mirror of
https://github.com/cesanta/mongoose.git
synced 2024-12-04 18:29:01 +08:00
46 lines
1.9 KiB
C
46 lines
1.9 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 = CPU_FREQUENCY;
|
|
|
|
void SystemInit(void) { // Called automatically by startup code
|
|
SCB->CPACR |= ((3UL << 20U) | (3UL << 22U)); // Enable FPU
|
|
asm("DSB");
|
|
asm("ISB");
|
|
|
|
// Set flash latency. RM0481, section 7.11.1, section 7.3.4 table 37
|
|
SETBITS(FLASH->ACR, (FLASH_ACR_WRHIGHFREQ_Msk | FLASH_ACR_LATENCY_Msk),
|
|
FLASH_ACR_LATENCY_5WS | FLASH_ACR_WRHIGHFREQ_1);
|
|
|
|
if (ldo_is_on()) {
|
|
PWR->VOSCR = PWR_VOSCR_VOS_0 | PWR_VOSCR_VOS_1; // Select VOS0
|
|
} else {
|
|
PWR->VOSCR = PWR_VOSCR_VOS_1; // Select VOS1
|
|
}
|
|
uint32_t f = PWR->VOSCR; // fake read to wait for bus clocking
|
|
while ((PWR->VOSSR & PWR_VOSSR_ACTVOSRDY) == 0) spin(1);
|
|
(void) f;
|
|
RCC->CR = RCC_CR_HSION; // Clear HSI clock divisor
|
|
while ((RCC->CR & RCC_CR_HSIRDY) == 0) spin(1); // Wait until done
|
|
RCC->CFGR2 = (PPRE3 << 12) | (PPRE2 << 8) | (PPRE1 << 4) | (HPRE << 0);
|
|
RCC->PLL1DIVR =
|
|
((PLL1_P - 1) << 9) | ((PLL1_N - 1) << 0); // Set PLL1_P PLL1_N
|
|
// Enable P and Q divider outputs; set PLL1_M, select HSI as source,
|
|
// !PLL1VCOSEL, PLL1RGE=0
|
|
RCC->PLL1CFGR =
|
|
RCC_PLL1CFGR_PLL1QEN | RCC_PLL1CFGR_PLL1PEN | (PLL1_M << 8) | (1 << 0);
|
|
RCC->CR |= RCC_CR_PLL1ON; // Enable PLL1
|
|
while ((RCC->CR & RCC_CR_PLL1RDY) == 0) spin(1); // Wait until done
|
|
RCC->CFGR1 |= (3 << 0); // Set clock source to PLL1
|
|
while ((RCC->CFGR1 & (7 << 3)) != (3 << 3)) spin(1); // Wait until done
|
|
|
|
rng_init(); // Initialise random number generator
|
|
SysTick_Config(CPU_FREQUENCY / 1000); // Sys tick every 1ms
|
|
}
|