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RIOT/cpu/cc26x0/periph/uart.c 3.09 KB
a752c7ab   elopes   add first test an...
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  /*
   * Copyright (C) 2016 Leon George
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @ingroup     cpu_cc26x0
   * @ingroup     drivers_periph_uart
   * @{
   *
   * @file
   * @brief       Low-level UART driver implementation
   *
   * @author      Leon M. George <leon@georgemail.eu>
   *
   * @}
   */
  
  #include "cpu.h"
  #include "periph/uart.h"
  
  /**
   * @brief   Bit mask for the fractional part of the baudrate
   */
  #define FRAC_BITS           (6U)
  #define FRAC_MASK           (0x3f)
  
  /**
   * @brief   Get the enable mask depending on enabled HW flow control
   */
  #if UART_HW_FLOW_CONTROL
  #define ENABLE_MASK         (UART_CTSEN | UART_CTL_RTSEN | \
                               UART_CTL_RXE | UART_CTL_TXE | UART_CTL_UARTEN)
  #else
  #define ENABLE_MASK         (UART_CTL_RXE | UART_CTL_TXE | UART_CTL_UARTEN)
  #endif
  
  /**
   * @brief allocate memory to store callback functions
   */
  static uart_isr_ctx_t ctx[UART_NUMOF];
  
  
  int uart_init(uart_t uart, uint32_t baudrate, uart_rx_cb_t rx_cb, void *arg)
  {
      /* make sure the uart device is valid */
      if (uart != 0) {
          return UART_NODEV;
      }
  
      /* enable clocks: serial power domain and UART */
      PRCM->PDCTL0SERIAL = 1;
      while (!(PRCM->PDSTAT0 & PDSTAT0_SERIAL_ON)) ;
      uart_poweron(uart);
  
      /* disable and reset the UART */
      UART->CTL = 0;
  
      /* save context */
      ctx[0].rx_cb = rx_cb;
      ctx[0].arg = arg;
  
      /* configure pins */
      IOC->CFG[UART_TX_PIN] =  IOCFG_PORTID_UART0_TX;
      IOC->CFG[UART_RX_PIN] = (IOCFG_PORTID_UART0_RX | IOCFG_INPUT_ENABLE);
  #if UART_HW_FLOW_CONTROL
      IOC->CFG[UART_RTS_PIN] =  IOCFG_PORTID_UART0_RTS;
      IOC->CFG[UART_CTS_PIN] = (IOCFG_PORTID_UART0_CTS | IOCFG_INPUT_ENABLE);
  #endif
  
      /* calculate baud-rate */
      uint32_t tmp = (CLOCK_CORECLOCK * 4);
      tmp += (baudrate / 2);
      tmp /= baudrate;
      UART->IBRD = (tmp >> FRAC_BITS);
      UART->FBRD = (tmp & FRAC_MASK);
  
      /* configure line to 8N1 mode, LRCH must be written after IBRD and FBRD! */
      UART->LCRH = UART_LCRH_WLEN_8;
  
      /* enable the RX interrupt */
      UART->IMSC = UART_IMSC_RXIM;
      NVIC_EnableIRQ(UART0_IRQN);
  
      /* start the UART */
      UART->CTL = ENABLE_MASK;
  
      return UART_OK;
  }
  
  void uart_write(uart_t uart, const uint8_t *data, size_t len)
  {
      for (size_t i = 0; i < len; i++) {
          while (UART->FR & UART_FR_TXFF) {}
          UART->DR = data[i];
      }
  }
  
  void uart_poweron(uart_t uart)
  {
      PRCM->UARTCLKGR = 1;
      PRCM->CLKLOADCTL = CLKLOADCTL_LOAD;
      while (!(PRCM->CLKLOADCTL & CLKLOADCTL_LOADDONE)) {}
  
      UART->CTL = ENABLE_MASK;
  }
  
  void uart_poweroff(uart_t uart)
  {
      UART->CTL = 0;
  
      PRCM->UARTCLKGR = 0;
      PRCM->CLKLOADCTL = CLKLOADCTL_LOAD;
      while (!(PRCM->CLKLOADCTL & CLKLOADCTL_LOADDONE)) {}
  
  }
  
  void isr_uart(void)
  {
      /* remember pending interrupts */
      uint32_t mis = UART->MIS;
      /* clear them */
      UART->ICR = mis;
  
      /* read received byte and pass it to the RX callback */
      if (mis & UART_MIS_RXMIS) {
          ctx[0].rx_cb(ctx[0].arg, (uint8_t)UART->DR);
      }
  
      cortexm_isr_end();
  }