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Kit128 programmer and ICSP

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qratman

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Hi,

I am using kitsrus kit128 in ICSP mode in simple breadboard playground.
The thing is when idle, kit128 Vcc line is always low. Is that normal?

I have wired it like shown in 16f88 datasheet fig. 15-13 typical icsp connection. Programming lines are dedicated to icsp. I've put 100 ohm from pic to breadboard+. PIC programs fine but doesn't start to run after programming. Removing icsp connector (or just disconneting its Vcc line) makes pic work fine.

Is there any better way instead of disconneting icsp plug everytime after pic programming?
 
Hi,
I was using a Velleman programmer with its ICSP output, I had exactly the same problem, the easiest way is to use a diode (a 1N4148 is fine) from the VPP pin of your ICSP socket to the VPP pin of the Chip.
There should also be a reverse diode via a 1K (ish) resistor up to the VDD line to prevent the VPP voltage passing to VDD.
When the ICSP line goes LOW after programming the chip, the first diode causes the VPP pin to remain at VDD via the second diode from the VDD line.
But when the ICSP pin goes to its programming voltage, (ie nominal 12/13v) the first diode 'passes' the power to the VPP pin as it is above the VDD voltage, so raising it to allow for programming and the second diode prevents this voltage getting through to the VDD supply.
Hope that helps
Roy
 
Nope, in your case ICSP was pulling MCLR low bringing pic to constant reset.
However with my programmer, it doesn't seem to pull MCLR (VPP) low during idle. It pulls PICs power (VCC) low, so PIC can't run at all.

I can move resistor between pic and ICSP but then it won't program correctly, becuase programmer can't control PICs VCC line.

That's strange because I remember, dunno if correctly, having used it before and it worked without connecting-disconnecing anything.
 
i'm using same programmer (k128) and having same problem.I though this is a noraml operation. so i keep on connecting / disconnecting ICSP cable. compared to removing the whole IC, this was much easier way. so far i used it to program 16f628/a. ( N.G. Tutorials )
 
Yes, its easier than fliping between sockets but even easier is not to touch anything at all, just click to program.

As for this being normal. I dont know, I just started using ICSP recently.

So can anyone confirm, is microchip's ICSP programming meant to be able to program chip while it is not running?

I have very briefly used AVRs and their ISP programming doesn't need any hardware side touching before or after programming. Just tell computer to program avr, it programs and after it starts executing fine while ISP cable is still connected.
 
The ICSP cable is used both to program and to debug.

In the program mode you can select Release-From-Reset when using an MPLAB compatiable programmer. This will allow the target to run. Selecting Hold-In-Reset will stop the target. Other good programming software should have a Release and Hold function.

In the debug mode the program is controled using step-into, step-over, and run.

If these programmers are not MPLAB compatiable you may want to look into getting one that is. I suggest either a PICkit2, ICD2, or a clone. If you are on a budget you can build an RS232 based ICD2 for not much more the the cost of the 16F877(A). A PICkit2 is much faster but will cost more. My favorite place to find kits and schematics is https://www.blueroomelectronics.com. Although the main goal is to sell kits you can find working schematics for the Inchworm (ICD2) and Junebug (PICkit2) clones.

HTH
 
Last edited:
Thanks for the info.

It's true, kit128 isn't mplab compatible. I am quietly leaning towards the PICkit2 but for the moment being I am using kit128 with push button between pic and icsp VCC and 100R between PIC VCC pin and board VCC.
This way I only have to hold button down while programming, not remove and insert icsp on and off.
 
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