Tony Nixon wrote:

> ...Just when you think you are getting on top of the new chips and what
> appears to be a new programming algorithm for each...


Hi Tony,

Take a look at the PIC18FX410/X490 programming specification -- this caught
me off guard.

If the programming specification document for the PIC18FX410/X490 flash
PICmicros is totally correct, then the electrical characteristics have been
changed for this particular group of PIC18F devices (I have not totally
reviewed the programming algorithm yet) versus what seemed to be the norm
for all other PIC18F devices.

I have an e-mail into Microchip on this one just to confirm this:

 * High-Voltage Programming Voltage on MCLR/VPP has been narrowed: 10 to 12
volts WRTG (with respect to ground).
   (all other PIC18Fs: 9 to 13.25 volts WRTG)

 * Programming Current on MCLR/VPP: 100 milliamps
   (I hope they meant microamps as most others were around 300 microamps)

 * Supply Voltage During Programming [CHIP ERASE] lowered: min = 2.75 V WRTG
   (Excellent news if this really means a minimum of 4.5 V is not needed for
a complete bulk erase)

This really seems to drive home the point for me that any PICmicro
programmer really needs a variable Vpp supply under firmware control in
order to be one step ahead of the specifications: inexpensive digital pot
and adjustable LDO regulator.

Best regards,

Ken Pergola

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