How to identify a fried chip?
- Thread starter sreedev
- Start date
A test with a Multimeter may not be conclusive, and you may need a known good chip to compare against.
One sure sign is that current consumption of the chip is excessive, should normally only be a few ma.
That said, by far the easiest way is to connect it in circuit, with a current limited supply if possible, and see if it programs, is there a reason why you cant do this ?
One sure sign is that current consumption of the chip is excessive, should normally only be a few ma.
That said, by far the easiest way is to connect it in circuit, with a current limited supply if possible, and see if it programs, is there a reason why you cant do this ?
westaust55
Moderator
As srnet indicates excessive current which can also be detected as a high temperature (hot when finger placed on energised chip).
Other forum members before you have also managed to apply reverse voltage and the PICAXE chips have in many cases survived (they are fairly tolerant of some abuse).
However even if all seems well it is possible that a single transistor or logic gate has failed which may not be detected quickly without perfoiming many tests of all of he chips many features.
In summary, try the suspect chip and if it does seem to function normally, then mark it as "suspect" (eg with a dab of red paint) and use iot but be aware that if later problems arise it could be damage from the past and try a new chip before seeking help on the forum that may sent others on a wild goose chase trying to diagnose a programming or circuit related problem.
Other forum members before you have also managed to apply reverse voltage and the PICAXE chips have in many cases survived (they are fairly tolerant of some abuse).
However even if all seems well it is possible that a single transistor or logic gate has failed which may not be detected quickly without perfoiming many tests of all of he chips many features.
In summary, try the suspect chip and if it does seem to function normally, then mark it as "suspect" (eg with a dab of red paint) and use iot but be aware that if later problems arise it could be damage from the past and try a new chip before seeking help on the forum that may sent others on a wild goose chase trying to diagnose a programming or circuit related problem.
Follow srnet's suggestion; plug it in preferably with a current-limited supply or batteries and check current with a brief power-up.
If only a few mA try programming something simple and quick. And use Thumb-ometer to test heating. And use a nose to detect for tex's smoke.
As Westy says, there are occasions when a section of the PIC hardware (peripheral) may have failed.
I had a cak-handed moment with a dsPIC once and a single ADC channel had died. I wasted loads of time wondering why my circuit was giving daft results.
Some people mark an apparently uC as 'potentially iffy' and save it for specific work.
Some people run a diagnostic programme to see if any of the peripherals are playing up.
I usually bin it as I am a lazy git and don't want to run the risk that abuse may have partially upset something.
You may be alright and ideally you will two PICAXEs so you can test side-by-side.
(Buying singly during the learning curve is a mistake).
Sooner or later you will have to try it out. Make it sooner and put yourself out of your misery
Treble check all your connections and supply, Keep it simple and try it.
If only a few mA try programming something simple and quick. And use Thumb-ometer to test heating. And use a nose to detect for tex's smoke.
As Westy says, there are occasions when a section of the PIC hardware (peripheral) may have failed.
I had a cak-handed moment with a dsPIC once and a single ADC channel had died. I wasted loads of time wondering why my circuit was giving daft results.
Some people mark an apparently uC as 'potentially iffy' and save it for specific work.
Some people run a diagnostic programme to see if any of the peripherals are playing up.
I usually bin it as I am a lazy git and don't want to run the risk that abuse may have partially upset something.
You may be alright and ideally you will two PICAXEs so you can test side-by-side.
(Buying singly during the learning curve is a mistake).
Sooner or later you will have to try it out. Make it sooner and put yourself out of your misery
Treble check all your connections and supply, Keep it simple and try it.
inglewoodpete
Senior Member
The 28X1 is the only PICAXE that I have inserted the wrong way. It survived. It happened about two years ago and I don't remember if it got hot or not. However, the chip was undamaged for the purpose that I used it for.
hippy
Ex-Staff (retired)
You can get lucky as reversed chip insertion isn't always the same as reversing power. On some it is though.
If power ends up going into I/O pins the internal ESD diodes can act as a bridge rectifier and the internal silicon will still be powered with correct polarity. It then likely depends on what else it connects to as to whether anything bad happens.
Actual power supply reversal and over voltage are more likely to cause damage than not but current limited supplies and shorter periods of wrong connection can save the day.
After double-checking the hardware, power supply, Hard Resets and the like, often the best way to test if a chip is fried is doing comparative testing. If the hardware and everything else is right, if one chip works and another doesn't, then the one that doesn't work is probably fried.
Test 1: Check the current with only Power Pins & Download resistors connected to Picaxe.
A. More than about 2 Ma ... Chip is likely bad but may seem good. See note below
B. Less than 2ma ... Go To Test 2
Test 2: Attempt to Program the Chip with blank program or "Clear hardware Memory".
A. Failure ... Go To Test 3
B. Success .... Chip is likely good
Test 3. Attempt to Program using a hard reset.
A. Fail > Try another Picaxe chip in the same socket. IF it programs OK then first chip is likely bad
B. Success > Chip is likely good
Note: If the chip programs OK but the idle current is greater than about 2ma with a blank program and nothing connected, then it is highly likely that an internal peripheral or I/O has failed. The chip may seem to work fine, however problems could show up with timing sensitive commands, or commands that use the hardware USART or other internal peripherals. Set this chip aside as "iffy" or bin it completely .
I have had one 8m2 and one 18M2 fail, likely due to applied over voltage. In each case both programed ok and seemed to work ok. But afterward, the idle current was approximately 30ma for each chip. The chips did not feel warm to the touch. They were scrapped without further testing.
A. More than about 2 Ma ... Chip is likely bad but may seem good. See note below
B. Less than 2ma ... Go To Test 2
Test 2: Attempt to Program the Chip with blank program or "Clear hardware Memory".
A. Failure ... Go To Test 3
B. Success .... Chip is likely good
Test 3. Attempt to Program using a hard reset.
A. Fail > Try another Picaxe chip in the same socket. IF it programs OK then first chip is likely bad
B. Success > Chip is likely good
Note: If the chip programs OK but the idle current is greater than about 2ma with a blank program and nothing connected, then it is highly likely that an internal peripheral or I/O has failed. The chip may seem to work fine, however problems could show up with timing sensitive commands, or commands that use the hardware USART or other internal peripherals. Set this chip aside as "iffy" or bin it completely .
I have had one 8m2 and one 18M2 fail, likely due to applied over voltage. In each case both programed ok and seemed to work ok. But afterward, the idle current was approximately 30ma for each chip. The chips did not feel warm to the touch. They were scrapped without further testing.
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Thanks to all of you for your concern.....Moreover, I cannot program the chip with a usb programmer for picaxe and also the AXE027. This had been the condition from the time I got it. It came with the starter 28/1 pack. The terminal window gives no messages when the baud rate is set to 9600. Help.
What USB programmer are you referring to ?
So, it has actually never worked ... and you are sure you plugged the chip in backwards and applied power ?
What is your power source? If batteries, what kind ?
Where did the starter kit come from ?
Where did the Picaxe 28X1 Chip come from?
Did you plug in the chip and measure the current ? What was it ?
Did you try a "hard reset" ?? This is an important step to try.
To perform a hard-reset using the reset switch (28, 40 pin PICAXE):
1) Press and hold down the reset switch.
2) Click the PICAXE>Program menu to start a download.
3) Wait until the progress-bar appears on screen.
4) Wait 1 second then release the reset switch.
To perform a hard reset using the power supply (all sizes):
1) Disconnect the power supply.
2) Wait until all power supply decoupling capacitors have discharged (can take
up to 30 seconds or more depending on circuit design).
3) Click the PICAXE>Program menu to start a download.
4) Wait until the progress-bar appears on screen.
5) Reconnect the power supply
1) Press and hold down the reset switch.
2) Click the PICAXE>Program menu to start a download.
3) Wait until the progress-bar appears on screen.
4) Wait 1 second then release the reset switch.
To perform a hard reset using the power supply (all sizes):
1) Disconnect the power supply.
2) Wait until all power supply decoupling capacitors have discharged (can take
up to 30 seconds or more depending on circuit design).
3) Click the PICAXE>Program menu to start a download.
4) Wait until the progress-bar appears on screen.
5) Reconnect the power supply