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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.
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One should use at least mosfets, opto-couplers or transistors to electrically protect the circuit from the programming circuit.
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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.
Last edited by bcd; - 29th August 2008 at 00:17. Reason: Spelling mistakes (again..)
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Do you also agree that you misunderstood me?
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I'll agree that something is getting lost somewhere - what exactly have I missed ??
bill.
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Why? However, if you are suggesting using the above components (that's a pretty authoratative statement), maybe you know something we don't, so share with us...One should use at least mosfets, opto-couplers or transistors to electrically protect the circuit from the programming circuit.
In the meantime, do a forum search... it's all been discussed before... and in some threads you'll even find some schematics... eg Post #14 on this thread...
http://www.picbasic.co.uk/forum/showthread.php?t=516
People give you suggestions here, things they use, things that work for them. You can do what works for them, you can take the idea and create something of your own, or you are free to do something completely different. But hey, let's not post a detailed specification and shoot people down when they don't meet it exactly!
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@bcd and @Melanie: My idea is to connect the bases of a series of transistors (or gates of a series of mosfets for that matter) via resistors to vdd of each circuit that should be separated. So a set of 5 items is necessary for each circuitry. So as soon as voltage is applied the right connection is open. I asked myself whether it is better to use a whole chip (which name?) or a series of transistors or mosfets or even opto-couplers. Whereas I do not know whether programming of a pic is partly analogue so opto-couplers might not work.Originally Posted by Melanie
This is exactly what I presume. Every mp3-player must contain a similar circuitry - basically every plug and play device.it's all been discussed before...
That does not deal with the issues occurring when the pins needed for programming are used in the circuitry serving the pic aswell.
Melanie, I am sure you want me to treat you with respect. If so, don't give me advice if not asked for it in general.People give you suggestions here, things they use, things that work for them. You can do what works for them, you can take the idea and create something of your own, or you are free to do something completely different. But hey, let's not post a detailed specification and shoot people down when they don't meet it exactly!
Nice. I like it because in some situations it is the right approach and in others...I let the water cool , ... then go back to the previous problem.
Last edited by Ted's; - 30th August 2008 at 18:29.
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