with VDD being 5V ... am I wrong to asssume this?

[Eugeneo]

I'm beginning to think the LVP is enabled as a default, because the LF devices cannot be programmed in NON LVP mode. Could this be true?

[asmallri]

LVP IS DEFINITELY ENABLED BY DEFAULT - hence my comments.

Are you sure your circuit is not enabling LVP RB3 (pin 9) by letting it float or pulling it high before you have programmed the PIC initially?

If your chip is getting hot with +12v on the MCLR pin then you probably have a wiring error. Is the diode correctly installed between VDD and MCLR?
_________________
Regards, Andrew

http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!!

[Eugeneo]

I checked the connections again and they are right. I viewed them on a scope and MCLR is definitly at 13 volts +-.2

Does anybody have the programming specifications for the LF device?

[asmallri]

When MCLR is at 13 volts - what is the voltage on VDD?

Also look at the datasheet for the 16F819 and search for LVP. It tells you where to find the programming specification.
_________________
Regards, Andrew

http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!!

[Eugeneo]

When MCLR is at 13 volts VDD is 4.98

[Eugeneo]