Error writing to data EEPROM using @eeprom

bevenson · ‎2013-12-06

Posted on December 06, 2013 at 21:36

I have a STM8S207 board and I'm using STVD version 4.3.3 with the Cosmic compiler. I am trying to use the @eeprom directive for writing/reading the data EEPROM and my system hangs when I try to write the data. Here's what I've been trying so far.

#include <string.h>

#include ''stm8s.h''

#include ''stm8s_flash.h''

@eeprom s16 eeData;

s16 localData;

/* Read the data */

localData = eeData; // Works

/* Write the data, scenario 1 */

eeData = localData;

/* Write the data, scenario 2 */

eecpy(&eeData, &localData, 2);

In both cases, the system hangs on the instruction in which I attempt to write to eeData. When stopping with the debugger I see that it is stopped inside function c_eewrw (library function?) at the following instruction:

BTJF 0x505f, #2, 0xb155

Is there something else I need to do to get the system ready to write to data EEPROM?

Thanks,

Bryan

pierreandre · ‎2013-12-08

Posted on December 09, 2013 at 08:25

I work with STM8L, but it is probably equivalent.

I have to unlock the eeprom before writing it, but on 8L writing to a protected memory don't hang the CPU.

fggnrc2 · ‎2013-12-09

Posted on December 09, 2013 at 11:45

Bryan,

the instruction where your program hangs waits for the EEPROM programming end.

As Argail told you, if you don't unlock EEPROM by writing the sequence: 0xAE 0x56 in FLASH_DUKR, your code will wait forever.

Regards,

EtaPhi

bevenson · ‎2013-12-09

Posted on December 09, 2013 at 19:52

All,

Thanks for the help. Turns out I was doing a few things wrong. First, I had a typo in my call to _fctcpy, so the flash programming routines of mine were not loaded into RAM. Then, as mentioned, I had also forgotten to unlock EEPROM. Also, I am using an external osciallator that operates above 16 MHz, so I set OPT7 to add a wait state as suggested by the datasheet.

I also discovered that the data EEPROM gets cleared upon loading the program with the debugger. Makes sense, but I thought the debugger just re-wrote program flash, not the data EEPROM. Just restarting the debugger without stopping/starting the debugger does not re-write data EEPROM. Once I got all that straight I was able to write to data EEPROM and see my data still there upon a power cycle.

Thanks,

Bryan