What modifications would be needed to work with STM32F091RC?

Try this version. It is based on code from the STM, for your Nucleo F091. Unfortunately I do not have the possibility to test this code.

Note that in the F091 flash pages are smaller than in the F401.
2KB which gives less than 1KB for variables.

Thanks, NS. I will test and report back... It works as is! I will try in my program...

QUESTION: Why does your printf work? For printing, I have to do: Serial pc(USBTX, USBRX);

..and then print with: pc.print()

QUESTION 2: How can I increase EEPROM emulation (flash) size? I need more than 2 pages. (2KB) The app not AN4061 says it should be done, but not how.

1. This version of the printf function works much like the class method Serial. It operates at Nucleo F091 on default parameters, ie. USBTX, USBRX 9600.
It should work. If this does not work, use the Serial class.

2. In this program here above(00_eeprom_emulation_f091) I added the possibility of increasing the size of EEPROM. Download the new version.
I have not tested this on the F091. But a similar program (in F030 flash pages are smaller than the F091) I have tested at Nucleo F030 and works well.

Thanks, NS!

I will set NB_OF_VAR to the number of 16-bit variables that I need for storage (eg. 1000), right? And so VirtAddVarTab[NB_OF_VAR] must have 1000 elements, that is: VirtAddVarTab[1000] = { 1, 2, 3, ..., 999, 1000 }; Right?

What is maximum number (NB_OF_VAR) of 16-bit variables ? 65535?

Yes. If you need to increase this variable (in eeprom.h), then at the same time increase the number of array elements in VirtAddVarTab.
Although NB_OF_VAR is declared in #define macro as uint8_t, I suspect that you can use numbers range 1 ... 32768.
But the main limitation is the size of the "virtual" page ie. number of variables is the size of "virtual" page (in bytes) divided by four.
Where the virtual page size, is the size of flash pages multiplied by PAGE_NB_PVP. What can you change.

I set EEPROM_START_ADDRESS and PAGE0.. = ADDR_FLASH_PAGE_118 and PAGE1_.. to ADDR_FLASH_PAGE_121 to move flash data away from code. NB_OF_VAR = 1000 reads and writes 1000 words ok. But NB_OF_VAR = 2000 fails

If you do not have not changed PAGE_NB_PVP = 4, then page1 should start from (at least) ADDR_FLASH_PAGE_122, not 121.

PAGE0 - flash page 118,119,120,121
PAGE1 - Flash pages 122,123,124,125

With NB_OF_VAR = 1000, all works ok.. no delays. Writing takes a second or two. With NB_OF_VAR = 2000, then writing takes 2-3 minutes, using EE_WriteVariable.

Here is my eeprom.h ....................................

define PAGE_NB_PVP ((uint32_t) 4)

define PAGE_SIZE ((uint32_t)FLASH_PAGE_SIZE * PAGE_NB_PVP) /* Page size */

define EEPROM_START_ADDRESS ((uint32_t)ADDR_FLASH_PAGE_118)

define PAGE0_BASE_ADDRESS ((uint32_t)(EEPROM_START_ADDRESS + 0x0000)) define PAGE0_END_ADDRESS ((uint32_t)(EEPROM_START_ADDRESS + (PAGE_SIZE - 1)))

define PAGE1_BASE_ADDRESS ((uint32_t)(ADDR_FLASH_PAGE_122)) define PAGE1_END_ADDRESS ((uint32_t)(ADDR_FLASH_PAGE_122 + PAGE_SIZE - 1))

/* Used Flash pages for EEPROM emulation */ define PAGE0 ((uint16_t)0x0000) define PAGE1 ((uint16_t)((PAGE1_BASE_ADDRESS-PAGE0_BASE_ADDRESS)/PAGE_SIZE)) /* Page nb between PAGE0_BASE_ADDRESS &

PAGE1_BASE_ADDRESS*/

/* No valid page define */ define NO_VALID_PAGE ((uint16_t)0xFFFF)

/* Page status definitions */ define ERASED ((uint16_t)0xFFFF) /* Page is empty */ define RECEIVE_DATA ((uint16_t)0xEEEE) /* Page is marked to receive data */ define VALID_PAGE ((uint16_t)0x0000) /* Page containing valid data */

/* Valid pages in read and write defines */ define READ_FROM_VALID_PAGE ((uint8_t)0x00) define WRITE_IN_VALID_PAGE ((uint8_t)0x01)

/* Page full define */ define PAGE_FULL ((uint8_t)0x80)

/* Variables' number */ define NB_OF_VAR ( 2000 )

I tried to create a situation like yours, but I don't have the F091. I did tests on the Nucleo-F030 (the only difference is a different flash page size) using this program:

#include "mbed.h"
#include "eeprom.h"


Timer t;

uint16_t VirtAddVarTab[NB_OF_VAR];


int main()
{
    int i;

    printf("\n\n*** EEPROM test ***\n");
    printf("NB_OF_VAR=%d, PAGE_SIZE=%d, FLASH_PAGE_SIZE=%d\n\n",
           NB_OF_VAR,PAGE_SIZE,FLASH_PAGE_SIZE);

    for (i=0; i<NB_OF_VAR; i++) {
        VirtAddVarTab[i]=i;
    } // virtual addreses in sequence 0..NB_OF_VAR-1

    printf("EEPROM init  ");
    t.reset();
    t.start();
    /* Unlock the Flash Program Erase controller */
    HAL_FLASH_Unlock();
    EE_Init();
    t.stop();
    printf("- time used= %f seconds\n", t.read());


    printf("First writing (all variables)  ");
    t.reset();
    t.start();
    for (i=0; i<NB_OF_VAR; i++) {
        EE_WriteVariable(VirtAddVarTab[i], 10000+i);
    } //
    t.stop();
    printf("- time used= %f seconds\n", t.read());

    printf("Second writing (all variables)  ");
    t.reset();
    t.start();
    for (i=0; i<NB_OF_VAR; i++) {
        EE_WriteVariable(VirtAddVarTab[i], 20000+i);
    } //
    t.stop();
    printf("- time used= %f seconds\n", t.read());

    printf("Third writing (all variables)  ");
    t.reset();
    t.start();
    for (i=0; i<NB_OF_VAR; i++) {
        EE_WriteVariable(VirtAddVarTab[i], 30000+i);
    } //
    t.stop();
    printf("- time used= %f seconds\n", t.read());

    printf("The end.\n");
}

where I used 2,000 variables and size of virtual page 8kB.
Results:

*** EEPROM test ***
NB_OF_VAR=2000, PAGE_SIZE=8192, FLASH_PAGE_SIZE=1024

EEPROM init  - time used= 0.001267 seconds
First writing (all variables)  - time used= 0.700537 seconds
Second writing (all variables)  - time used= 2.010621 seconds
Third writing (all variables)  - time used= 0.964252 seconds
The end.


*** EEPROM test ***
NB_OF_VAR=2000, PAGE_SIZE=8192, FLASH_PAGE_SIZE=1024

EEPROM init  - time used= 0.000498 seconds
First writing (all variables)  - time used= 0.964254 seconds
Second writing (all variables)  - time used= 0.964421 seconds
Third writing (all variables)  - time used= 0.964248 seconds
The end.

The first pass is after flashing the program, when the EEPROM is uninitialized. The second after the reset.

Therefore, I don't know what might be in your case, that you have such long writing times (minutes).

not big enough