30 lines
1.3 KiB
C
30 lines
1.3 KiB
C
// Copyright (c) 2023 Cesanta Software Limited
|
|
// All rights reserved
|
|
//
|
|
// This file contains essentials required by the CMSIS:
|
|
// uint32_t SystemCoreClock - holds the system core clock value
|
|
// SystemInit() - initialises the system, e.g. sets up clocks
|
|
|
|
#include "hal.h"
|
|
|
|
uint32_t SystemCoreClock = SYS_FREQUENCY;
|
|
|
|
void SystemInit(void) { // Called automatically by startup code
|
|
SCB->CPACR |= ((3UL << 10 * 2) | (3UL << 11 * 2)); // Enable FPU
|
|
asm("DSB");
|
|
asm("ISB");
|
|
FLASH->ACR |= FLASH_LATENCY | BIT(8) | BIT(9); // Flash latency, prefetch
|
|
RCC->PLLCFGR &= ~((BIT(17) - 1)); // Clear PLL multipliers
|
|
RCC->PLLCFGR |= (((PLL_P - 2) / 2) & 3) << 16; // Set PLL_P
|
|
RCC->PLLCFGR |= PLL_M | (PLL_N << 6); // Set PLL_M and PLL_N
|
|
RCC->CR |= BIT(24); // Enable PLL
|
|
while ((RCC->CR & BIT(25)) == 0) spin(1); // Wait until done
|
|
RCC->CFGR = (APB1_PRE << 10) | (APB2_PRE << 13); // Set prescalers
|
|
RCC->CFGR |= 2; // Set clock source to PLL
|
|
while ((RCC->CFGR & 12) == 0) spin(1); // Wait until done
|
|
|
|
RCC->APB2ENR |= RCC_APB2ENR_SYSCFGEN; // Enable SYSCFG
|
|
rng_init(); // Initialise random number generator
|
|
SysTick_Config(SystemCoreClock / 1000); // Sys tick every 1ms
|
|
}
|