esp8266 eeprom read crash

[ADJ7WTB]

Does any one know why exception 28 crash on esp8266. I write data to eeprom. But when I want to read it. The esp8266 crash.
My code:

#include <EEPROM.h>

Struct mydata{
  char ssid;
  char pass;};

void setup(){ 
Serial.begin(9600);
EEPROM.begin(4096);
Readeeprom();
}
void Readeeprom (){
const char* said;
const char* pass;

mydata Varcustom;

EEPROM.get(0, Varcustom);
//Exception 28 error begin here
Serial.println(Varcustom.ssid);// does not show this print
}

Any help??

[ADJ7WTB]

My write to eeprom code look like this

My code:

#include <EEPROM.h>
Struct mydata{
char ssid;
char pass;
};

void setup(){ 
Serial.begin(9600);
EEPROM.begin(4096);
WriteEeprom();
}
void WriteEeprom (){
mydata Varcustom = {"ssid","password"};
EEPROM.put(0, Varcustom);
}

The short simple version

[igrr]

This code doesn't look like it should work.
If you need to save strings to EEPROM, take a look at this example: https://github.com/tzapu/WiFiManager/blob/master/WiFiManager.cpp#L164-L194

[ADJ7WTB]

Thanks for reply.
According to arduino ide document it should work.
I tried converting string to char. Then write it to eeprom. Should work but it gives me the same error. Will look at that code anyways.

[igrr]

Your writing code is not well-formed because struct fields are chars, and you are initializing these fields with const char*. This is undefined behaviour in C++.

Reading code doesn't make sense (you are only reading a single character for ssid and single character for pass field), but it shouldn't crash. I modified your sample a bit (changed baud rate, changed Struct to struct, added a Serial.println to the end of setup function): https://gist.github.com/igrr/cfd5411dccb2c6764e41. It runs without issues on my side.

Edit: okay, i was wrong on the first part: this isn't undefined behaviour, it's just an implicit cast which usually does not what the programmer intends to do.

[ADJ7WTB]

Thanks for the help. Atleast it's not crashing.

[asetyde]

I think is not good idea , use "block function" for me is stable and best choice

void eeprom_read_block(uint8_t * data, uint32_t address, size_t len) {
int i;
for (i = 0; i < len; i++) {
data[i] = EEPROM.read(address + i);
}
}

void eeprom_write_block(uint8_t * data, uint32_t address, size_t len) {
int i;
for (i = 0; i < len; i++) {
EEPROM.write(address + i, data[i]);
}
EEPROM.commit();
}

[asetyde]

simple and full tested