Posted on October 01, 2008 at 11:18 Hi.
I’m working on the STR750 eval board for a new project, and have some trouble with the PLL. It doesn’t seem like the clock changes from 4 MHz when I multiply the clock.
The interrupt should toggle a LED about 7.5Hz but instead the frequency is 0.5 Hz.If I change CKSYS to 4 MHz instead of 15x4Mhz the frequency doesn’t change.
My configuration:
void SystemSetup(void)
{
//MRCC system reset
MRCC_DeInit();
//Wait for OSC4M start-up
OSC4MStartUpStatus = MRCC_WaitForOSC4MStartUp();
if(OSC4MStartUpStatus == SUCCESS)
{
// Set HCLK to 60 MHz
MRCC_HCLKConfig(MRCC_CKSYS_Div1);
// Set CKTIM to 60 MHz
MRCC_CKTIMConfig(MRCC_HCLK_Div1);
// Set PCLK to 60 MHz
MRCC_PCLKConfig(MRCC_CKTIM_Div1);
// Enable Flash burst mode
CFG_FLASHBurstConfig(CFG_FLASHBurst_Enable);
// Set CKSYS to 60 MHz
MRCC_CKSYSConfig(MRCC_CKSYS_OSC4MPLL, MRCC_PLL_Mul_15);
}
//GPIO pins optimized for 5V operation
MRCC_IOVoltageRangeConfig(MRCC_IOVoltageRange_5V);
//Enable Timer 1, UART0 and GPIO Clocks
MRCC_PeripheralClockConfig(MRCC_Peripheral_TIM0 | MRCC_Peripheral_UART0 | MRCC_Peripheral_GPIO, ENABLE);
}
And my timer setup:
void initTimer(void)
{
/* TIM Configuration in Output Compare Timing Mode ---------------------------*/
/* CK_TIM = 60 MHz, Prescaler = 4093, TIM0_CLK = CK_TIM/(Prescaler + 1) = 656 KHz */
/* Period = 19 TIM0 Update event frequency = TIM0_CLK/ (TIM_Period+1) = 7.5 Hz */
TIM_InitStructure.TIM_Mode = TIM_Mode_OCTiming;
TIM_InitStructure.TIM_Prescaler = 4093;
TIM_InitStructure.TIM_ClockSource = TIM_ClockSource_Internal;
TIM_InitStructure.TIM_CounterMode = TIM_CounterMode_Down;
TIM_InitStructure.TIM_Channel = TIM_Channel_1;
TIM_InitStructure.TIM_Period = 1953;
TIM_Init(TIM0, &TIM_InitStructure);
/* Clear TIM0 flags */
TIM_ClearFlag(TIM0, TIM_FLAG_OC1| TIM_FLAG_OC2| TIM_FLAG_Update);
/* Enable TIM0 Update interrupt */
TIM_ITConfig(TIM0, TIM_IT_Update, ENABLE);
/* Enable TIM0 counter */
TIM_Cmd(TIM0, ENABLE);
}
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Attachments : TIM.zip :
https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006HtO9&d=%2Fa%2F0X0000000aPJ%2FaIhFvgrZscz8wNEVnmiSt4Hc.D8V16BhZPx9lo1WW_M&asPdf=false
