On 12/17/2016 03:26 PM, Luka C wrote: > I'm writing this to warn others or ask if anyone had similar experiences. I > purchased a lot of Atmel ATMEGA328P microcontrollers from a seller on > Aliexpress.
Microprocessors are one component that you absolutely MUST buy from an authorized distributor or directly from the manufacturer. ESPECIALLY Atmel. Instead of trashing chips that fail testing, Atmel apparently allows them to leave the factory to be sold by unscrupulous resellers. Atmel is what is known as a foundryless manufacturer. That is they have hunks of silicon logic manufactured by someone else. They then load microcode into the chip to turn it into an ATMEGA or whatever. The nature of this process is that the chip can fail to execute certain instructions, fail to drive pins while the rest of the chip works. There can also be parts of the chip that won't run at the specified speed. I just ran into that with the AT90PWM316. My (now ex) partner got a "great deal" on some parts through OctoPart. At the programming frequency loaded into Studio, the chip reported the signature of an unrelated chip. As a last ditch hunch, I slowed the programming frequency down to about 50kHz. IT then reported the correct signature and accepted my program, though it took several minutes instead of seconds. Since they abruptly and without warning EOL'd that chip shortly after the MicroChip takeover and the going rate for remaining stock is about $15 (was $4), I'm going to have to try to use them. I recently ran into a similar problem, this time with parts from Mouser. Suddenly with this lot of chips, the "heat" button (induction heater) works only sometimes and about half the time the unit comes up at full power instead of the set power level. I haven't yet pin-pointed what is going wrong so once we use up the OctoPart parts, we'll be down for the count until I can redesign the board to use a different processor. I'm fed up with Atmel. After someone mentioned it here earlier, I took at look at the TI MXP432 ARM processor. About the same price but vastly more powerful. The TI LaunchPad (think Arduino) is only 12 dollars and is set up like the Arduino to accept daughterboards. Ti's support has been great. This is the chip I'm converting to. Back to the issue at hand, never ever ever buy complex parts whose origin cannot be traced back to the manufacturer and even then expect problems. John -- John DeArmond Tellico Plains, Occupied TN http://www.tnduction.com <-- THE source for induction heaters http://www.neon-john.com <-- email from here http://www.johndearmond.com <-- Best damned Blog on the net PGP key: wwwkeys.pgp.net: BCB68D77 -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/85da9196-6404-2d56-189f-1d20a736fe43%40neon-john.com. For more options, visit https://groups.google.com/d/optout.
