Content originally posted in LPCWare by krzysztofciesluk on Thu Sep 20 01:57:51 MST 2012
Hello,
I have lpc1225 and System Oscillator 14,7456 MHz.
I enable 2 cycle reads for high frequency operation
LPC_FLASHCTRL->FLASHCFG = 0;
LPC_SYSCON->PRESETCTRL &= ~(1<<15);
/* Wait 200us for OSC to be stablized, no status indication, dummy wait. */
for (i = 0; i < 200; i++) __NOP();
next I set System oscillator as PLL input
REG_SYSCON_SYSPLLCLKSEL = PLL_CLK_SEL_SYS_OSC;
REG_SYSCON_SYSPLLCLKUEN |= PLL_CLK_ENA_UPDATE;
REG_SYSCON_SYSPLLCLKUEN &= ~PLL_CLK_ENA_UPDATE;
REG_SYSCON_SYSPLLCLKUEN |= PLL_CLK_ENA_UPDATE;
while (!(REG_SYSCON_SYSPLLCLKUEN & PLL_CLK_ENA_UPDATE));
for (i = 0; i < 200; i++) __NOP();
next I set M = 3 and P = 2
F(CLKOUT) = 44,2368 MHz = (3 * 14,7456 MHz) = (176.9472 MHz / (2 * 2))
REG_SYSCON_SYSPLLCTRL = (1<<5) |(2<<0);
REG_SYSCON_PDRUNCFG &= ~PDRUNCFG_SYSPLL_PD;
while (!(REG_SYSCON_SYSPLLSTAT & PLL_LOCK));
for (i = 0; i < 200; i++) __NOP();
now I select main clock = pll output
REG_SYSCON_MAINCLKSEL = MAIN_CLK_SEL_PLL_OUT;
REG_SYSCON_MAINCLKUEN |= MAIN_CLK_UPDATE_ENA;
REG_SYSCON_MAINCLKUEN &= ~MAIN_CLK_UPDATE_ENA;
REG_SYSCON_MAINCLKUEN |= MAIN_CLK_UPDATE_ENA;
while (!(REG_SYSCON_MAINCLKUEN & MAIN_CLK_UPDATE_ENA));
for (i = 0; i < 200; i++) __NOP();
And it don't work. I get HardFault or MEM error.
But when i Power-up SYSPLL at the begining of code (after set 2 cycle read) it work
LPC_FLASHCTRL->FLASHCFG = 0;
LPC_SYSCON->PRESETCTRL &= ~(1<<15);
for (i = 0; i < 200; i++) __NOP();
REG_SYSCON_PDRUNCFG &= ~PDRUNCFG_SYSPLL_PD;
while (!(REG_SYSCON_SYSPLLSTAT & PLL_LOCK));
REG_SYSCON_SYSPLLCLKSEL = PLL_CLK_SEL_SYS_OSC;
REG_SYSCON_SYSPLLCLKUEN |= PLL_CLK_ENA_UPDATE;
REG_SYSCON_SYSPLLCLKUEN &= ~PLL_CLK_ENA_UPDATE;
REG_SYSCON_SYSPLLCLKUEN |= PLL_CLK_ENA_UPDATE;
while (!(REG_SYSCON_SYSPLLCLKUEN & PLL_CLK_ENA_UPDATE));
for (i = 0; i < 200; i++) __NOP();
REG_SYSCON_SYSPLLCTRL = (1<<5) |(2<<0);
while (!(REG_SYSCON_SYSPLLSTAT & PLL_LOCK));
for (i = 0; i < 200; i++) __NOP();
REG_SYSCON_MAINCLKSEL = MAIN_CLK_SEL_PLL_OUT;
REG_SYSCON_MAINCLKUEN |= MAIN_CLK_UPDATE_ENA;
REG_SYSCON_MAINCLKUEN &= ~MAIN_CLK_UPDATE_ENA;
REG_SYSCON_MAINCLKUEN |= MAIN_CLK_UPDATE_ENA;
while (!(REG_SYSCON_MAINCLKUEN & MAIN_CLK_UPDATE_ENA));
for (i = 0; i < 200; i++) __NOP();
Is it ok to use that order? Or is it possible that on some board on my desk it will work but on another 100 devices it will not work correct?
