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JoeS,
Your posts noted and changes made. I am pondering why my chip is not working. If the chip is damaged, won't the programmer verify step resulted in an error? What's next after LED test failed? I have another pci16gf627A chip. I am afraid that I might damage it too.
Regards,
JohnPaul
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ski,
I like your 'heartbeat' practice. I would adapt it as my practice too.
Regards,
JohnPaul
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Put a voltmeter on the OSCx pins. You should get around 2.5v with an external oscillator, or if you've got OSC2 setup as an Fosc/4 output.Originally Posted by JohnPaul
I wouldn't think you smoked a chip...as has been noted before, PICs are fairly tough chips, not unbreakable, but tough.
And if for some reason, your PIC is running on the 48khz internal clock, your program will run about 83 times slower than it should...in other words it'll take 166 seconds for your LEDs to blink.
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Ski,
Hmm. I am not yet familiar with the OSC parameter settings.
I did the LED test without any of the additional DEFINE and @ statements beside the ones that I posted.
I waited 5-10 minutes for the LED to light up on pin 6. But the chip and bottom of the bread board were getting hot so I pulled the power off.
I just checked again. I think that I might have really burned my chip this time.
I placed the voltmeter on 0 and +5V, and I would read +5v. But the moment I connect my +5v cable to VDD (pin 14). The voltmeter reading would drop to 1.67v?
Regards,
JohnPaul
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Ok, get rid of everything but the power supply (connect a light bulb across it, verify 5v under a small load, use 3 alkalines or 4 NiCads instead of a power supply), the PIC16F627A, an LED with a 300-ish ohm resistor in series, 10K pullup to +5v on MCLR, and some sort of crystal/oscillator setup on OSC1... and put a small cap across Vdd and Vss on the PIC (very important step here!)
Double check your pin 1 on the PIC and plug it in.
Break it down...break it WAY down to bare bones.
Rewrite the program, simplify it as far as you can, one LED or a group of LEDs, doesn't matter, same thing, blink the LED...
Let us know what you've got after you get it broke down...
I don't think you've fried anything (although it's entirely possible), I think you're just forgetting something basic, and when that gets figured out, everything else will fall into place faster than you can spend money on it
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Dear Ski,
Hahaha... Blinking the LED is the first project in the book and I thought it's so simple so I read all the projects but did not tried any of the LEDs .... skipped all the project all the way to the LCDs. Now, I am back... to LED1.BAS
I will get a new chip and tried the LED Blinking tomorrow and start anew.
It's late now.
Thank you very much! I greatly appreciate your help.
Regards,
JohnPaul
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Excellent plan! There's a reason why all these books and websites have Blink.Bas as their first project.
Once you get that working, you change the blink rate by changing the program, you add a couple of buttons which when pressed will change the blink rate depending on the button press......and it just goes up from there....then you get to spend money buying up neat stuff to play with....which is when the wife starts to disown you and you start to go broke and ...........
Never mind...
Enjoy
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Hi JohnPaul,
You would think so wouldn't you, but the short answer is no, I have killed a few PICs and had programs verify fine, I think I killed the output transistors while the core of the pic remained undamaged. You would do well if using an old breadboard to either replace it or use an ohmmeter to verify all connections, I have been led to the land of little hair as a result of these.
JS
If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
.
Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants - but debt is the money of slaves
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There simply is no "Happy Spam" If you do it you will disappear from this forum.
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Joes & Ski,
Thank you for the help.
JoeS,
Using an Ohmeter, which pins do I tap, what to expect and why? I would also do the Ohmeter test on a new chip alongside with this chip in question.
Regards,
JohnPaul
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MCLR / Vdd - 5v (if running a 5v power supply, otherwise, take all these reading and divide them down accordingly)
Vss - 0v
OSC1 / OSC2 - with an external oscillator/crystal, somewhere around 2.5v give or take, because the meter is really reading DC, it's catching the average of the DC, which since it's going high/low/high/etc, is around 2.5v.
Pins set to an input will most likely read about 2.5v, or a suitable fraction of the main power supply voltage.
Pins set to output and logic low will be between 0v and about .6v
Pins set to output and logic high will be around 7/10 of the main power voltage.
All interconnects on your breadboard should be practically a dead short, like less than about 10 ohms or so. Don't forget to check your multimeter leads themselves for resistance.
Hopefully this is what you were asking about. Sounds a tad bit basic to me, but that's just me...
By checking the new chip against the old chip alongside it in identical circuits, you are doing what I call a 'signature check', good troubleshooting technique, but it really only works if you've got a couple of known good working setups to verify another bad setup.
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Hi JP,
Pretty much as skimask said, just check from the leads of the components to where they are supposed to be connected ( the other component ). These breadboards get really spooky over time. Darrel told me he only uses them once. That's too rich for my blood but my time is perhaps less valuable. Certainly I do not do this for a living. I dissasembled my old breadboards and was very surprised at what I found in the way of wear and corrosion. This is especially important on the VSS & VDD connections so power flows through the device in the way it's designers intended, otherwise very strange current paths can exist and FRY something.
JS
Last edited by Archangel; - 22nd May 2007 at 22:55.
If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
.
Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants - but debt is the money of slaves
.
There simply is no "Happy Spam" If you do it you will disappear from this forum.
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Howdy, partners.
Hey, folks. No progress today... Hehehe... I actually mean I slacked off. I could not find my other 627A. Use of magnifier did not helped. I would try the 84A but have to use OSC chip or I have to use my 40 pins. I could not wait for the weekend to come.
What is the most advanced PIC chip one could wish for? I like my 627A since it has internal OSC.
I am reserving my 40 pins for more complexed project in the future.
Cheers!
John Paul
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JohnS,
I bought this regulated variable PS. They go by 1.5, 3, 4.5, 6, 9v, 12v.
No +5v! I like it because it's so portable than those high Amp PS. So I was playing with the PIC with 4.5v and ocassionally switching to 6v. Could I have caused the untimely dead of my PIC?
Later, I retrieve one of my breadboard with a T7805. Just to make sure the LCD and Chip now has the recommended (or was it REQUIRED) voltage?
Hahaha...
Regards,
JohnPaul
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The PIC (and everything else mentioned so far) will run just fine off 4.5v, and the occassional switchover to 6v probably won't hurt it much either. Datasheets say 7V is 'absolute maximum' rating, not recommended for any length of time. I've accidentally ran a couple of my PIC's at 9v before, they still run, not saying they're not damaged and won't fail before the others, but they do still work.
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Ski,
I might have pulled the PIC while the power is on. Also, I might have pulled a wire while powered on. I am using a breadboard wire that I like because they are more flexible and easy to insert but I wondered could high current be generated with "loose" connection?
Hehehe... I have done my testimony. Guilty for the dead of my pic? Hahahaha..... I would play with the pic16f84a tonight and catch up with you and Joe.
Regards,
JohnPaul
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