nRF52 Flash memory vs EEPROM

Question

If we want to save some data, (as I think) we have two options. 
 Flash memory in nRF52832 or external EEPROM. 
 could you tell me pros and cons of two? 
 
 my guess 
 
 external EEPROM = additional cost 
 external EEPROM = additional port needed 
 Flash memory - might cause conflict BLE works and saving works 
 Flash memory has bigger page, so may takes more time to operate 
 Flash memory might be unstable of Flash memory API

endnode · Accepted Answer

You got it right I believe, not much to add. Internal flash in nRF5x chips is pretty slow (erasing), it is blocking MCU (so if Soft Device runs some heavy BLE operation - such as connection with low connection interval - it can be postponing erase which can cause troubles, you also need to go through SoftDevice API for flash access if you want to do some operation while SD is enabled) and it has pretty large pages (1kB on nRF51 and 4kB on nRF52) which makes some standard use cases problematic (e.g. some filesystem with low overhead/file size). So the question you should ask yourself is: "What NVM storage use cases you need to support on your product?" and this will give you very good hint if you need to invest into external memory chip (whatever flash or EEPROM) or not. It costs you BOM, PCB real estate, one bus (typically SPI) on nRF5x chip + FW integration (driver).

nRF52 Flash memory vs EEPROM

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