Posted on February 08, 2014 at 05:25
This pulse train is generated with the following code
This pulse train was created with the following code.
Could somebody help me to determine why my board is running at third of the speed. I am using emBlocks IDE and STM32F429I-Discovery_FW_V1.0.1 library. The loader code calls SystemInit (row 337 in system_stm32F4xx.c), which calls SetSysClock (row 470) executing rows 533-5 This confirms that the speed should be 180 MHz.
#if defined (STM
32
F
427
_
437
xx) || defined (STM
32
F
429
_
439
xx)
/* Enable the Over-drive to extend the clock frequency to 180 Mhz */
PWR->CR |= PWR_CR_ODEN;
while((PWR->CSR & PWR_CSR_ODRDY) ==
0
)
{
}
PWR->CR |= PWR_CR_ODSWEN;
while((PWR->CSR & PWR_CSR_ODSWRDY) ==
0
)
{
}
/* Configure Flash prefetch, Instruction cache, Data cache and wait state */
FLASH->ACR = FLASH_ACR_PRFTEN | FLASH_ACR_ICEN |FLASH_ACR_DCEN |FLASH_ACR_LATENCY_
5
WS;
#endif
/* STM32F427_437x || STM32F429_439xx */#include <stm
32
f
4
xx.h>
#include <stm
32
f
4
_init.h>
int main(void)
{
RCC->AHB
1
ENR |= RCC_AHB
1
ENR_GPIOCEN; // Enable GPIOC clock
GPIOC->MODER = GPIO_Mode_OUT <<(
2
*
13
); // Configure PC
13
GPIOC->OTYPER = GPIO_OType_PP <<(
2
*
13
); // ignore other pins
GPIOC->OSPEEDR = GPIO_Speed_
100
MHz <<(
2
*
13
);
GPIOC->PUPDR = GPIO_PuPd_NOPULL <<(
2
*
13
);
while (
1
) {
GPIOC->BSRRL = GPIO_BSRR_BS_
13
; // Set PC
13
GPIOC->BSRRH = GPIO_BSRR_BS_
13
; // Clear PC
13
GPIOC->BSRRL = GPIO_BSRR_BS_
13
;
GPIOC->BSRRH = GPIO_BSRR_BS_
13
;
GPIOC->BSRRL = GPIO_BSRR_BS_
13
;
GPIOC->BSRRH = GPIO_BSRR_BS_
13
;
GPIOC->BSRRL = GPIO_BSRR_BS_
13
;
GPIOC->BSRRH = GPIO_BSRR_BS_
13
;
GPIOC->BSRRL = GPIO_BSRR_BS_
13
;
GPIOC->BSRRH = GPIO_BSRR_BS_
13
;
}
}080002FE strh r3, [r2, #24]
08000300 strh r3, [r2, #26]
08000302 strh r3, [r2, #24]
08000304 strh r3, [r2, #26]
08000306 strh r3, [r2, #24]
08000308 strh r3, [r2, #26]
0800030A strh r3, [r2, #24]
0800030C strh r3, [r2, #26]
0800030E strh r3, [r2, #24]
08000310 strh r3, [r2, #26]
08000312 b.n 0x80002fe <
main
+50>#include <stm
32
f
4
xx.h>
#include <stm
32
f
4
_init.h>
#def
ine oneMilliSecond
180
*
1000
int main(void)
{
uint
32
_t triggerLimit=
0
;
uint
32
_t loopCount=
0
;
RCC->AHB
1
ENR |= RCC_AHB
1
ENR_GPIOCEN; // Enable GPIOC clock
GPIOC->MODER = GPIO_Mode_OUT <<(
2
*
13
); // Configure PC
13
GPIOC->OTYPER = GPIO_OType_PP <<(
2
*
13
); // ignore other pins
GPIOC->OSPEEDR = GPIO_Speed_
100
MHz <<(
2
*
13
);
GPIOC->PUPDR = GPIO_PuPd_NOPULL <<(
2
*
13
);
CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk; // Enable core debugger for tracing
DWT->CYCCNT =
0
; // Reset debugger trace
counter
DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk; // Enable cycle
counter
while (
1
) {
if (DWT->CYCCNT > triggerLimit) {
triggerLimit += oneMilliSecond;
loopCount++;
if (loopCount &
1
) {
GPIOC->BSRRL = GPIO_BSRR_BS_
13
; // Set PC
13
} else {
GPIOC->BSRRH = GPIO_BSRR_BS_
13
; // Clear PC
13
}
}
}
}08000320 ldr r3, [r1, #4]
08000322 cmp r2, r3
08000324 bcs.n 0x8000320 <
main
+84>
08000326 adds r0, #1
08000328 lsls r3, r0, #31
0800032A add.w r2, r2, #179200 ; 0x2bc00
0800032E add.w r2, r2, #800 ; 0x320
08000332 ite mi
08000334 strhmi r4, [r5, #24]
08000336 strhpl r4, [r5, #26]
08000338 b.n 0x8000320 <
main
+84>
