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author | James McKenzie <git@madingley.org> | 2015-08-03 10:34:07 +0100 |
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committer | James McKenzie <git@madingley.org> | 2015-08-03 10:34:07 +0100 |
commit | 061430973e82995368d27ff9081391f9475da3c7 (patch) | |
tree | 62ac12e6cff789050ca17f00ac70d85de75e3efd /include | |
parent | 23e5d273ef3e11c8ad463c632daa5a52684bc5bb (diff) | |
download | candlestick-061430973e82995368d27ff9081391f9475da3c7.tar.gz candlestick-061430973e82995368d27ff9081391f9475da3c7.tar.bz2 candlestick-061430973e82995368d27ff9081391f9475da3c7.zip |
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Diffstat (limited to 'include')
-rw-r--r-- | include/stm32f101cb_clock.h | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/include/stm32f101cb_clock.h b/include/stm32f101cb_clock.h new file mode 100644 index 0000000..0fc8a33 --- /dev/null +++ b/include/stm32f101cb_clock.h @@ -0,0 +1,66 @@ +#include <libopencm3/stm32/rcc.h> +#include <libopencm3/stm32/flash.h> + +static inline void rcc_clock_setup_in_hse_8mhz_out_48mhz(void) +{ + /* The part says SYSCLK < 36MHz, but to get usb we need */ + /* sysclk == 48MHz or 72MHz */ + + + /* Enable internal high-speed oscillator. */ + rcc_osc_on(HSI); + rcc_wait_for_osc_ready(HSI); + + /* Select HSI as SYSCLK source. */ + rcc_set_sysclk_source(RCC_CFGR_SW_SYSCLKSEL_HSICLK); + + /* Enable external high-speed oscillator 8MHz. */ + rcc_osc_on(HSE); + rcc_wait_for_osc_ready(HSE); + rcc_set_sysclk_source(RCC_CFGR_SW_SYSCLKSEL_HSECLK); + + /* + * Set prescalers for AHB, ADC, ABP1, ABP2. + * Do this before touching the PLL (TODO: why?). + */ + rcc_set_hpre(RCC_CFGR_HPRE_SYSCLK_DIV2); /* Set. 24MHz Max. 36MHz */ + rcc_set_adcpre(RCC_CFGR_ADCPRE_PCLK2_DIV4); /* Set. 12MHz Max. 14MHz */ + rcc_set_ppre1(RCC_CFGR_PPRE1_HCLK_NODIV); /* Set. 24MHz Max. 36MHz */ + rcc_set_ppre2(RCC_CFGR_PPRE2_HCLK_NODIV); /* Set. 24MHz Max. 36MHz */ + rcc_set_usbpre(RCC_CFGR_USBPRE_PLL_CLK_NODIV); /* Set. 48Mhz Max. 48Mhz */ + + /* + * Sysclk runs with 36MHz -> 1 waitstates. + * 0WS from 0-24MHz + * 1WS from 24-48MHz + * 2WS from 48-72MHz + */ + flash_set_ws(FLASH_ACR_LATENCY_1WS); + + /* + * Set the PLL multiplication factor to 3. + * 8MHz (external) * 6 (multiplier) = 48MHz + */ + rcc_set_pll_multiplication_factor(RCC_CFGR_PLLMUL_PLL_CLK_MUL6); + + /* Select HSE as PLL source. */ + rcc_set_pll_source(RCC_CFGR_PLLSRC_HSE_CLK); + + /* + * Don't Divide external frequency by 2 before entering PLL + * (only valid/needed for HSE). + */ + rcc_set_pllxtpre(RCC_CFGR_PLLXTPRE_HSE_CLK); + + /* 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(RCC_CFGR_SW_SYSCLKSEL_PLLCLK); + + /* Set the peripheral clock frequencies used */ + rcc_ahb_frequency = 24000000; + rcc_apb1_frequency = 24000000; + rcc_apb2_frequency = 24000000; +} |