I have an ATTINY841 that is utilizing a Dataflash SPI flash chip (AT45DB011D). The SPI pins are connected to the same pins used for programming the ATTINY841. When I program the ATTINY841, I find that the Dataflash chip is being erased, and I have to reprogram it also. This happens even though the Write Protect pin on the Dataflash is asserted (connected to Ground). To prevent this I currently need to remove the Dataflash from the circuit when programming the ATTINY841 and replacing it when finished, however I won't be able to do that when the circuit is transferred to PCB. Has anyone experienced this or know how to deal with it? Do I have a bad chip?

  • Show some schematic. Are you also making sure that the chip select pin on the dataflash is staying high while you program? – Delta_G Oct 9 '17 at 16:06
  • The obvious solution is to provide jumpers in your circuit to isolate the pins you need for programming. Maybe incorporated as part of the programming header... – Majenko Oct 9 '17 at 17:16

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