PIC programming hardware Vpp values

[ljcox]

PIC programming hardware - Vpp values

I recently discovered - by looking at some of the files in the MPLAB IDE Device folder (see Program Files (x86)\Microchip\MPLAB IDE\Device) - that the nominal programming voltage (Vpp) is not always 13 Volt. Some examples (taken from the respective .dev files) are shown below - note that the PICs 16F684 & 16F917 are 11 Volt nominal with a maximum of 12 Volt!

PIC16F84
vpp (range=12.000-14.000 dflt=13.000)

PIC16F88
vpp (range=12.500-13.500 dflt=13.000)

PIC12F675
vpp (range=12.750-13.250 dflt=13.000)

PIC16F684
vpp (range=10.000-12.000 dflt=11.000)

PIC16F917
vpp (range=10.000-12.000 dflt=11.000)

All of the PIC programming hardware I have seen were designed to apply about 13 Volt. So I don’t know what would happen if one of these was used to programme a 16F684 or a 16F917. But I don't intend to find out!

I recently purchased three of the 16F684 PICs but have not programmed any of them yet. So I will modify one of my programmers so I can switch it between 11 and 13 Volt using a jumper shunt.

One of the programmers I constructed is the dSPIC/PIC Programmer published by Silicon Chip in their May 2008 issue. This one covers a wide range of PICs & it will be easy to modify. So I will do it in the new year and post the details in this forum.

 

[betwixt]

Microchips own PICkit devices have programmable VPP and select the correct voltage according to the PIC chosen.

Brian.

 

[ljcox]

Microchips own PICkit devices have programmable VPP and select the correct voltage according to the PIC chosen.

Brian.

Thanks Brian,
I assumed that was the case. They want us to buy PICkits.
Len

 

[betwixt]

More a case of the clones sacrificing functionality to make them cheaper.

The PicKits use a programmable boost converter so any voltage up to about 15V can be produced in small increments but most clones are either fixed or in some cases use unregulated voltage from a serial port (typically about 11V). It is out of specification but works most of the time.

Brian.

 

[ljcox]

Thanks Brian.