diff options
Diffstat (limited to 'wirish/stm32f2/boards_setup.cpp')
| -rw-r--r-- | wirish/stm32f2/boards_setup.cpp | 32 |
1 files changed, 25 insertions, 7 deletions
diff --git a/wirish/stm32f2/boards_setup.cpp b/wirish/stm32f2/boards_setup.cpp index b3c690c..e1bf1fd 100644 --- a/wirish/stm32f2/boards_setup.cpp +++ b/wirish/stm32f2/boards_setup.cpp @@ -28,11 +28,18 @@ * @file wirish/stm32f2/boards_setup.cpp * @author Marti Bolivar <mbolivar@leaflabs.com> * @brief STM32F2 chip setup. + * + * This file controls how init() behaves on the STM32F2. Be very + * careful when changing anything here. Many of these values depend + * upon each other. */ -#include <libmaple/rcc.h> +#include "boards_private.h" + #include <libmaple/gpio.h> +#include <wirish/wirish_types.h> +// PLL configuration for 25 MHz external oscillator --> 120 MHz SYSCLK. #define PLL_Q 5 #define PLL_P 2 #define PLL_N 240 @@ -41,7 +48,18 @@ static stm32f2_rcc_pll_data pll_data = {PLL_Q, PLL_P, PLL_N, PLL_M}; namespace wirish { namespace priv { - rcc_pll_cfg board_pll_cfg = {RCC_PLLSRC_HSE, &pll_data}; + // PLL clocked off of HSE, with above configuration data. + rcc_pll_cfg w_board_pll_cfg = {RCC_PLLSRC_HSE, &pll_data}; + // As f_APB2 = 60 MHz (see board_setup_clock_prescalers), + // we need f_ADC = f_PCLK2 / 2 to get the (maximum) + // f_ADC = 30 MHz. + adc_prescaler w_adc_pre = ADC_PRE_PCLK2_DIV_2; + // With clocks as specified here (i.e. f_ADC = 30 MHz), this + // ADC sample rate allows for error less than 1/4 LSB with a + // 50 KOhm input impedance, assuming an internal sample and + // hold capacitance C_ADC at most 8.8 pF. See Equation 1 and + // Table 61 in the F2 datasheet for more details. + adc_smp_rate w_adc_smp = ADC_SMPR_144; void board_reset_pll(void) { // Set PLLCFGR to its reset value. @@ -49,8 +67,13 @@ namespace wirish { } void board_setup_clock_prescalers(void) { + // With f_SYSCLK = 120 MHz (as determined by board_pll_cfg), + // + // f_AHB = f_SYSCLK / 1 = 120 MHz rcc_set_prescaler(RCC_PRESCALER_AHB, RCC_AHB_SYSCLK_DIV_1); + // f_APB1 = f_AHB / 4 = 30 MHz rcc_set_prescaler(RCC_PRESCALER_APB1, RCC_APB1_HCLK_DIV_4); + // f_APB2 = f_AHB / 2 = 60 MHz rcc_set_prescaler(RCC_PRESCALER_APB2, RCC_APB2_HCLK_DIV_2); } @@ -58,10 +81,6 @@ namespace wirish { gpio_init_all(); } - void board_setup_adc(void) { - // TODO - } - void board_setup_timers(void) { // TODO } @@ -72,4 +91,3 @@ namespace wirish { } } - |