Flash Memory Endurance Testing

[Gene] has a project that writes a lot of settings to a PIC microcontroller’s Flash memory. Flash has limited read/erase cycles, and although the obvious problem can be mitigated with error correction codes, it’s a good idea to figure out how Flash fails before picking a certain ECC. This now became a problem of banging on PICs until they puked, and mapping out the failure pattern of the Flash memory in these chips.

The chip on the chopping block for this experiment was a PIC32MX150, with 128K of NOR Flash and 3K of extra Flash for a bootloader. There’s hardware support for erasing all the Flash, erasing one page, programming one row, and programming one word. Because [Gene] expected one bit to work after it had failed and vice versa, the testing protocol used RAM buffers to compare the last state and new state for each bit tested in the Flash. 2K of RAM was tested at a time, with a total of 16K of Flash testable. The code basically cycles through a loop that erases all the pages (should set all bits to ‘1’), read the pages to check if all bits were ‘1’, writes ‘0’ to all pages, and reads pages to check if all bits were ‘0’. The output of the test was a 4.6 GB text file that looked something like this:
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Cell Phone Endurance Tests

Gone are the days when a phone would last you a lifetime and enter the days of glass covered mobile phones built to be sexy and sophisticated. With these new phones come new testing methods. Companies like Nokia are still dedicated to making the best phones possible and making them durable through vigorous testing. The example shown in the article, is simulating a phone dropping from a shirt pocket onto the floor. Nokia claims to use 200 endurance tests encompassing temperature, extreme usage (use this button pusher for you own test), physical drops, and exposure to humidity on each new model in their product line. Makes one wonder what other companies are using for their endurance tests. There’s video of the Nokia N8 Drop Test is after the break, and don’t forget to leave a comment if you know about other interesting test methods.

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