system.c

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/*
 * Copyright (c) 2017, James Jackson
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 *
 * * Neither the name of the copyright holder nor the names of its
 *   contributors may be used to endorse or promote products derived from
 *   this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "system.h"

// current uptime for 32kHz systick timer. will rollover after 1.5 days. hopefully we won't care.
static volatile uint64_t sysTickUptime = 0;

// SysTick
void SysTick_Handler(void)
{
    sysTickUptime++;
}

// Return system uptime in microseconds (rollover in 1.5 days)
volatile uint64_t micros(void)
{
  return (sysTickUptime * 3125ul)/100ul;  // The convsersion is 31.25, so doing fixed-point math to be exact
}

// Return system uptime in milliseconds (rollover in 1.5 days)
volatile uint32_t millis(void)
{
    return (volatile uint32_t)(sysTickUptime >> 5);  // ( >> 5 is the same as divide by 32, but takes one operation)
}

void systemInit(void)
{
    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); //2 bit preemption, 2 bit sub priority

    // Configure Systick
    SysTick_Config(SystemCoreClock / 32000 + 28);
    NVIC_SetPriority(SysTick_IRQn, 0);

    //TODO: Should these be abstracted with the board-specific (ie revo_f4.h) file?
    RCC_AHB2PeriphClockCmd(RCC_AHB2Periph_OTG_FS, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI3, ENABLE);
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE);
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C2, ENABLE);

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM5, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM9, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM8, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM12, ENABLE);

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);
}

void delayMicroseconds(uint32_t us)
{
    uint32_t now = micros();
    volatile uint64_t m;
    while ((m=micros()) - now < us);
}

void delay(uint32_t ms)
{
    while (ms--)
        delayMicroseconds(1000);
}