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"Locked out 887's"

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LightDiodeDesigns

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Familiarly, when I now push power onto (2!) pics, they automatically run, no matter what I do with VPP!! I recognise this from JDM programming PIC16's, where the chip uses intOSC, and is set to use VPP as a digital input... Basically now I can't reprogram the thing because it is busy running the last PWM routine and won't talk to my MCD, or new PICKIT3...!!!

I know not to set the 2 settings together, MPLAB normally warns, but I had a new PICKIT3 (superb!!!) come this week and wanted to try the PushToProgram feature... I suspect I've done it on a blank chip and its left the config words as they were originally, but can't expain otherwise... "VPP before VDD" seems to make no difference, and even pushing 12v onto VPP won't stop the thing from playing.!! Normally I'd set it to use the external crystal, easy enough to short to get around the problem, but, I think I'm just "locked out" the same as the 2 or 3 16f628's I originally discovered the problem on!!

They're cheap enough, but I hate to throw away a chip, any suggestions, or anyone else found the same? I know my midrange PICs and am gutted, the first chip I've lost in months, RIP!

<hr/>
We love the whole world of electronics!
[ADVERTISING REMOVED] NEAL
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wp100

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Hi,

How have you got Mlcre wired up ?

Is your Digital Input circuitry draining Vpp, have you use a blocking diode in its circuitry ? ( assuming its in circuit)

Have used many chips with Mclre=Off and with a digital input and they reprogram without any problem, the only exception was once having trouble with a 628A. If I remember correctly think doing just an Erase got things working.
 

LightDiodeDesigns

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I wonder if I've blasted the VPP pin with 24v by accident or something, it just does nothing! I know not to set the config, but I've been testing the PICKIT3's programmer to go buttton "coincidentally" and wonder if I have done something in there!
Spooky, I've got about 6 628A's that I still hope to get back into one day!!
Cool, thanks,
NEAL
 

wp100

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Hi,

I wonder if I've blasted the VPP pin with 24v by accident or something,

24v ! How ..??

I know not to set the config,

Why - can you expand ? I always reprogram with the full config info in the code, use the int osc most of the time

I've been testing the PICKIT3's programmer

Be interested to hear how you get on with it -some say its fine, others say the software is so problematic - still .... have the PK2 myself



Have you tried this little workaround on your chips

The workaround (as you have discovered) is to set the clock source switch temporarily to RC while programming the device.
 

LightDiodeDesigns

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Unfortunately I can't get in to set the Config Oscilator-source, RC, HS, it just will not change!! I know the feeling from many 628's

The "24v" might have come from the LED lighting power-side I am writing the driving for in an error-full manor, like I've just dinked the wire or something. My only explanation would be that there's been too much current through VPP and it has "fused" its ground-side and etc! Just like the *flaming* 628s, it is just stuck in time now! VPP before VPP doesn't affect things, nothing I do to VPP (+, 0, - , 12?)will stop the chip flying on its own. I've tried reading the config words but with no luck, but I can imagine what it says but I definately didn't set it myself . I've some 877A's that'l drop in and be a "bit lamer" but still ok.

I wonder if the PICKIT PushToGo has anything to do with anything or if that is incidental. A blur of Neal is all I can play back memory wise, I couldn't get push to go working withiout the USB powering the programmer (strange I am sure) and was playing with that at the time, unless it wouldn't program because it was stuck maybe...

Not the biggest problem on earth but I am disapointed to have done it... At least I have a test-chip that is just PWMing 1/32, 1/16 up to 1/2 on 32 pins, it'll get used poor thing:-|
NEAL
I was OK until I needed it to work, and then something had to go wrong (or it wouldn't be NealWork) I've been to demo the PWM BIG LED controller concept it was in at its destination today (The UK space centre) for an 8 1/2A & 24 30mA controller lighting a model of the InternationalSpaceStation I have been honoured to join-in-abit! I've plenty of 877a's so no panic but the extra codespace would have been handy.
 

LightDiodeDesigns

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Basically this board extended with NPN's and 2803's is controlling a lot of lumens, lots of fun
BlownPic.JPG
Not the best thing on earth, but nor am I! :)
Neal (We love the world!)
 

Kurenai_ryu

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are you sure that you set 12V in vpp when VDD is 0V?? and after that you set VDD to 5V??? (without lowering vpp)

if so, yes your pic just has been burned. better to watch out next time....
 

LightDiodeDesigns

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Yeah, I worked out VPPb4VDD on my MCD2 demo2 setup, to get it to work the board has to be powered from the MCD, that fooled me for a bit... Incidentally with 16F88's I found that popping out the chip and shoving it in that corner 1st made "everything apples", one of those "try everything" moments, but that was with the PIC powered from my Nokia charger... Making the MCD power the circuit I could see the power LED working sheme and it did just as expected, VPP before VDD... I think the chip is killed, and icidentally on the same night I was testing some inductance in the driver chain of some 7w LEDs, and also incidentally using my newly opened PICKIT3 (Absolutely Superb!)

To be honest, for the work, I recon an 18F4865 will make a better replacement. The 16Mhz crystal can be PLL'd and bigger space etc, hmmm, thats PICs for ya, always a test!! :) I had trouble getting the PICKIT3 to Push-To-Go program without powering it from USB, but do I risk lockout on another chip? Yeah, spose so!

Cool XD
NEAL

Thanks indeed, I'll let you know if anything happens, I'll add it to the 6 16F628's and 88's and 877A's that I think are blown but get tested everytime I'm short of one, I throw nothing away!
 

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