#include "lidar.h"

void lidar_init()
{
	RCC->AHB2ENR |= RCC_AHB2ENR_GPIOBEN;
	
	// port 11 alt func mode
	GPIOB->MODER &= ~(3 << (11 * 2));
	GPIOB->MODER |= 2 << (11 * 2);
	
	// set AF7 on AFRegister for GPIOB11
	GPIOB->AFR[1] &= ~(0xF << 12);
	GPIOB->AFR[1] |= 7 << 12;
	
	// very high speed
	GPIOB->OSPEEDR |= 3 << (11 * 2);
	
	// pull-up
	GPIOB->PUPDR &= ~(3 << (11 * 2));
	GPIOB->PUPDR |= 1 << (11 * 2);
	
	// SYSCLK selected as USART3 clock
	RCC->CCIPR &= ~(RCC_CCIPR_USART3SEL);
	RCC->CCIPR |= 1 << RCC_CCIPR_USART3SEL_Pos;
	RCC->APB1ENR1 |= RCC_APB1ENR1_USART3EN;
	
	USART3->CR1 = 0;
	USART3->CR2 = 0;
	USART3->CR3 = 0;
	
	USART3->BRR = 16000000UL / 115200UL;
	
	// parity control disable
	USART3->CR1 &= ~(USART_CR1_PCE);
	
	// word length 8 bit
	USART3->CR1 &= ~USART_CR1_M1 & ~USART_CR1_M0;
	
	// 1 stop bit
	USART3->CR2 &= ~USART_CR2_STOP;
	
	// receiver enable
	// interrupt generated whenever ORE = 1 or RXNE = 1
	USART3->CR1 |= USART_CR1_RE | USART_CR1_RXNEIE;
	
	// overrun disable
	USART3->CR3 |= USART_CR3_OVRDIS;
	
	// USART3 enable
	USART3->CR1 |= USART_CR1_UE;
	
	// Interrupt enable
	NVIC_EnableIRQ(USART3_IRQn);
}