Erased and protected PIC

[Joel Rainville]

I am pretty sure I have accidentaly programmed a PIC16F876A with all 0x00 : program memory, config bits, EEPROM, everything!...

A config fuse of 0x0000 for the 16F876A gives :

Flash Program Write : 0h to FFFh write Protected
Data EE Read Protect : On
Code Protect : On

I'm screwed, right?

If it is read protected, should I really be unable to read *anything* off the chip?

I use an ICD2 clone to program with MPLAB. That ICD2 is running fine. I can read other 876As or any other PIC just fine with it...

When I hit "connect" in the "programmer" (or "debugger", doesn't matter) menu, MPLAB doesn't even recognize the chip as a 876A :

Invalid target device id (expected=0x70, read=0x0)

Read protected or toast?

 

[Exo]

i dunno about ICD2, but if you have a P16Pro40 with winpicprog you could just erase the device and it would be ok again...

 

[Mike - K8LH]

I may be wrong, but, I would think you'd still be able to read the Device ID from a write protected chip... Let me dig out the Data Sheet and the Programming Spec and get back to you...

Regards, Mike

 

[Jay.slovak]

I may be wrong, but, I would think you'd still be able to read the Device ID from a write protected chip... Let me dig out the Data Sheet and the Programming Spec and get back to you...

Regards, Mike

Yes, you still can read device ID while it's protected. I think that the connection between the PIC and ICD2 is not OK or the PIC is damaged. :evil:

 

[Mike - K8LH]

Yes, you still can read device ID while it's protected. I think that the connection between the PIC and ICD2 is not OK or the PIC is damaged.

That's what I thought Jay... I have a product using a code protected 12F683 and I can read the Device ID and reprogram that without problem but I have not tested the same on a 16F876A...

Since he can read and write other devices with his ICD2, I suspect this one 16F876A may be defective...

Regards, Mike

 

[Jay.slovak]

Yes, you still can read device ID while it's protected. I think that the connection between the PIC and ICD2 is not OK or the PIC is damaged.

That's what I thought Jay... I have a product using a code protected 12F683 and I can read and reprogram that without problem but I have not tested the same on a 16F876A...

Since he can read and write other devices with his ICD2, I suspect this one 16F876A may be defective...

Regards, Mike

Yes I agree. I had simmilar problem with two 18F4320 until I found out they were damaged. :cry:

 

[Joel Rainville]

Let me dig out the Data Sheet and the Programming Spec and get back to you...

The datasheet doesn't seem to mention anything related to the ability to read the device ID of a protected PIC. But let me know if you find something interesting!...

I am now convinced it is damaged. What to do with a broken PIC? Art? Jewelry? Put tiny wheels on it? Will it float on coffee? Can it physically survive a full cycle in the dryer? :twisted:

Ok, time for a break... :roll: :lol:

 

[Mike - K8LH]

What to do with a broken PIC?

Gosh, I don't know... I've only ever destroyed one PIC before (thank goodness)... 'Twas an 18F4320 that I was using for my first adventure with unipolar stepper motors... Originally the 5v steppers were connected to the regulated 5v rail along with the 18F4320 but I soon realized the steppers needed much more current so I added a couple 5w current limiting resistor in series with the stepper common windings and moved the 5v rail over onto the 12v rail, along with the 18F4320 (Doh!)... I just tossed the blown-up '4320...

Regards, Mike

 

[eblc1388]

What to do with dead PIC? I loved the comment by one of the posters "to place it upside down in the bathroom, but you have to make sure the pins are lead free to start with.".

I had simmilar problem with two 18F4320 until I found out they were damaged. :cry:

Do you remember why they are damaged, on what external circuit?

Did you exceed any maximum datasheet rating or the cause of death unknown?

 

[Jay.slovak]

Well, I killed one when I was building one power supply. It had different PCBs (CPU board, LCD board, POWER board,COM board) and I didn't connect ground between CPU and POWER board (POWER board has own +28V source as a voltage reference, and it's 5V are powered from CPU board) and it somehow destroyed the PIC :x
And the second PIC died of unknown reason, probably because od ESD (I had it lieing on my table for a while).
I also fried one 16F628 (when I was a newbie) because of it's internal comparators so I used +12V as Logic 1 (stupid me). The PIC still "works" but I can't reprogram it :evil:

 

[eblc1388]

Hi Jay,

Thanks for sharing the unpleasant experience.

Rather than consider that stupid, I think that's a normal learning process. The important point is to understand why such action would damage something and never do that again.

 

[Jay.slovak]

No problem, I guarantee you I won't destroy more PICs like that. I have learned a valuable lesson.

 

[samcheetah]

What to do with a broken PIC?

Gosh, I don't know... I've only ever destroyed one PIC before (thank goodness)... 'Twas an 18F4320 that I was using for my first adventure with unipolar stepper motors... Originally the 5v steppers were connected to the regulated 5v rail along with the 18F4320 but I soon realized the steppers needed much more current so I added a couple 5w current limiting resistor in series with the stepper common windings and moved the 5v rail over onto the 12v rail, along with the 18F4320 (Doh!)... I just tossed the blown-up '4320...

Regards, Mike

you actually drived a stepper directly with a PIC. and there were no driving transistors right?? wow :lol:

did the PIC blow up into pieces? if it did then i think i have a bit of work to do on this weekend :twisted:

 

[Someone Electro]

Well i sucseded to blow up an 555 timer the was fryed by a backwards power suply.

I have an cuple of transformers laying around and one that outputs 20V at 10A was perfect.So i conected to whole left row to one output and the right row of pins to the other.Then i pluged it in an in about 2 seconds: POP and the IC literaly smoked.It made lots of white smoke.I sudenly puled out the plug and went to exsamine the chip.It was hot ufcurse and the chip was cracked open.

It cod work whith an PIC too.

 

[evandude]

I don't think I've ever found any IC's that are tougher than PICs.

Working on a breadboard, not using ICSP, so pulling the chip every time you program, it's easy to plug it in backwards, which reverses VDD and VSS... Once I couldnt figure out why my circuit wasn't working, I was probing around with a multimeter and everything. Then I looked up at the power supply and it had the overcurrent light on... with the current pegged at 2.5 amps! The PIC was connected that way for a total of about one minute, and it got hot enough to burn my finger when I touched it. And yet, when I flipped it back around, it worked fine. The only time I've ever succeeded in killing a PIC was powering it off 12v accidentally...

 

[Jay.slovak]

PIC are pretty though, usually they can stand hard conditions, but ESD is a killer.

 

[Nigel Goodwin]

Working on a breadboard, not using ICSP, so pulling the chip every time you program, it's easy to plug it in backwards, which reverses VDD and VSS... Once I couldnt figure out why my circuit wasn't working, I was probing around with a multimeter and everything. Then I looked up at the power supply and it had the overcurrent light on... with the current pegged at 2.5 amps! The PIC was connected that way for a total of about one minute, and it got hot enough to burn my finger when I touched it. And yet, when I flipped it back around, it worked fine. The only time I've ever succeeded in killing a PIC was powering it off 12v accidentally...

THAT'S how you get fingerprints on your PIC :lol:

If put in backwards, all the protection diodes are then conductive, directly across the supply - so it's the protection diodes that pass the current and generate the heat.

 

[Exo]

happened to me once too...
But i always use my bench supply , limited at 50mA to test new pic designs (with no other load offcourse)...

 

[Nigel Goodwin]

happened to me once too...
But i always use my bench supply , limited at 50mA to test new pic designs (with no other load offcourse)...

I only use a small 9V battery (Duracell MN1604), and a 7805 or 78L05 (depending what is to hand) - and they still burn fingers :lol:

A 50mA current limited supply is a GOOD idea, but too much trouble compared to a small battery!.

 

[Mike - K8LH]

samcheetah wrote;

you actually drived a stepper directly with a PIC. and there were no driving transistors right?? wow

No I didn't directly drive the stepper motor coils... I used TIP122 Darlingtons... LOL!!!

Regards, Mike