On 2019-11-09 09:29, Shivakumar R via Sdcc-user wrote:
> The SPL example does not mention anything about changing the values of
> the option bytes, but I see that in my STM8S003F3P6 chip(20 pin tssop) I
> need to set the AFR0 bit of OPT2 (as well as NOPT2) to use the TIM1Ch2
> alternate function.
> #define P6_OPT2 0x4803
> #define P6_NOPT2 0x4804
> #define P6_AFR0 0x01
> _SFR_(P6_OPT2) |= P6_AFR0;
> _SFR_(P6_NOPT2) &= ~P6_AFR0;
You need to unlock the option byte before you can write to it.
Here is what I use to enable the alternate function on STM8S105. It
should be the same for STM8S003.
Cheers,
-Richard
/******************************************************************************
*
* Set remapping for output channel 3 on STM8S105K
* in: 0 = no, 2 = yes
*/
static void set_remap(char val)
{
char cfg;
eeprom_unlock();
FLASH_CR2 = 0x80; /* enable option byte */
FLASH_NCR2 = 0x7f;
cfg = OPT2;
cfg &= 0xfd;
cfg |= val;
OPT2 = cfg;
NOPT2 = ~cfg;
eeprom_lock();
}
/******************************************************************************
*
* Unlock EEPROM for writing
* out: zero = fail
*/
#pragma disable_warning 59
char eeprom_unlock(void)
{
__asm
mov _FLASH_DUKR, #0xae
mov _FLASH_DUKR, #0x56
clr a
00001$:
dec a
jreq 00090$
btjf _FLASH_IAPSR, #3, 00001$
00090$:
__endasm;
}
/******************************************************************************
*
* Lock EEPROM from writing after write
*/
void eeprom_lock(void)
{
__asm
bres _FLASH_IAPSR, #3
__endasm;
}
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