wchTest_UART_int.ino

const size_t usart1_buff_size = 256;
char usart1_buff[usart1_buff_size];
uint16_t usart1_buff_write = 0;
uint16_t usart1_buff_read = 0;

#ifdef __cplusplus
extern "C" {
#endif
  void USART1_IRQHandler(void) __attribute__((interrupt("WCH-Interrupt-fast")));
  void USART1_IRQHandler(void) {
    USART_ClearITPendingBit(USART1, USART_IT_RXNE);
    usart1_buff[usart1_buff_write] = USART_ReceiveData(USART1);
    usart1_buff_write++;
    usart1_buff_write %= usart1_buff_size;
  }
#ifdef __cplusplus
}
#endif

int usart1_available() {
  return (usart1_buff_write != usart1_buff_read);
}

char usart1_get() {
  uint8_t c;
  if (usart1_buff_write != usart1_buff_read) {
    c = usart1_buff[usart1_buff_read];
    usart1_buff_read++;
    usart1_buff_read %= usart1_buff_size;
    return c;
  }
  return 0;
}


void setup() {
  Serial.begin(115200);
  USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);
  NVIC_SetPriority(USART1_IRQn, UART_IRQ_PRIO);
  NVIC_EnableIRQ(USART1_IRQn);
}

void loop() {
  while (usart1_available()) {
    Serial.print(usart1_get());
  }

  delay(1000);
}