Home |
Search |
Today's Posts |
#1
Posted to alt.electronics
|
|||
|
|||
Corrupt Flash Memory Discussion
Before I get into the nitty-gritty of the problem, I would like to know the
consensus on whether Flash Memory can be corrupted by anything other than cosmic rays, nuclear detonation, and the occasional ray gun. All kidding aside, does anyone have any information on EMI, and/or RFI causing bits to flip? Best regards, elarson |
#2
Posted to alt.electronics
|
|||
|
|||
Corrupt Flash Memory Discussion
"Eric L." wrote in message news:94pdg.14540$B42.9190@dukeread05... Before I get into the nitty-gritty of the problem, I would like to know the consensus on whether Flash Memory can be corrupted by anything other than cosmic rays, nuclear detonation, and the occasional ray gun. All kidding aside, does anyone have any information on EMI, and/or RFI causing bits to flip? Best regards, elarson I bet if you put a Flash Memory chip in liquid helium some of the bits would drop out, and maybe -20 F.. I don't know, but it could happen if it gets cold or hot enough. I think you can exclude EMI wavelengths longer than 4 times the longest edge of the device from considiration as having no effect whatsoever. That means radio waves below microwaves would have to be extremely powerful to effect the device. Put the chip in a microwave, turn it on, then test.... and if my guess is right, there will be problems. I think it would probably turn out that you have to hit the chip-level electronics with ultraviolet light to have any hope of flipping bits.. and gamma radiation would be more effective. If the memory is inside a metal case, it would be better off for reliability. If I were on a jury however, I would conclude that bit-flipping is too far-fetched a defense. the wavelength of the offending EMI has to be shorter than four times the length of the structure it interacts with, to interact with it substantially.. furthermore it has to result in enough 'kick', the rush of phonons from the strike spot to cause enough electron excitation to bump the voltage enough to cause the bit to change and still the circuit has to be susceptible to register this change.. so its an unlikely proposition even if you try... but if you try a few billion times as in a radioactive minute you might have some luck. RFI is EMI limited to the RF bands. If you record 1,000,000 flash memories then drop them all, one at a time, 3 feet onto the pavement, 50 of them will have permanent errors from breakage. If you record 1,000,000 flash memories then read them back, one or two will have non-repeatable errors... thats just the way it goes (without recourse to voodoo or microsoft). If that's true it's a one in a million chance for just bad luck with 'bit retention'. Another thing is ageing. Since the 'decay' of chemistry within the chip is a function of time..it would stand to reason that with every passing second flash memory is more vulnerable to failure. After 100 years there is a slim chance that much data could still be intact. 0 will still be zero, but adjusting for inflation, 1 will be around 27 (which screws up binary), and gasoline will be $421 per milliliter (synthetic) - converted from yen since the dollar won't exist, having since surpassed itself by it's value as heating fuel and toilet paper. hope that helps elvis |
#3
Posted to alt.electronics
|
|||
|
|||
Corrupt Flash Memory Discussion
"Elvis Presley" wrote in message
... "Eric L." wrote in message news:94pdg.14540$B42.9190@dukeread05... Before I get into the nitty-gritty of the problem, I would like to know the consensus on whether Flash Memory can be corrupted by anything other than cosmic rays, nuclear detonation, and the occasional ray gun. All kidding aside, does anyone have any information on EMI, and/or RFI causing bits to flip? Best regards, elarson I bet if you put a Flash Memory chip in liquid helium some of the bits would drop out, and maybe -20 F.. I don't know, but it could happen if it gets cold or hot enough. I think you can exclude EMI wavelengths longer than 4 times the longest edge of the device from considiration as having no effect whatsoever. That means radio waves below microwaves would have to be extremely powerful to effect the device. Put the chip in a microwave, turn it on, then test.... and if my guess is right, there will be problems. I think it would probably turn out that you have to hit the chip-level electronics with ultraviolet light to have any hope of flipping bits.. and gamma radiation would be more effective. If the memory is inside a metal case, it would be better off for reliability. If I were on a jury however, I would conclude that bit-flipping is too far-fetched a defense. the wavelength of the offending EMI has to be shorter than four times the length of the structure it interacts with, to interact with it substantially.. furthermore it has to result in enough 'kick', the rush of phonons from the strike spot to cause enough electron excitation to bump the voltage enough to cause the bit to change and still the circuit has to be susceptible to register this change.. so its an unlikely proposition even if you try... but if you try a few billion times as in a radioactive minute you might have some luck. RFI is EMI limited to the RF bands. If you record 1,000,000 flash memories then drop them all, one at a time, 3 feet onto the pavement, 50 of them will have permanent errors from breakage. If you record 1,000,000 flash memories then read them back, one or two will have non-repeatable errors... thats just the way it goes (without recourse to voodoo or microsoft). If that's true it's a one in a million chance for just bad luck with 'bit retention'. Another thing is ageing. Since the 'decay' of chemistry within the chip is a function of time..it would stand to reason that with every passing second flash memory is more vulnerable to failure. After 100 years there is a slim chance that much data could still be intact. 0 will still be zero, but adjusting for inflation, 1 will be around 27 (which screws up binary), and gasoline will be $421 per milliliter (synthetic) - converted from yen since the dollar won't exist, having since surpassed itself by it's value as heating fuel and toilet paper. hope that helps elvis Thank you for your comments. I would like to direct your attention to the center ring: http://www.eng-tips.com/viewthread.cfm?qid=155287 I have been having a discussion with a number of engineers over a special little topic. I think you will find this most interesting. I would be interested in what you have to say. elarson |
#4
Posted to alt.electronics
|
|||
|
|||
Corrupt Flash Memory Discussion
Thanks for your input. What is the recommended test setup for testing for
EMI/RFI? elarson "Dan H" wrote in message ps.com... Eric L. wrote: Before I get into the nitty-gritty of the problem, I would like to know the consensus on whether Flash Memory can be corrupted by anything other than cosmic rays, nuclear detonation, and the occasional ray gun. All kidding aside, does anyone have any information on EMI, and/or RFI causing bits to flip? Best regards, elarson I have seen effects when a system was being tested for EMI/RFI immunity. At certain frequencies that microproc oscillator was affected, confused the micro and cause false data to be written to memory chip. Dan |
#5
Posted to alt.electronics
|
|||
|
|||
Corrupt Flash Memory Discussion
Eric L. wrote: Thanks for your input. What is the recommended test setup for testing for EMI/RFI? elarson It depends on the application and what the legal requirements are - for example If the product is to be sold in the European Union there detailed specifications as to how the tests must be done. These require the equipment be tested in a special built facility with special test equipment to do the tests. If you just want a confidence check, you can take a hand help VHF transmitter, hold the antenna about 6 inches from your product while it is running and key it on and off while tuned to different frequencies and observe the product operation for unusual events. To do a crude test for immunity to electrical spikes wire the contact of a relay in series with the power to the relay so that it acts as a buzzer. Connect a wire from one end of the relay coil connected to the relay contact thru a capacitor and then connect it one at a time to the power leads and the input and output leads of the product. Monitoring for abnormal operation of the product. Without careful design few products will pass even the above tests the first time they are applied. And of course once you have a product which is immune to outside influence then you need to run test to see if it is emitting unwanted RF to the air or on the power lines. More special equipment and facilities required. Hope this helps Dan |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
microcontroller flash memory question | Electronics | |||
OT - 386 code | Metalworking | |||
FS: Microchip ICE 2000, Modules, Adapters, PICStart Programmer, ICD, IC's | Electronics | |||
FS: Semiconductor Data Books | Electronics Repair | |||
Remote Sensor for Underwater Flash Strobe | Electronics Repair |