[Solved] How to use persistant vars in EEPROM

DavidZemon · 2014-09-22 18:35

Hello all,

I could pick a random large number for the variable address and hardcode it to a pointer... but I'd like to know if there is a better way to persistently read from and write to a variable in EEPROM. I only need to 16 bits, so a full filesystem on an SD card seems like a bit of overkill. Any ideas?

Thanks,
David

Electrodude · 2014-09-22 19:13

Write the variable to its RAM address in EEPROM - next boot, its new value will get loaded and not the 0 that used to be in the EEPROM.

Using Chris Gadd's "I2C driver.spin" as an example:

I2C.write_page(I2C#EEPROM,@val,val, 4)  ' long
I2C.write_page(I2C#EEPROM,@val,val, 2)  ' word
I2C.write(I2C#EEPROM,@val,val)  ' byte

If you're using C, it should be pretty similar, but I would probably make the variable volatile.

Volatile just means don't optimize this out, right?

DavidZemon · 2014-09-22 19:57

That looks great! I'll look into this

pmrobert · 2014-09-23 11:20

This is what I use.

/* Serial get/send integer routines */
    void send_int(int32_t z) {
        char b;
        b = z>>24;
        fdserial_txChar(serial,b);
        b = z>>16;
        fdserial_txChar(serial,b);
        b = z>>8;
        fdserial_txChar(serial,b);
        b = z;
        fdserial_txChar(serial,b);
    }

    int32_t get_int(void) {
        char b;
        int32_t result;
        result = 0;
        b = fdserial_rxChar(serial);
        result = b<<24;
        b = fdserial_rxChar(serial);
        result = result + (b<<16);
        b = fdserial_rxChar(serial);
        result = result + (b<<8);
        b = fdserial_rxChar(serial);
        result = result + b;
        return result;
    }

    /* target: 1=fuel, 2=ign, 3=afr, 4 = CLTCOMP, 5 = MATCOMP, more to come */
    /* op: 1 = EEPROM to mem, 2 = mem to EEPROM, 3 = mem to app, 4 = app to mem */
    /* 5 = get PIFlow/SIFlow 6 = send PIFlow/SIFlow */
    void DataShuttle(int target, int op) {
        int row,col;
        switch (target) {

        case 1 :
            for (row = 0; row < FUELBASEYSIZE; row++ )
                for (col = 0; col < FUELBASEXSIZE; col++ )
                    if (op == 1) { //EE2Mem
                        FuelBaseTable[col][row]=ee_getInt(FuelBaseTableOrg+(row*FUELBASEXSIZE*4)+(col*4));
                    } else if (op == 2) { //Mem2EE
                        ee_putInt(FuelBaseTable[col][row],FuelBaseTableOrg+(row*FUELBASEXSIZE*4)+(col*4));
                    } else if (op == 3) {
                        send_int(FuelBaseTable[col][row]);
                    } else if(op == 4) {
                        FuelBaseTable[col][row] = get_int();
                    }

            for (col = 0; col < FUELBASEXSIZE; col++ )
                if (op == 1) {
                    FuelBaseXAxis[col]=ee_getInt(FuelBaseXAxisOrg+(col*4));
                } else if (op == 2) {
                    ee_putInt(FuelBaseXAxis[col],FuelBaseXAxisOrg+(col*4));
                } else if (op == 3) {
                    send_int(FuelBaseXAxis[col]);
                } else if (op == 4) {
                    FuelBaseXAxis[col] = get_int();
                }

            for (row = 0; row < FUELBASEYSIZE; row++ )
                if (op == 1) {
                    FuelBaseYAxis[row]=ee_getInt(FuelBaseYAxisOrg+(row*4));
                } else if (op == 2) {
                    ee_putInt(FuelBaseYAxis[row],FuelBaseYAxisOrg+(row*4));
                } else if (op == 3) {
                    send_int(FuelBaseYAxis[row]);
                } else if (op == 4) {
                    FuelBaseYAxis[row] = get_int();
                }

            break;

/* Fuel Base Table */
#define FUELBASEXSIZE 16
#define FUELBASEYSIZE 16
volatile int32_t FuelBaseTable[FUELBASEXSIZE][FUELBASEYSIZE]; // 1024 bytes
volatile int32_t FuelBaseTableOrg = 32768; // 0x8000
volatile int32_t FuelBaseXAxis[FUELBASEXSIZE];
volatile int32_t FuelBaseXAxisOrg = 33792;
volatile int32_t FuelBaseYAxis[FUELBASEYSIZE];
volatile int32_t FuelBaseYAxisOrg = 33856;
volatile int32_t FuelCellVal;

DavidZemon · 2014-09-23 17:31

OH! ee_put* functions are in Simple! That's great

For anyone else stumbling across this thread, there are lots of ee_put* functions - there's one for byte, another for strings, etc.

All can be found in the doxygen documentation of Simple. Here's a link to ee_putInt() though:
http://david.zemon.name/PropWare/simpletools_8h.html#adf44a20755432a25076e28e94b809264

[Solved] How to use persistant vars in EEPROM

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