Post by thread:[PIC]: What's the real deal with code protection?

I read in some places (datasheets, etc) that code protection is a great feature, etc and what is does, etc. Great! However, on other sites, I've read that I should absolutely not use it cause the chip will be forever un-reusable, even if it's erased. Huh??? So what's the real (and lastest) deal here? Is there a problem with a specific PIC or series of PIC's? Is a a non-reliable feature for all PIC's? I'm using the PIC16F84A and PIC16F872 for now, so I mostly concerned about these for now. Cheers, -Neil. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

IIRC, don't think it applies to the flash series. I recall in past documentation that it applies to eeprom window types only. Rick Pic Dude wrote: {Quote hidden}> I read in some places (datasheets, etc) that code protection is a great > feature, etc and what is does, etc. Great! However, on other sites, > I've read that I should absolutely not use it cause the chip will be > forever un-reusable, even if it's erased. Huh??? > > So what's the real (and lastest) deal here? Is there a problem with a > specific PIC or series of PIC's? Is a a non-reliable feature for all PIC's? > I'm using the PIC16F84A and PIC16F872 for now, so I mostly concerned > about these for now. > > Cheers, > -Neil. > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

At 10:31 AM 3/18/02 -0600, Pic Dude wrote: >I read in some places (datasheets, etc) that code protection is a great >feature, etc and what is does, etc. Great! However, on other sites, >I've read that I should absolutely not use it cause the chip will be >forever un-reusable, even if it's erased. Huh??? > >So what's the real (and lastest) deal here? Is there a problem with a >specific PIC or series of PIC's? Is a a non-reliable feature for all PIC's? >I'm using the PIC16F84A and PIC16F872 for now, so I mostly concerned >about these for now. That warning applies to windowed eprom-based PICs ("C" series parts) only. It does NOT apply to flash ("F" series) parts. If the actual part number on the PIC has a "/JW" in it, the warning applies. But you don't even need to look at the part number: if the PIC has a erase window on the top, DON'T enable code protection. dwayne Dwayne Reid <spam_OUTdwaynerTakeThisOuTplanet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 18 years of Engineering Innovation (1984 - 2002) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

The older UV erasable PICs were often not reprogrammable if the code protect was used. Since most of the sites you see are hobbyist related then for hobbyists (who may have spent $20 & S&H for a windowed UV erasable PIC) having a dead pic because of code protect was a bad thing, and often strongly discouraged. The flash chips are always fully eraseable, even with code protect enabled. The older webistes simply have not been updated to reflect that flash chips don't have this 'problem'. -Adam Pic Dude wrote: {Quote hidden}>I read in some places (datasheets, etc) that code protection is a great >feature, etc and what is does, etc. Great! However, on other sites, >I've read that I should absolutely not use it cause the chip will be >forever un-reusable, even if it's erased. Huh??? > >So what's the real (and lastest) deal here? Is there a problem with a >specific PIC or series of PIC's? Is a a non-reliable feature for all PIC's? >I'm using the PIC16F84A and PIC16F872 for now, so I mostly concerned >about these for now. > >Cheers, >-Neil. > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

At 09:44 AM 3/18/02 -0700, you wrote: ("F" series) parts. >If the actual part number on the PIC has a "/JW" in it, the warning >applies. But you don't even need to look at the part number: if the PIC >has a erase window on the top, DON'T enable code protection. .. if you ever want to be able to re-use the chip. In some circumstances you might want to code protect a windowed chip. Say you have only the windowed version and have to ship it NOW to a customer who has not yet paid for the code. The cost differential (only a few dollars) and fast shipping time might be very cheap insurance. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" .....speffKILLspam@spam@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com 9/11 United we Stand -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Code protection is great when a chip is sent out to a client. With a little bit of research, they can easily retrieve all of your code - unless you enable code protect. It's NOT good to enable code protect when you're prototyping. And, theoretically, you COULD still use a windowed chip once code protect is enabled; you simply couldn't reprogram it. However, since windowed chips are usually 2x - 3x the cost of OTP's or flash, I don't know why someone one use a windowed chip in the final product. Just a few useless observations : ) JL -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

At 12:28 PM 3/18/02 -0500, you wrote: >And, theoretically, you COULD still use a windowed chip once code protect is >enabled; you simply couldn't reprogram it. However, since windowed chips >are usually 2x - 3x the cost of OTP's or flash, I don't know why someone one >use a windowed chip in the final product. Some of the 17C series are not that different in very small quantities (15% more in 1-24 pcs. for erasable 33MHz). Erasables are more versatile. >Just a few useless observations : ) Hardly. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" speffKILLspaminterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com 9/11 United we Stand -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

At 11:54 AM 3/18/02 -0600, you wrote: >'Useful' actually. I've been wondering the same thing. My guess is that >the non-windowed versions have become popular enough to drive >prices lower than the windowed versions. I think you'll find that the windowed chip pricing is mostly a "policy" issue and has little to do with mfg. cost. Motorola, for example, exacts a hefty price for their windowed chips, and some such as the PLCC-44 ones are not guaranteed as well as the normal production of OTPs, more like engineering samples. Philips, for some of their OTPs doesn't bother to make windowed version at all (you must buy an emulator and burn OTPs for final checking- but the parts beat out most competitors in their class, so you have to consdier them for quantity production). IIRC, ST charges a fairly hefty fee for their windowed chips. Microchip charges relatively low prices (and as is typical) does not discount for quantity. If anything it would be related to the number of developers using the chips, rather than the total sales of OTP chips. Anyone using them in quantity won't pay much attention to the cost of a few windowed chips. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" .....speffKILLspam.....interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com 9/11 United we Stand -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

I am using a couple of 17C756A (windowed) programing, erasing, programing again, erasing ... and everytime I think it will be tha last version, so I set code protection everytime, and it is allways erased with the program under the UV lamp. Francisco Rick C. wrote: {Quote hidden}>IIRC, don't think it applies to the flash series. I recall in past documentation >that it applies to eeprom window types only. >Rick > >Pic Dude wrote: > >>I read in some places (datasheets, etc) that code protection is a great >>feature, etc and what is does, etc. Great! However, on other sites, >>I've read that I should absolutely not use it cause the chip will be >>forever un-reusable, even if it's erased. Huh??? >> >>So what's the real (and lastest) deal here? Is there a problem with a >>specific PIC or series of PIC's? Is a a non-reliable feature for all PIC's? >>I'm using the PIC16F84A and PIC16F872 for now, so I mostly concerned >>about these for now. >> >>Cheers, >>-Neil. >> >>-- >>http://www.piclist.com hint: PICList Posts must start with ONE topic: >>[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads >> > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Not only are windowed versions more expensive to produce (ceramic package with a quartz window = $$), but they tend to behave erratically when operating in a lighted environment. All the transisters act like little phototransisters. The only case where you'd use one in production is when you want to update the program on it occasionally without the cost of a new OTP chip - such as replacing the picstart+ chip with a windowed version. -Adam Pic Dude wrote: {Quote hidden}>>... However, since windowed chips >>are usually 2x - 3x the cost of OTP's or flash, I don't know why someone >> >one > >>use a windowed chip in the final product. >> >>Just a few useless observations : ) >> > >'Useful' actually. I've been wondering the same thing. My guess is that >the non-windowed versions have become popular enough to drive >prices lower than the windowed versions. > > > >{Original Message removed}

Some of the chips do not have the 'feature' of a non-erasable code protect word. It was added (so we have speculated on this list long ago) to prevent a hacker from using a UV laser beam to erase only the code protect word (which was, long ago, kept physically seperate from the rom area of the chip). It is physically realized as an extra layer of UV resistant material on top of the code word. Some chips will erase it with increased exposure to UV (several hours, several days, several weeks), others have reported being able to place them in the oven at a temperature out of spec. But many of the older chips were never changed. You can find a list of windowed chips which have this 'feature' with some programmers' documentation. -Adam Francisco Ares wrote: {Quote hidden}> I am using a couple of 17C756A (windowed) programing, erasing, > programing again, erasing ... and everytime I think it will be tha last > version, so I set code protection everytime, and it is allways erased > with the program under the UV lamp. > > Francisco > > > Rick C. wrote: > >> IIRC, don't think it applies to the flash series. I recall in past >> documentation >> that it applies to eeprom window types only. >> Rick >> >> Pic Dude wrote: >> >>> I read in some places (datasheets, etc) that code protection is a great >>> feature, etc and what is does, etc. Great! However, on other sites, >>> I've read that I should absolutely not use it cause the chip will be >>> forever un-reusable, even if it's erased. Huh??? >>> >>> So what's the real (and lastest) deal here? Is there a problem with a >>> specific PIC or series of PIC's? Is a a non-reliable feature for >>> all PIC's? >>> I'm using the PIC16F84A and PIC16F872 for now, so I mostly concerned >>> about these for now. >>> >>> Cheers, >>> -Neil. >>> >>> -- >>> http://www.piclist.com hint: PICList Posts must start with ONE topic: >>> [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads >>> >> >> -- >> http://www.piclist.com hint: PICList Posts must start with ONE topic: >> [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads >> >> >> >> > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

> My guess is that > the non-windowed versions have become popular enough to drive > prices lower than the windowed versions. That's precious! I'll have to save this post. Yet another hobbiest who thinks the world revolves around him. Windowed versions cost more because it takes extra steps to add the quartz window, which also forces the ceramic package. Most importantly, however, they are more expensive because the volumes are so low. The windowed parts were created so that code could be developed for OTP parts without requiring a new chip for every code tweak. The volumes are so low because the software engineer only needs a few during development, then OTP parts are used for volume production. ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, EraseMEolinspam_OUTTakeThisOuTembedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

On Mon, 18 Mar 2002, Olin Lathrop wrote: > hobbiest ^^^^^^^^ sed -e 's/hobbiest/hobbyist/g' > Windowed versions cost more because it takes extra steps to add the > quartz window, which also forces the ceramic package. Most > importantly, however, they are more expensive because the volumes are > so low. Agreed. > The windowed parts were created so that code could be developed for > OTP parts without requiring a new chip for every code tweak. Ummm... I think horse before cart. That's why the windowed version are still *sold*, but chronologically the OTP versions were created so that production quantities could be done without the added expense of the ceramic package and quartz window (or having a mask ROM version done). Windowed versions came first, OTP was a later idea. > The volumes are so low because the software engineer only needs a few > during development, then OTP parts are used for volume production. Yep. Dale -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads