In Chip Serial Programming (ICSP) Advice

[Steve001]

Afternoon All,

Bit confused looking to put a header so that i can connect a picckit 3 to my project and do updates if required. or when i change my mind on how it works.

Looking at the data sheet and a guide from microchip was not sure so i looked at the EB006-9 programmer as this works.

Can i ask .. diode D2

why is it fitted ?
what is it doing ?
is there any special characteristics required if i need to add one ?
would a BAT85 be ok or is the volt drop too high?

http://uk.farnell.com/nexperia/bat85-11 ... dp/1097299

as the ICSP guide says not to fit diodes as MCLR needs to be controlled via the pickit device

do i need to remove the 5 volts from the rest of the connected equipment whilst programming ? as i don't do this with my eblocks or is their some "wizardry" going on, on the programmer board that mimics this ?

do i chuck the ICSP guide away as not relevant to my device ?

i am looking at using a PIC16F18875

Steve

[EtsDriver]

why is it fitted ?
what is it doing ?
is there any special characteristics required if i need to add one ?
would a BAT85 be ok or is the volt drop too high?

I think it is fitted there to prevent high voltage programming mode supplied reset signal (10-12.7V?) entering the +5v rail...

Ive just used 1n4007/4004 equivalent in place of that just to prevent ugly toasted chips in case someone plugs icd3 there or mplab pm3 and uses hvp mode...

Usually seen it in use when chip clocksettings or similar are totally wrong and lvp mode won't find chip.

You don't need to remove supplied 5v as pickit detects extrenal voltage and automatically switches its own supply off. The pickit will be able to pull down/up the reset if your pull-up resistor is high value enough (10-20k).

[Steve001]

After a bit of looking around microchips web site on the matter.
There is a raft of information and some of it is somewhat cryptic and conflicting do this - don't do this.
I found this info sheet that seams quite helpful.

I know it is for a PM3 but this was found in a link on the PICKIT3 technical docs bit

Steve