// Hello World - Echo Test von S.F. webseite, aber mit dem neuen usb_vcp
// https://www.mikrocontroller.net/topic/513315?goto=6623438#6623438

#include <stdio.h>
#include "stm32f0xx.h"
#include "usb_vcp.h"


// Delay some milliseconds
void delay_ms(int ms)
{
    //[ALEX] uint32_t start=systick_count;
    uint32_t start=HAL_GetTick();
    while (HAL_GetTick()-start<ms);

}

// Called by Assembler startup code
void SystemInit(void)
{
	// Enable the Internal High Speed oscillator (HSI48)
   		SET_BIT(RCC->CR2, RCC_CR2_HSI48ON);
   		while (!READ_BIT(RCC->CR2, RCC_CR2_HSI48RDY));

 	// switch SYSCLK to HSI48
   		MODIFY_REG(RCC->CFGR, RCC_CFGR_SW, RCC_CFGR_SW_HSI48);
   		while (!READ_BIT(RCC->CFGR, RCC_CFGR_SWS_HSI48));

   		SystemCoreClock = 48000000;


   	//  Configure the USB clock source
   		MODIFY_REG(RCC->CFGR3, RCC_CFGR3_USBSW, RCC_CFGR3_USBSW_HSI48);

    // testhalber die clk langsamer machen
   	//  SystemCoreClock = 24000000;
	//	MODIFY_REG(RCC->CFGR, RCC_CFGR_HPRE, RCC_CFGR_HPRE_DIV2); // clock teilen

	// Initialize system timer
   		SysTick_Config(SystemCoreClock/1000);

	// Peripheral: Enable SYSCFG CLK
   		SET_BIT(RCC->APB2ENR, RCC_APB2ENR_SYSCFGEN);
   		while (!READ_BIT(RCC->APB2ENR, RCC_APB2ENR_SYSCFGEN));

	// Peripheral: Enable Power Interface Clock
   		SET_BIT(RCC->APB1ENR, RCC_APB1ENR_PWREN);
   		while (!READ_BIT(RCC->APB1ENR, RCC_APB1ENR_PWREN));

	// remap pins for USB
   		SYSCFG->CFGR1 |= (SYSCFG_CFGR1_PA11_PA12_RMP);

	// Setup Clock Recovery System CRS to sync with USB SOF
   		// enable CRS
   		SET_BIT(RCC->APB1ENR, RCC_APB1ENR_CRSEN);
   		while (!READ_BIT(RCC->APB1ENR, RCC_APB1ENR_CRSEN));

   		// reset CRS
   		RCC->APB1RSTR |= (RCC_APB1RSTR_CRSRST);
   		RCC->APB1RSTR &= ~(RCC_APB1RSTR_CRSRST);

   		CRS->CFGR =  0 | 							// prescaler: no divider
    			CRS_CFGR_SYNCSRC_1 |  				// source: USB SOF
 				CRS_CFGR_SYNCPOL   |  				// polarity: falling
 				(47999U << CRS_CFGR_RELOAD_Pos) | 	// reload value
 				(34 << CRS_CFGR_FELIM_Pos); 		// error limit value
    			// reload value =  f_{target} / f_{sync} - 1
    			// reload value =  48e6/1e3 - 1 = 47999
    			// error limit value: from cubeMx code generator

   		// Adjust HSI48 oscillator smooth trimming
   		MODIFY_REG(CRS->CR, CRS_CR_TRIM, (32 << CRS_CR_TRIM_Pos));
    			// trim value: from cubeMx code genererator

   		// START AUTOMATIC SYNCHRONIZATION
   		SET_BIT(CRS->CR, CRS_CR_AUTOTRIMEN | CRS_CR_CEN);    	  // enable automatic trimming & frequency error counter


/*
   	// Use TIM14 to generate the reference CLK: 614kHz Signal to PB1
   	   	// enable TIM14
   	   	SET_BIT(RCC->APB1ENR, RCC_APB1ENR_TIM14EN);
   	   	while (!READ_BIT(RCC->APB1ENR, RCC_APB1ENR_TIM14EN));

   	   	// reset TIM14
   	   	RCC->APB1RSTR |= (RCC_APB1RSTR_TIM14RST);
   	   	RCC->APB1RSTR &= ~(RCC_APB1RSTR_TIM14RST);

   	   	// divide 48MHz by 78 = 615.4kHz
   	   	TIM14->ARR = 77;	// period: 78 cycles
   	   	TIM14->CCR1 = 39;	// 50% duty cycle
   		TIM14->CCMR1 = 0; // reset value
   	   	MODIFY_REG(TIM14->CCMR1, TIM_CCMR1_OC1M, (0b110 << TIM_CCMR1_OC1M_Pos));    // PWM MODE 1 (mode 2 is just inverted)
   	   	//SET_BIT(TIM14->CCMR1, TIM_CCMR1_OC1PE);				// preload enable
   	   	// wird nie geändert

   	   	// enable Cap-Comp CH1
   	   	SET_BIT(TIM14->CCER, TIM_CCER_CC1E);

   	   	TIM14->CR1 = 0;	// reset value
   	   	//SET_BIT(TIM14->CR1, TIM_CR1_ARPE | TIM_CR1_CEN);	// auto reload & counter enable
   	   	SET_BIT(TIM14->CR1,  TIM_CR1_CEN);	//  counter enable

   	   	// ensure TIM14CH1 -> PB1 is set to AF0 !
*/

}

void init_io()
{
    // Enable USB
    SET_BIT(RCC->APB1ENR, RCC_APB1ENR_USBEN);

	// enable GPIOB CLK
	SET_BIT(RCC->AHBENR, RCC_AHBENR_GPIOBEN);
	while (!READ_BIT(RCC->AHBENR, RCC_AHBENR_GPIOBEN));
/*
	// einfach rüberkopiert -> PWM-Ausgang auf PB1
	GPIO_InitTypeDef GPIO_InitStruct = {0};
	//Configure GPIO pin : PB1
	GPIO_InitStruct.Pin = GPIO_PIN_1;
	GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;	// alternate functino: TIM14
	GPIO_InitStruct.Pull = GPIO_NOPULL;
	HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
*/
}

// Alternative: Redirect standard output to the USB port, e.g. from puts() or printf()
int _write(int file, char *ptr, int len)
{
    for (int i=0; i<len; i++)
    {
        UsbCharOut(*ptr++);
    }
    return len;
}

int main(void)
{
	// remap pins for USB
	SYSCFG->CFGR1 |= (SYSCFG_CFGR1_PA11_PA12_RMP);

    init_io();
    UsbSetup();

    SET_BIT(USB->BCDR, USB_BCDR_DPPU);				// enable pullup USB

    while (1)
    {
        delay_ms(100);

        UsbStrOut("Hello World!\n");

        // Send echo of received characters back
        while (UsbRxAvail())
        {
            char c=UsbGetChar();
            UsbCharOut(c);
        }

        delay_ms(900);

    }

}