Lee Jones wrote:
> It is obvious ... once you know about it.  PIC 18F2220/2320/4220/4320
> data sheet, DS39599C, section 6.6 "Flash Program Operation During
> Code Protection" has 1 sentence refering you to section 23.0 (with
> a note to see 23.5 "Program Verification And Code Protection")."
>
> No where in section 23.5 "Program Verification And Code Protection"
> does it mention the 4.5V to 5.5V requirement to erase the chip.
>
> You have to read to section 23.9 "Low Voltage ICSP Programming"!
> The last sentence of that section finally mentions the restriction.
> Tucked into the regular text, with no highlighting or emphasis, are
> two sentences addressing this.  And the important one, stating the
> PIC needs 4.5V to 5.5V to do a block erase, is almost misleading
> because it qualifies it with "when using low voltage programming".
> In fact, bulk erase ALWAYS needs 4.5V to 5.5V, no matter which
> programming mode you are using.

I don't remember if I've looked at that specific programming spec, but for
the ones I have seen they show the min/max Vdd levels for bulk erase in the
electrical specifications table near the end, which seems like a reasonable
place for voltage level issues.  Someone designing a circuit for ICSP might
not read most of the algorithm descriptions, but would certainly look thru
the electrical specifications.


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