Elegant "in circuit programming"

[Ted's]

Is there a schematic for elegant "in circuit programming" being adaptable to several pics?

Elegant meaning:

- you have a modern plug and socket, like usb. As soon as you plug the usb-plug into the socket of the device, all other device's connections that could interfere are blocked electrically. So you plug it in, transfer your program, remove the plug and as soon as the device has voltage applied to it, the "in circuit programming" circuit is blocked and the pic can do it's work.

[bcd]

How about a 4 pole minijack like the ones Sony use to get audio and video out of a camcorder.
Use the break contacts to disconnect the circuit with the jack handling MCLR, PGM, PGC and Gnd.

Might work - need to power you circuit from somewhere though. Hmm - maybe I didn't think that through very well.....

I just use a 5 way SIP header and a couple or resistors and a diode to stop 12v going back into V+ from MCLR line.

bill.

[Ted's]

One should use at least mosfets, opto-couplers or transistors to electrically protect the circuit from the programming circuit.

[bcd]

I tend to design things so I have LEDs for status on the pins that are used for ICSP CLK and DATA lines. This way I can also see that the ICSP is being programmed.

The MCLR lines are normally tied to +5 using a schottky diode with the MCLR from the ICSP to the Processor side of the diode. This prevents 12v from getting back to the 5v side.
Microchip has some ICSP app notes where they use a resistor for MCLR isolation, but it doesn't feel right to me to do it that way..

I also have a diode to isolate the +5v supply to the pic so it can be powered by the programmer, but the programmed doesn't power up the whole board. On a few designs where I know there is not much on the 5v rail I will normally just tied the ICSP 5V to the PIC 5v. I don't tend to have the board powered when programming other than through the ICSP port.

I use a PicKit2 for all my ICSP work and it can provide power to the circuit with control independant of the programming functions. A very handy feature.

[Ted's]

Do you also agree that you misunderstood me?

[bcd]

I'll agree that something is getting lost somewhere - what exactly have I missed ??

bill.

[Acetronics2]

Is there a schematic for elegant "in circuit programming" being adaptable to several pics?

Elegant meaning:

- you have a modern plug and socket, like usb. As soon as you plug the usb-plug into the socket of the device, all other device's connections that could interfere are blocked electrically. So you plug it in, transfer your program, remove the plug and as soon as the device has voltage applied to it, the "in circuit programming" circuit is blocked and the pic can do it's work.

Hi, Ted's

I think I already have some kind of that on my Mikroelektronika EasyPic 5 ....

Just paste it !!!

All the doc. is downloadable from their site ...


BTW, your idea Also has a strange taste of ... Bootloader !!! don't you think ???


Alain - Hot water future discoverer.



PS: Question for a Very High School exam : ( serious joke ! )

Q : How do you proceed for making tea ???

A: I take a water pan, let it boil , place the tea leaves into the tea-egg, drop the egg in the water, let it a moment in and serve ...


Q: Ok ... fine. Now, suppose you already have boiling Water ... how do you proceed ???

A: Quite simple: I let the water cool , ... then go back to the previous problem.

Q: ....