> The source I sent is the actual operational source for my programmer,
> which can definitely erase a code protected 16F877.  Are the Vpp and Vdd
> voltages within spec.  Note that the allowable Vdd range is narrower for
> erasing and programming the chip than for verifying it.  If I remember
> right, Vpp needs to be 13V +-.5 and Vdd 5V +-.5.  I would want to be
> closer than +-.5V.

I'm using a low voltage programmer, so Vpp = Vdd = 5.25V.  The 16f87x memory programming
datasheet (DS39025F) doesn't explicitly state that LVP mode is able to do a code
protected bulk erase, however it does say that other than the lower Vpp voltage and
dedicating RB3 to programming, "All other specifications for high voltage ICSP apply".

I'm beginning to think that maybe the code protected bulk erase needs Vpp at the high
voltage level (Vdd + 3.5) rather than the low voltage level (Vdd) as provided by my
programmer.  I'm going to modify my TLVP to use a higher Vpp (make it a THVP) and see if
that solves the problem.  Have you (or anyone else for that matter) found any
documentation that says LVP mode can or can't do this kind of erase?

Sean

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