Has anyone else had really bad luck with 28x1's? After using tons of 08M's and 18X's for years, and never losing a single one, I've somehow managed to brick 2 28X1's while working on the same project! I don't appear to be doing anything unusual, but this is starting to drive me crazy! (those things are expensive!).
bad luck with 28x1's?
- Thread starter Brietech
- Start date
I've had bad luck with 40X1 chips. I was putting them into pre-built circuit boards and for some reason I never was able to program them from the get-go.
I had 5 or so fail out of 10, which at the time was very perplexing. When I ordered more, I put them in without modifying anything on the circuit board and they worked.....
I have since bought an anti static workbench and wrist strap. I have also changed my habbits and I now turn off the power supply while plugging in and unplugging chips from their sockets. You might think I was crazy plugging in chips with the power on, but I was very careful with the orientation and the pins and I have done this for a long time, and have never had a failure before using the old 40X chips.
My only theory is that the in-built ESD protection is lower on the X parts which may have been a design constraint that was removed in order to increase the specs of other specifications of the chip.... just an unproven thought...
As for the 28X1 chips, I have probably used around 20 pcs of the SMD variants now, and have only had one failure due to baking too long in the home made reflow skillet (I think).
On this one dead one, a multimeter registered a short between 5V and Ground pins...
Are you noticing total failures? Or individual outputs or inputs going bad? Or chips drawing too much current?
If they have all died in the same way then let us know what the circumstances were and we might be able to provide some insight...
I had 5 or so fail out of 10, which at the time was very perplexing. When I ordered more, I put them in without modifying anything on the circuit board and they worked.....
I have since bought an anti static workbench and wrist strap. I have also changed my habbits and I now turn off the power supply while plugging in and unplugging chips from their sockets. You might think I was crazy plugging in chips with the power on, but I was very careful with the orientation and the pins and I have done this for a long time, and have never had a failure before using the old 40X chips.
My only theory is that the in-built ESD protection is lower on the X parts which may have been a design constraint that was removed in order to increase the specs of other specifications of the chip.... just an unproven thought...
As for the 28X1 chips, I have probably used around 20 pcs of the SMD variants now, and have only had one failure due to baking too long in the home made reflow skillet (I think).
On this one dead one, a multimeter registered a short between 5V and Ground pins...
Are you noticing total failures? Or individual outputs or inputs going bad? Or chips drawing too much current?
If they have all died in the same way then let us know what the circumstances were and we might be able to provide some insight...
leftyretro
New Member
I've used 28Xs, (one X and two X1s) mostly in a breadboard environment and have not had any problems to date after a year or so. Just got my first 08M around a month ago and the little guy is a lot of fun.
Anyway I do use well regulated commercial power supply moduules (+5V and + & - 12V) and have so far not reversed polarity or got the 5 and 12 mixed up
Lefty
Anyway I do use well regulated commercial power supply moduules (+5V and + & - 12V) and have so far not reversed polarity or got the 5 and 12 mixed up
Lefty
demonicpicaxeguy
Senior Member
i think it's more a batch by batch thing, i've had a few pics where certain outputs with a simple led attached to them via a resistor have just failed i had a 3 16f88's give up in a datalogger for no reason yet #4 in the same board is still going fine 2 years later,
1 thing to bear in mind is that in an devolopment environment these things can be handled quite a bit they are subjected to different levels of electrical noise they are turned on and off very frequently the program memmory is often flashed anything up to hundreds of times a day,
when it boils down to it, it's a tiny chip made to a price that was intended to be taken from the tube or tape and onto a board then programmed then sent on it's merry way to the consumer,
i know with my comercial developmnents i've gone through quite a few pics that have failed for seemingly no reason.
1 thing to bear in mind is that in an devolopment environment these things can be handled quite a bit they are subjected to different levels of electrical noise they are turned on and off very frequently the program memmory is often flashed anything up to hundreds of times a day,
when it boils down to it, it's a tiny chip made to a price that was intended to be taken from the tube or tape and onto a board then programmed then sent on it's merry way to the consumer,
i know with my comercial developmnents i've gone through quite a few pics that have failed for seemingly no reason.
Unless there is a genuine batch problem >99% of failures are user-caused. Inexperience, incompetence, unstable cups of coffee, 'little knowledge/learning is a dangerous thing', forgetfulness, 'I know better than the manufacturers' , whatever... even a slip of the finger.
I've used tons and sometimes if one pops I blame the chip obviously. Then I look at what I've done and realise I've boobed. The 'seemingly no reason' often turns into 'what a tw*t'.
I honestly doubt if Microchip have cut back on static protection such that it is, but none of these things are bullet-proof. I would agree that in most cases they go from box to customer but they are quite robust. And after all, the Fs are designed for re-programming (and flash write/read). But ATEOTD, most protection of the device is in your hands, the circuit designer.
Example: Read the FLIPPING Mchip Data Sheet and check out their recommended MCLR circuit - how many of you use it? Check out pro development boards - they've usually got it. So, up to you.
And plugging in while power on? Oooh, if you were unlucky and legs touched in the wrong order and your circuit wasn't good then you could have power going up the wrong hole. Yeah, I know you've been doing it man and boy , but NEWBIES beware - don't do this unless your parents give you their credit card and you don't mind waiting for delivery.
I was a little confused by DPG's paragraph 2. As there was no punctuation in it I wasn't sure whether he meant that because they get powered off/on a lot that this means they get flashed a lot. Or maybe it was a list of possibilities - punctuation often removes ambiguities Must be that old keyboard of his.
Bottom line; PICs - pretty tough, not indestructable and rely on a certain level of brain-power by the user. Developers should ALWAYS have a (quality) variable I/V bench PSU. Dumb not to unless you're a kid on a budget. Breadboards should really be OFF when twiddling. Data Sheets should always be read. And I should take notice of my own advice.
And Newbies - please start off with the cheapest dev/project board you can. You may think you saved some dosh, but if you blow it using your first hairy bread-board cos you mucked up then it's out with Mummy's credit card again innit. Oh and don't forget RTFM.
Don't blame the tools.
I've used tons and sometimes if one pops I blame the chip obviously. Then I look at what I've done and realise I've boobed. The 'seemingly no reason' often turns into 'what a tw*t'.
I honestly doubt if Microchip have cut back on static protection such that it is, but none of these things are bullet-proof. I would agree that in most cases they go from box to customer but they are quite robust. And after all, the Fs are designed for re-programming (and flash write/read). But ATEOTD, most protection of the device is in your hands, the circuit designer.
Example: Read the FLIPPING Mchip Data Sheet and check out their recommended MCLR circuit - how many of you use it? Check out pro development boards - they've usually got it. So, up to you.
And plugging in while power on? Oooh, if you were unlucky and legs touched in the wrong order and your circuit wasn't good then you could have power going up the wrong hole. Yeah, I know you've been doing it man and boy , but NEWBIES beware - don't do this unless your parents give you their credit card and you don't mind waiting for delivery.
I was a little confused by DPG's paragraph 2. As there was no punctuation in it I wasn't sure whether he meant that because they get powered off/on a lot that this means they get flashed a lot. Or maybe it was a list of possibilities - punctuation often removes ambiguities
Must be that old keyboard of his.Bottom line; PICs - pretty tough, not indestructable and rely on a certain level of brain-power by the user. Developers should ALWAYS have a (quality) variable I/V bench PSU. Dumb not to unless you're a kid on a budget. Breadboards should really be OFF when twiddling. Data Sheets should always be read. And I should take notice of my own advice.
And Newbies - please start off with the cheapest dev/project board you can. You may think you saved some dosh, but if you blow it using your first hairy bread-board cos you mucked up then it's out with Mummy's credit card again innit. Oh and don't forget RTFM.
Don't blame the tools.
BeanieBots
Moderator
Something which drives me nuts on this forum is comments along the lines of "I've run it like that for years with no problem" when another forum member suggests that a particular circuit might not be in the best interests of the chip. Series resistors with LEDs is a classic. Decoupling caps is another.
One which I personally "don't bother" with is pointed out by Dippy regarding the MCLR input. BUT I DO THAT AT MY OWN RISK.
Microchip don't publish these things for fun or because they have an alliance with other component manufactures.
Static damage is not to be scoffed at either. More often than not, a zap will cause instant damage, BUT NOT ALWAYS. In some circumstances a minor zap simply reduces the chip lifespan. In others, it alter the published safe maximum working tolerances. Either way, it alters the chip characteristics.
Running chips beyond out of spec can have similar effects. Many people think a chip can't be over current if does not get hot. Not true.
What do the big boys do.
I can answer that one. Any chip OR board not handled correctly is desposed of. They are not even tested. Simply chucked out if static precautions have not been observed. (you CAN'T test for non fatal static damage, the lifespan is simply compramised by an unkown amount).
Inserting with power on.
I'll say it the way it is. That is plain STUPID.
I don't recommend changing spark plugs on a car with the engine running either.
One which I personally "don't bother" with is pointed out by Dippy regarding the MCLR input. BUT I DO THAT AT MY OWN RISK.
Microchip don't publish these things for fun or because they have an alliance with other component manufactures.
Static damage is not to be scoffed at either. More often than not, a zap will cause instant damage, BUT NOT ALWAYS. In some circumstances a minor zap simply reduces the chip lifespan. In others, it alter the published safe maximum working tolerances. Either way, it alters the chip characteristics.
Running chips beyond out of spec can have similar effects. Many people think a chip can't be over current if does not get hot. Not true.
What do the big boys do.
I can answer that one. Any chip OR board not handled correctly is desposed of. They are not even tested. Simply chucked out if static precautions have not been observed. (you CAN'T test for non fatal static damage, the lifespan is simply compramised by an unkown amount).
Inserting with power on.
I'll say it the way it is. That is plain STUPID.
I don't recommend changing spark plugs on a car with the engine running either.
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In defence of the newbies and those who don't have much electronics experience, unless someone tells them they know no better and can only copy what others do, often without knowing or understanding why.
Everything said here is indeed valid, but why would anyone question how reset or the download RS232 interface is implemented when they are simply following what the manuals tell them to do ?
"How vulnerable to damage are the microcontrollers? : The microcontrollers have a high level of static protection built into each pin and so handling them without any personal static protection in an educational environment is perfectly acceptable."
We could have a long discussion over that, but the question is how would a newbie or home user interpret such a thing ?
Bottom line is that I don't think it's entirely fair to blame someone who 'does something stupid' if they don't know any better.
Everything said here is indeed valid, but why would anyone question how reset or the download RS232 interface is implemented when they are simply following what the manuals tell them to do ?
"How vulnerable to damage are the microcontrollers? : The microcontrollers have a high level of static protection built into each pin and so handling them without any personal static protection in an educational environment is perfectly acceptable."
We could have a long discussion over that, but the question is how would a newbie or home user interpret such a thing ?
Bottom line is that I don't think it's entirely fair to blame someone who 'does something stupid' if they don't know any better.
A certain truth, maybe I'm harsh.
But "..they are simply following what the manuals tell them to do ?"
- there is considerable evidence that a few people don't do this. LEDs.. resistors... etc.
If the manuals were followed, E&OE, then the circuit will work.
"Bottom line is that I don't think it's entirely fair to blame someone who 'does something stupid' if they don't know any better. "
- don't you? In some circumstances I do.
Anyway, this could go on into Nesbitt dimensions. Bored now...
But one last thing: where did you get that quote hippy? I'm intrigued.
But "..they are simply following what the manuals tell them to do ?"
- there is considerable evidence that a few people don't do this. LEDs.. resistors... etc.
If the manuals were followed, E&OE, then the circuit will work.
"Bottom line is that I don't think it's entirely fair to blame someone who 'does something stupid' if they don't know any better. "
- don't you? In some circumstances I do.
Anyway, this could go on into Nesbitt dimensions. Bored now...
But one last thing: where did you get that quote hippy? I'm intrigued.
BeanieBots
Moderator
Hippy, I agree. My gripe is aimed at people who give them the advice.
I have seen countless comments here stating that they have run PICAXEs without LED resistors without problems after an earlier post has stated that they need to be added.
As for inserting a chip into a powered socket. I could explain all the different ways in which it could (or even could not) destroy the chip but I stick with my original comment. It's just plain stupid. Most other scenarios are based on lack of knowledge and warrant a fair explanation of why or why not.
We've all heared the "classic" accounts of helpdesk calls to Microsoft such as the person asking why their PC does not work only to discover that they have a power cut, and the person trying to send a fax by holding the paper up to the screen. Such calls really do warrant the reply of "please return your PC, you don't deserve one".
This is a real call that I once took about a remote control.
(industrial, NOT commercial sector)
The caller asked "Does it matter which way around the batteries go?"
Page one of the manual states, "be sure to insert the batteries the correct way around".
The plastic on the remote is embossed with a clear picture of the battery orientation. The inside cover has a large label emphasing correct polarity (also with diagram) and the design is such that it almost impossible to insert them incorrectly.
I replied with, "please hold the line while I find out".
I kept them waiting for nearly 20 minutes and was genuinely surprised to find them still on the line. I still think it was a crank call but who knows.
I have seen countless comments here stating that they have run PICAXEs without LED resistors without problems after an earlier post has stated that they need to be added.
As for inserting a chip into a powered socket. I could explain all the different ways in which it could (or even could not) destroy the chip but I stick with my original comment. It's just plain stupid. Most other scenarios are based on lack of knowledge and warrant a fair explanation of why or why not.
We've all heared the "classic" accounts of helpdesk calls to Microsoft such as the person asking why their PC does not work only to discover that they have a power cut, and the person trying to send a fax by holding the paper up to the screen. Such calls really do warrant the reply of "please return your PC, you don't deserve one".
This is a real call that I once took about a remote control.
(industrial, NOT commercial sector)
The caller asked "Does it matter which way around the batteries go?"
Page one of the manual states, "be sure to insert the batteries the correct way around".
The plastic on the remote is embossed with a clear picture of the battery orientation. The inside cover has a large label emphasing correct polarity (also with diagram) and the design is such that it almost impossible to insert them incorrectly.
I replied with, "please hold the line while I find out".
I kept them waiting for nearly 20 minutes and was genuinely surprised to find them still on the line. I still think it was a crank call but who knows.
I agree there are indeed some apparently dumb people around ( or more politically correct these days, experience challenged ) who don't see what's obvious to the majority. It can be hard to maintain any degree of sympathy for such levels of ignorance and particularly when documentation clearly clarifies the situation. There's a minority who have legitimate excuses for their predicaments, unfortunately most do not.
@ Dippy : That handling 'warning' is from PICAXE Manual 1, page 87.
@ Dippy : That handling 'warning' is from PICAXE Manual 1, page 87.
Mycroft2152
Senior Member
Dippy,
You are not reading the manuals?
You are not reading the manuals?
I realize that I probably just zapped it or something, I've just been having an unusually bad string of luck with this project and felt like ranting a little. For what it's worth, I don't insert chips when the power is on, and I have caps/resistors in appropriate places (although I must admit that my tiny apartment does not allow for a nice ESD-safe workstation *sigh* - I just use my kitchen table).
A kitchen table probably isn't a bad place to work. You won't be shuffling your feet on a carpet while you're handling sensitive electronic components.
Before you pick up a chip, get your body at the same potential as the chip. You do this by touching the surface where the chip rests with one hand. Holding that hand on the surface, touch your other hand briefly to the surface, then pick up the chip.
Be very careful when you're carrying that chip.
Before you set it down, follow the same procedure. Touch the surface where the chip is going with your free hand, and hold it there. Touch that surface with the little finger of the hand holding the chip, then set it down.
You probably won't cause too much damage if you're always careful not to have any potential difference between your body and the chips.
You live and you learn.
Good luck!
Tom
"Dippy,
You are not reading the manuals?"
- guilty. Though I think that page was missing in my copy
Seriously though, my actual (lame) excuse is that I tend to go to manuf's Data Sheet for hardware.
And, no of course I haven't read the Data Sheet end-to-end. I have actually got a life believe it or not. 20th Century Telegraph posts.
You are not reading the manuals?"
- guilty. Though I think that page was missing in my copy
Seriously though, my actual (lame) excuse is that I tend to go to manuf's Data Sheet for hardware.
And, no of course I haven't read the Data Sheet end-to-end. I have actually got a life believe it or not. 20th Century Telegraph posts.