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Added rcc clock setup function for 16mhz crystal.

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This commit is contained in:
Thomas Otto 2010-05-02 20:20:04 +02:00
parent 8dc36291d1
commit 4f272b4ad4
2 changed files with 42 additions and 0 deletions
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1
include/libopenstm32/rcc.h
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@ -400,5 +400,6 @@ void rcc_set_hpre(u32 hpre);
u32 rcc_get_system_clock_source(int i);
void rcc_clock_setup_in_hsi_out_64mhz(void);
void rcc_clock_setup_in_hse_8mhz_out_72mhz(void);
void rcc_clock_setup_in_hse_16mhz_out_72mhz(void);
#endif

41
lib/rcc.c
View File

@ -424,3 +424,44 @@ void rcc_clock_setup_in_hse_8mhz_out_72mhz(void)
/* Select PLL as SYSCLK source. */
rcc_set_sysclk_source(SW_SYSCLKSEL_PLLCLK);
}
void rcc_clock_setup_in_hse_16mhz_out_72mhz(void)
{
/* enable Internal High Speed Oscillator */
rcc_osc_on(HSI);
rcc_wait_for_osc_ready(HSI);
/* Select HSI as SYSCLK source. */
rcc_set_sysclk_source(SW_SYSCLKSEL_HSICLK);
/* enable External High Speed Oscillator 16MHz */
rcc_osc_on(HSE);
rcc_wait_for_osc_ready(HSE);
rcc_set_sysclk_source(SW_SYSCLKSEL_HSECLK);
/* set prescalers for ADC, ABP1, ABP2... make this before touching the PLL */
rcc_set_hpre(HPRE_SYSCLK_NODIV); //prescales the AHB clock from the SYSCLK
rcc_set_adcpre(ADCPRE_PLCK2_DIV6); //prescales the ADC from the APB2 clock; max 14MHz
rcc_set_ppre1(PPRE1_HCLK_DIV2); //prescales the APB1 from the AHB clock; max 36MHz
rcc_set_ppre2(PPRE2_HCLK_NODIV); //prescales the APB2 from the AHB clock; max 72MHz
/* sysclk should run with 72MHz -> 2 Waitstates ; choose 0WS from 0-24MHz, 1WS from 24-48MHz, 2WS from 48-72MHz */
flash_set_ws(FLASH_LATENCY_2WS);
/* Set the PLL multiplication factor to 9. -> 16MHz (external) * 9 (multiplier) / 2 (PLLXTPRE_HSE_CLK_DIV2) = 72MHz */
rcc_set_pll_multiplication_factor(PLLMUL_PLL_CLK_MUL9);
/* Select HSI as PLL source. */
rcc_set_pll_source(PLLSRC_HSE_CLK);
/* divide external frequency by 2 before entering pll (only valid/needed for HSE) */
rcc_set_pllxtpre(PLLXTPRE_HSE_CLK_DIV2);
/* Enable PLL oscillator and wait for it to stabilize. */
rcc_osc_on(PLL);
rcc_wait_for_osc_ready(PLL);
/* Select PLL as SYSCLK source. */
rcc_set_sysclk_source(SW_SYSCLKSEL_PLLCLK);
}