Programming problems with low-voltage PIC18LF452

[Tyler Coen]

Hi,
Has anyone experienced difficulty programming PIC18LF452 devices when operating at 3.3V?

I have an adapter to a PICStart plus that connects the ICSP lines to my PCB. The setup works fine when programming parts that are powered to 5V. However, I cannot program parts powered to 3.3V. There are no hardware errors.

I suspect it may have to do with block erase cycles. The PIC18F452 datasheet (pg.270) says these operations can only be done at 5V. However, it says all other ICSP operations can be performed at the regular operating voltage.

Does anyone have any experiences, insights or solutions to this problem? Any help is appreciated.
Thanks
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This message was ported from CCS's old forum
Original Post ID: 144516376

[jpt@tayloredge.com]

The bulk erase is where the problem is on the flash parts. It is not spec'd to work at less than 4.5vdc. If you bulk erase at say 3.3V, it looks like it did it but then odd behaviour ensues, including configuration bit problems. I have found that MPLAB, working at 3vdc and "Erase all before program" turned off works fine. If you ever do a bulk erase by accident at 3v however, the only way to recover that part is to raise vdd to 5v and bulk erase. (A byte erase + write mode will not work at 3v until you have done so!!!!)

I'm not sure how PCWH handles the process, not having programmed at <5v with that tool yet!
___________________________
This message was ported from CCS's old forum
Original Post ID: 144516451

[jpt@tayloredge.com]

The bulk erase is where the problem is on the flash parts. It is not spec'd to work at less than 4.5vdc. If you bulk erase at say 3.3V, it looks like it did it but then odd behaviour ensues, including configuration bit problems. I have found that MPLAB, working at 3vdc and "Erase all before program" turned off works fine. If you ever do a bulk erase by accident at 3v however, the only way to recover that part is to raise vdd to 5v and bulk erase. (A byte erase + write mode will not work at 3v until you have done so!!!!)

I'm not sure how PCWH handles the process, not having programmed at <5v with that tool yet!
___________________________
This message was ported from CCS's old forum
Original Post ID: 144516455

[IK1WVQ]

:=Hi,
:=Has anyone experienced difficulty programming PIC18LF452 devices when operating at 3.3V?
:=
:=I have an adapter to a PICStart plus that connects the ICSP lines to my PCB. The setup works fine when programming parts that are powered to 5V. However, I cannot program parts powered to 3.3V. There are no hardware errors.
:=
:=I suspect it may have to do with block erase cycles. The PIC18F452 datasheet (pg.270) says these operations can only be done at 5V. However, it says all other ICSP operations can be performed at the regular operating voltage.
:=
:=Does anyone have any experiences, insights or solutions to this problem? Any help is appreciated.
:=Thanks

hi,
i use a bootloader with 18lf8720 at 3.3V without any problem..
my bootloader dont perform a "bulk erase", off course, but
simply a page erase...

regards ..
___________________________
This message was ported from CCS's old forum
Original Post ID: 144516556