Posted on May 07, 2007 at 08:14Hi hl,
I just tried with my board (Keil MCBSTR750). It has a 4Mhz external oszillator.
I configure the PLL on C-Level, using the API from ST (not in the assembler code). So far I used FlashBurst mode, because I am running at 60Mhz.
For you I tried to disable flash-burst mode, and divided HCLK by two to get 30Mhz (at least I expect this HCLK is used for accessing the flash). I did no detailed testing (I have no time, sorry). But seems, that didn't work very well -- the instruction pointer is somewhere, but not pointing to my program code.
By dividing by 4, the code seems to be executed -- at least the instruction pointer points to my program code after stopping debugger. Maybe exactly 30Mhz causes already problems and not 32 Mhz ?
Here is my C-Code startup.
/* in debug mode, the ST library needs to be initialized */
/* by calling ''debug()'' function */
#ifdef DEBUG
debug();
#endif
/* MRCC system reset */
MRCC_DeInit();
/****************************************************************************/
/* setup of PLL, pheripheral clock frequency and flash burst mode */
/****************************************************************************/
/* Wait for OSC4M start-up */
t_error = MRCC_WaitForOSC4MStartUp();
if(t_error == SUCCESS)
{
/* Set HCLK to 60MHz */
// MRCC_HCLKConfig(MRCC_CKSYS_Div1);
MRCC_HCLKConfig(MRCC_CKSYS_Div2); ////// TEST (crash)
// MRCC_HCLKConfig(MRCC_CKSYS_Div4); ////// TEST (seems to work)
/* Set CKTIM to 60MHz */
MRCC_CKTIMConfig(MRCC_HCLK_Div2);
/* Set PCLK to 30MHz */
MRCC_PCLKConfig(MRCC_CKTIM_Div1);
/* Enable Flash Burst mode */
// CFG_FLASHBurstConfig(CFG_FLASHBurst_Enable); //////test
/* Set CK_SYS to 60 MHz */
MRCC_CKSYSConfig(MRCC_CKSYS_OSC4MPLL, MRCC_PLL_Mul_15);
}
Maybe you can comment out the PLL startup in assembler and perform some tests with the C-PLL startup routine.
Hope this helps.
Regards
Andreas
