Why do we need to add an external EEPROM when using some MCUs?

小太阳yy

Why do we need to add an external EEPROM when using some MCUs? [Copy link]

 

Why do we need to add an external EEPROM when using some MCUs? Why do some projects not add it, but others do?

wangerxian

See if the MCU's own memory is sufficient to store the data. If not, an external EEPROM is needed to store the data.

小太阳yy

wangerxian posted on 2022-5-11 15:55 It depends on whether the MCU's own memory is enough to store data. If it is not enough, an external EEPROM is needed to store data.

If it’s not enough, why not just choose an MCU with larger memory?

littleshrimp

EELROM can store some frequently read and written content, such as changing channels on a TV. The number of times the FLASH of the microcontroller is erased and written is relatively small.

wangerxian

Xiao Taiyangyy posted on 2022-5-11 16:06 If it is not enough, why not choose an MCU with larger memory?

If the maximum memory of the MCU cannot meet the needs, it must be expanded externally. Moreover, as the product functions increase, the code will also occupy the MCU's Flash. Taking all factors into consideration, some products will use external EEPROM.

Especially for those with pictures and audio, you may consider external Flash or SD card.

The existence of EEPROM certainly has its uses, and whether to expand externally needs to be considered based on the product.

maychang

"Why do we need to add an external EEPROM when using some MCUs?"

If it is not enough, you need to expand outward. It’s a very simple truth.

小太阳yy

wangerxian posted on 2022-5-11 16:47 If the maximum memory of MCU cannot meet the demand, it must be expanded externally. Moreover, as the product functions increase, the code will also occupy the MCU's Flash. Taking into account some products...

OK, thanks for the explanation

小太阳yy

littleshrimp posted on 2022-5-11 16:12 EELROM can store some frequently read and written content, such as TV channel switching =image=, while the MCU's FLASH has a relatively small number of erase and write times.

OK OK

小太阳yy

wangerxian posted on 2022-5-11 16:47 If the maximum memory of MCU cannot meet the demand, it must be expanded externally. Moreover, as the product functions increase, the code will also occupy the MCU's Flash. Taking into account some products...

So suppose I need to store a program with a large memory in the MCU. Can I choose an MCU with a very small memory and a very large EEPROM? In this case, doesn't it mean I don't need to choose an MCU with a large memory, and just adding an EEPROM will be a big deal?

wangerxian

wangerxian posted on 2022-5-11 16:47 If the maximum memory of MCU cannot meet the needs, it must be expanded externally. Moreover, as the product functions increase, the code will also occupy the Flash of MCU. Considering comprehensively, some products...

Suppose I need a program with a large memory to be stored in MCU, can I choose an MCU with a small memory and a large EEPROM? In this case, don’t I need to choose an MCU with a large memory? Just increasing the EEPROM is not enough?

Yes, but you have to use flash.

Fred_1977

This is a design selection issue. If you know in the early design that the program memory is relatively large, you can use a large-capacity Flash version MCU.

Gen_X

Support everyone's opinion!

One use we often see is copyright and "confidential data". Board production cannot be controlled, and piracy is common. If some confidential data or temporary important data are stored separately, and a dedicated person installs and provides it when the whole machine leaves the factory, it will limit the unplanned parallel import of products. Because only a few people have these data, and each one is related to the user and the contract, it ensures the traceability of production and subsequent services.

In addition, some data are frequently rewritten and have to be stored externally even if the data is small, such as the car's mileage and vehicle computer status data.

vincentc543

Some MCUs cannot read and write internal FLASH, but if there is a need for memory, an external EEPROM is required.

Sometimes the MCU is not big enough to store audio or pictures, so it will be stored in an external large-capacity EEPROM or FLASH.

Sometimes, a special EEPROM is placed for encryption to protect the program, and the company's special code is burned in it.

Sometimes the MCU is designed in such a way that the program is loaded from an external EEPROM and executed.

There are many situations, but they all have their purpose.

RichSJ

The internal settings of MCU are becoming more and more complicated, such as DCDC output voltage, maximum protection current, LDO output voltage, GPIO settings. MCU manufacturers used EEPROM or FLASH to store the internal information mentioned above, sometimes including the factory batch number, plus the preset parameters I mentioned here, which manufacturers usually call OTP (One time program).

RichSJ

Sorry, my bad, I mean MPU