![](/media/cache/profiles/f0fcf351df4eb6786e9bb6fc4e2dee02.jpg.50x50_q85.jpg)
Check System frequency of Nucleo F411RE board. Also F401RE.
<May 12th, 2015>
I have confirmed that both mbed lib. and mbed-src lib. have updated to change F411RE mbed System clock and USB clock as below.
fVCO = fPLL-in x (PLLN/PLLM), fPLL-out = fVCO/PLLP, fUSB-out = fVCO/PLLQ Use PLL with PLLN=192, PLLM=4 Use HSE(not Xtal but External Clock)=8000000Hz PLL/Base freq= 384000000Hz Use PLL with PLLP=4, PLLQ=8 PLL/System freq= 96000000Hz PLL/USB freq= 48000000Hz SYSCLK clock freq. = 96000000Hz HCLK clock freq. = 96000000Hz PCLK1 clock freq. = 48000000Hz PCLK2 clock freq. = 96000000Hz
mbed lib. Rev. -> 98 & mbed-src lib. Rev. ->539
We can use USB with proper colok!.
If you would like to use 100MHz System clock, please refer updated "Nucleo_F411RE_SysClk".
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I made a clock checking program for Nucleo F411RE and F401 mbed board.
Picture shows F411RE example.
System frequency is 100MHz. Looks okay for me.
USB frequency is 44.4MHz? -> USB clock needs accurate frequency 48MHz.
Once keeping 100MHz system clock freq., we can select PLLQ value only 9 or 8.
If PLLQ=9, USB Freq. is 44.4MHz (current setting).
If PLLQ=8, USB Freq. is 50.0MHz.
Best selection looks follows.
PLL clock -> HSE = 8MHz
PLLN= 192, PLLM = 4
PLL Freq. = (PLL Clock)*(PLLN/PLLM) = 8MHz * 192 / 4 = 384MHz
System clock = (PLL Freq.)/PLLP = 384MHz/4 = 96MHz
USB clock = (PLL Freq.)/PLLQ = 384MHz/8 = 48MHz
Is this result okay?
or
Is my program wrong?
Diff: main.cpp
- Revision:
- 1:2d6d2ccd87f8
- Parent:
- 0:0766e37fd3d6
--- a/main.cpp Sun Nov 02 04:58:59 2014 +0000 +++ b/main.cpp Sun Nov 02 05:11:28 2014 +0000 @@ -13,6 +13,7 @@ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ +#if defined(TARGET_NUCLEO_F401RE) || defined(TARGET_NUCLEO_F411RE) #include "mbed.h" @@ -224,6 +225,9 @@ c = GETC(); PUTC(c); cpu_freq(); + put_rn(); + PRINTF("Repeat -> push RESET button"); + put_rn(); while(1) { myled = 1; // LED is ON wait(0.2); // 200 ms @@ -231,3 +235,7 @@ wait(1.0); // 1 sec } } + +#else +#warning "This is only for mbed Nucleo F411RE & F401RE +#endif