text: /******************************************************************************
   * Copyright 2020 The Firmament Authors. All Rights Reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   *****************************************************************************/
  
  #include "usart.h"
  #include "debug.h"
  #include <stdio.h>
  
  RING_BUFFER_Def rb;
  
  uint8_t send_ch(uint8_t ch)
  {
      USART_SendData(USART2, (uint8_t)ch);
  
      /* Loop until the end of transmission */
      while (USART_GetFlagStatus(USART2, USART_FLAG_TC) == RESET)
          ;
  
      return ch;
  }
  
  uint16_t send(uint8_t* data, uint16_t len)
  {
      uint16_t i;
  
      for (i = 0; i < len; i++) {
          send_ch(data[i]);
      }
  
      return len;
  }
  
  uint8_t read_ch(uint8_t* ch)
  {
      if (rb.head != rb.tail) {
          *ch = rb.buff[rb.tail];
          rb.tail = (rb.tail + 1) % RING_BUFFER_SIZE;
          return 1;
      }
  
      return 0;
  }
  
  uint8_t usart_config_baud_rate(USART_TypeDef* USARTx, uint32_t baud_rate)
  {
      USART_InitTypeDef USART_InitStructure;
  
      USART_InitStructure.USART_BaudRate = baud_rate;
      USART_InitStructure.USART_WordLength = USART_WordLength_8b;
      USART_InitStructure.USART_StopBits = USART_StopBits_1;
      USART_InitStructure.USART_Parity = USART_Parity_No;
      USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
      USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
      USART_Init(USARTx, &USART_InitStructure);
  
      USART_ITConfig(USARTx, USART_IT_RXNE, ENABLE);
  
      /* Enable USART */
      USART_Cmd(USARTx, ENABLE);
  }
  
  uint8_t usart_init(void)
  {
      GPIO_InitTypeDef GPIO_InitStructure;
      USART_InitTypeDef USART_InitStructure;
      NVIC_InitTypeDef NVIC_InitStructure;
  
      /*init ring budder*/
      rb.head = rb.tail = 0;
  
      /* Enable Clock */
      RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);
      RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
  
      /* Configure the NVIC Preemption Priority Bits */
      NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);
  
      /* Enable the USART2 Interrupt */
      NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
      NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
      NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
      NVIC_Init(&NVIC_InitStructure);
  
      /* Configure USART Tx as alternate function push-pull */
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
      GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
      GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
      GPIO_Init(GPIOA, &GPIO_InitStructure);
      /* Configure USART Rx as input floating */
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
      GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
      GPIO_Init(GPIOA, &GPIO_InitStructure);
  
      USART_InitStructure.USART_BaudRate = 230400;
      USART_InitStructure.USART_WordLength = USART_WordLength_8b;
      USART_InitStructure.USART_StopBits = USART_StopBits_1;
      USART_InitStructure.USART_Parity = USART_Parity_No;
      USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
      USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
      USART_Init(USART2, &USART_InitStructure);
  
      /* Enable USART2 Receive interrupts */
      USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);
  
      /* Enable USART */
      USART_Cmd(USART2, ENABLE);
  
      /* Config USART1 for debug */
      RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
  
      /* Configure USART Tx as alternate function push-pull */
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
      GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
      GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
      GPIO_Init(GPIOA, &GPIO_InitStructure);
      /* Configure USART Rx as input pull up, 
       * because input floating will result in unstable voltage level if sbus cable is not connected */
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
      GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
      GPIO_Init(GPIOA, &GPIO_InitStructure);
  
      USART_InitStructure.USART_BaudRate = 115200;
      USART_InitStructure.USART_WordLength = USART_WordLength_8b;
      USART_InitStructure.USART_StopBits = USART_StopBits_1;
      USART_InitStructure.USART_Parity = USART_Parity_No;
      USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
      USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
      USART_Init(USART1, &USART_InitStructure);
  
      /* Enable USART */
      USART_Cmd(USART1, ENABLE);
  
      return 1;
  }
  
  /**
    * @brief  Retargets the C library printf function to the USART.
    * @param  None
    * @retval None
    */
  int fputc(int ch, FILE* f)
  {
      /* Place your implementation of fputc here */
      /* e.g. write a character to the USART */
      USART_SendData(USART1, (uint8_t)ch);
  
      /* Loop until the end of transmission */
      while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET) { }
  
      return ch;
  }
  
  void console_putc(uint8_t ch)
  {
      /* Place your implementation of fputc here */
      /* e.g. write a character to the USART */
      USART_SendData(USART1, (uint8_t)ch);
  
      /* Loop until the end of transmission */
      while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET) { }
  }
  
  void USART2_irq_event_handler(void)
  {
      if (USART_GetITStatus(USART2, USART_IT_RXNE) != RESET) {
          rb.buff[rb.head] = USART_ReceiveData(USART2); /* this process will clear EXNE flag */
          rb.head = (rb.head + 1) % RING_BUFFER_SIZE;
  
          // if(rb.head == rb.tail)
          // 	debug("ring buffer is full\n");
      }
  }
  