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Original question:

TMS570LC4357: Questions regarding the FEE Configuration and writing data

TMS570LC4357: Questions about FEE setup and Virtual Sectors

Max Wittekind
Expert 1835 points
Part Number: TMS570LC4357

Hello Experts,

I have a few Question regarding the setup of the FEE driver and the purpose of the Virtual Sectors.

(Q1) Is there a certain point in the program where one would have to call TI_Fee_Init or is it enough to call TI_Fee_Init when I actualy need the EEPROM?

For some context: We want to use atleast 110kb of the FEE. When FEE is full we want to be able to overwrite some of the data.

(Q2) The driver requires 2 Virtual Sectores with 1 Sector beeing active. In some Forum posts it is mentioned that a virtual sector gets erased, when it is full and the driver switches to the second sector. Is this always the case or can we write Data to the first sector and to the second sector while still reading data from the first. And if the second sector is full can we start rewriting Blocks in the first sector without loosing the data in the seond sector?

(Q3) Since there seems to be no way to select a virtual sector by a driver function, I would guess that the purpose of the Virtual Sectors is to reduce number of write cycles per cell in the FEE. This would also mean, that usable FEE Space is less than 64kb. Is this correct?

Additional Questions regarding the Data Blocks

(Q4) If I configure a Data Block to be a size of 20 bytes, the driver rounds this up to be 24bytes correct?

Thank you and best regards,
Max

  • +1
    TI__Guru**** 192486 points

    Hi Max,

    Q1. The FEE_Init is called only once before you use the FEE to initialize the FEE module. TMS570LC43x has one emulated EEPROM (flash Bank 7), it's size is 128KB. The EEPROM is divided into two or more virtual sectors. Minimum two virtual sectors are required, so only 64KB can be used for your data plus headers for data blocks and virtual sector.

    Q2.

    Max Wittekind said:
    Is this always the case or can we write Data to the first sector and to the second sector while still reading data from the first. And if the second sector is full can we start rewriting Blocks in the first sector without loosing the data in the seond sector?

    After switching to the 2nd virtual sector, the 2nd virtual sector becomes Active, and the first sector is marked as "ready to erase" and will be erased any time in the background. You are not able to read and write data from/to the 1st virtual sector any more.

    Q3.

    Max Wittekind said:
    This would also mean, that usable FEE Space is less than 64kb. Is this correct?

    Yes, the maximum space you can use is 64MB ( for data payload (aligned to 8 bytes), header (24 bytes) of data blocks, and header (32 bytes) of the virtual sector).

    Q4.

    Max Wittekind said:
    If I configure a Data Block to be a size of 20 bytes, the driver rounds this up to be 24bytes correct?

    Yes. It is rounded up to n*8 bytes.