crashtest-r0ket/firmware/core/uart/uart.c

/**************************************************************************/
/*! 
    @file     uart.c
    @author   K. Townsend (microBuilder.eu)
    @date     22 March 2010
    @version  0.10

    @section DESCRIPTION

    Generic code for UART-based communication.  Incoming text is stored
    in a FIFO Queue for safer processing.

    @section Example: Sending text via UART

    @code 
    #include "core/cpu/cpu.h"
    #include "core/uart/uart.h"
    ...
    #define UARTBUFFERSIZE 5
    ...
    cpuInit();
    uartInit(57600);
    ...
    uint8_t uartBuffer[UARTBUFFERSIZE] = { 'T', 'e', 's', 't', '\n' };
  
    // Send contents of uartBuffer
    uartSend((uint8_t *)uartBuffer, UARTBUFFERSIZE);
    @endcode

    @section Example: Reading from UART

    @code

    #include "core/cpu/cpu.h"
    #include "core/uart/uart.h"

    cpuInit();
    uartInit(57600);

    // Get a reference to the UART control block
    uart_pcb_t *pcb = uartGetPCB();

    // Read any text available in the queue
    while (uartRxBufferDataPending())
    {
      // Read the first available character
      uint8_t c = uartRxBufferRead();

      // read out the data in the buffer and echo it back to the host. 
      switch (c)
      {
        case '\r':
            printf("\n\r");
            break;        
        default:
            printf("%c", c);
            break;
      }
    }

    #endcode
	
    @section LICENSE

    Software License Agreement (BSD License)

    Copyright (c) 2010, microBuilder SARL
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are met:
    1. Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.
    2. Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions and the following disclaimer in the
    documentation and/or other materials provided with the distribution.
    3. Neither the name of the copyright holders nor the
    names of its contributors may be used to endorse or promote products
    derived from this software without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
    EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
    DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
    (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
    ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**************************************************************************/

#include <string.h>

#include "uart.h"

#ifdef CFG_INTERFACE_UART
  #include "core/cmd/cmd.h"
#endif

/**************************************************************************/
/*!
    UART protocol control block, which is used to safely access the
    RX FIFO buffer from elsewhere in the code.  This should be accessed
    through 'uartGetPCB()'.
*/
/**************************************************************************/
static uart_pcb_t pcb;

/**************************************************************************/
/*!
    IRQ to handle incoming data, etc.
*/
/**************************************************************************/
void UART_IRQHandler(void)
{
  uint8_t IIRValue, LSRValue;
  uint8_t Dummy = Dummy;

  IIRValue = UART_U0IIR;
  IIRValue &= ~(UART_U0IIR_IntStatus_MASK); /* skip pending bit in IIR */
  IIRValue &= UART_U0IIR_IntId_MASK;        /* check bit 1~3, interrupt identification */

  // 1.) Check receiver line status
  if (IIRValue == UART_U0IIR_IntId_RLS)
  {
    LSRValue = UART_U0LSR;
    // Check for errors
    if (LSRValue & (UART_U0LSR_OE | UART_U0LSR_PE | UART_U0LSR_FE | UART_U0LSR_RXFE | UART_U0LSR_BI))
    {
      /* There are errors or break interrupt */
      /* Read LSR will clear the interrupt */
      pcb.status = LSRValue;
      Dummy = UART_U0RBR;	/* Dummy read on RX to clear interrupt, then bail out */
      return;
    }
    // No error and receive data is ready
    if (LSRValue & UART_U0LSR_RDR_DATA)
    {
      /* If no error on RLS, normal ready, save into the data buffer. */
      /* Note: read RBR will clear the interrupt */
      uartRxBufferWrite(UART_U0RBR);
    }
  }

  // 2.) Check receive data available
  else if (IIRValue == UART_U0IIR_IntId_RDA)
  {
    // Add incoming text to UART buffer
    uartRxBufferWrite(UART_U0RBR);
  }

  // 3.) Check character timeout indicator
  else if (IIRValue == UART_U0IIR_IntId_CTI)
  {
    /* Bit 9 as the CTI error */
    pcb.status |= 0x100;
  }

  // 4.) Check THRE (transmit holding register empty)
  else if (IIRValue == UART_U0IIR_IntId_THRE)
  {
    /* Check status in the LSR to see if valid data in U0THR or not */
    LSRValue = UART_U0LSR;
    if (LSRValue & UART_U0LSR_THRE)
    {
      pcb.pending_tx_data = 0;
    }
    else
    {
      pcb.pending_tx_data= 1;
    }
  }
  return;
}

/**************************************************************************/
/*!
    @brief  Get a pointer to the UART's protocol control block, which can
            be used to control the RX FIFO buffer and check whether UART
            has already been initialised or not.

    @section Example

    @code 
    // Make sure that UART is initialised
    uart_pcb_t *pcb = uartGetPCB();
    if (!pcb->initialised)
    {
      uartInit(CFG_UART_BAUDRATE);
    }
    @endcode

*/
/**************************************************************************/
uart_pcb_t *uartGetPCB()
{
    return &pcb;
}

/**************************************************************************/
/*! 
    @brief Initialises UART at the specified baud rate.

    @param[in]  baudRate
                The baud rate to use when configuring the UART.
*/
/**************************************************************************/
void uartInit(uint32_t baudrate)
{
  uint32_t fDiv;
  uint32_t regVal;

  NVIC_DisableIRQ(UART_IRQn);

  // Clear protocol control blocks
  memset(&pcb, 0, sizeof(uart_pcb_t));
  pcb.pending_tx_data = 0;
  uartRxBufferInit();

  /* Set 1.6 UART RXD */
  IOCON_PIO1_6 &= ~IOCON_PIO1_6_FUNC_MASK;
  IOCON_PIO1_6 |= IOCON_PIO1_6_FUNC_UART_RXD;

  /* Set 1.7 UART TXD */
  IOCON_PIO1_7 &= ~IOCON_PIO1_7_FUNC_MASK;	
  IOCON_PIO1_7 |= IOCON_PIO1_7_FUNC_UART_TXD;

  /* Enable UART clock */
  SCB_SYSAHBCLKCTRL |= (SCB_SYSAHBCLKCTRL_UART);
  SCB_UARTCLKDIV = SCB_UARTCLKDIV_DIV1;     /* divided by 1 */

  /* 8 bits, no Parity, 1 Stop bit */
  UART_U0LCR = (UART_U0LCR_Word_Length_Select_8Chars |
                UART_U0LCR_Stop_Bit_Select_1Bits |
                UART_U0LCR_Parity_Disabled |
                UART_U0LCR_Parity_Select_OddParity |
                UART_U0LCR_Break_Control_Disabled |
                UART_U0LCR_Divisor_Latch_Access_Enabled);

  /* Baud rate */
  regVal = SCB_UARTCLKDIV;
  fDiv = (((CFG_CPU_CCLK * SCB_SYSAHBCLKDIV)/regVal)/16)/baudrate;

  UART_U0DLM = fDiv / 256;
  UART_U0DLL = fDiv % 256;
  
  /* Set DLAB back to 0 */
  UART_U0LCR = (UART_U0LCR_Word_Length_Select_8Chars |
                UART_U0LCR_Stop_Bit_Select_1Bits |
                UART_U0LCR_Parity_Disabled |
                UART_U0LCR_Parity_Select_OddParity |
                UART_U0LCR_Break_Control_Disabled |
                UART_U0LCR_Divisor_Latch_Access_Disabled);
  
  /* Enable and reset TX and RX FIFO. */
  UART_U0FCR = (UART_U0FCR_FIFO_Enabled | 
                UART_U0FCR_Rx_FIFO_Reset | 
                UART_U0FCR_Tx_FIFO_Reset); 

  /* Read to clear the line status. */
  regVal = UART_U0LSR;

  /* Ensure a clean start, no data in either TX or RX FIFO. */
  while (( UART_U0LSR & (UART_U0LSR_THRE|UART_U0LSR_TEMT)) != (UART_U0LSR_THRE|UART_U0LSR_TEMT) );
  while ( UART_U0LSR & UART_U0LSR_RDR_DATA )
  {
    /* Dump data from RX FIFO */
    regVal = UART_U0RBR;
  }

  /* Set the initialised flag in the protocol control block */
  pcb.initialised = 1;
  pcb.baudrate = baudrate;

  /* Enable the UART Interrupt */
  NVIC_EnableIRQ(UART_IRQn);
  UART_U0IER = UART_U0IER_RBR_Interrupt_Enabled | UART_U0IER_RLS_Interrupt_Enabled;

  return;
}

/**************************************************************************/
/*! 
    @brief Sends the contents of supplied text buffer over UART.

    @param[in]  bufferPtr
                Pointer to the text buffer
    @param[in]  bufferPtr
                The size of the text buffer

    @section Example

    @code 
    // Set 5-character text buffer
    uint8_t uartBuffer[5] = { 'T', 'e', 's', 't', '\n' };
    // Send contents of uartBuffer
    uartSend((uint8_t *)uartBuffer, 5);
    @endcode

*/
/**************************************************************************/
void uartSend (uint8_t *bufferPtr, uint32_t length)
{
  while (length != 0)
  {
    /* THRE status, contain valid data */
    while ( !(UART_U0LSR & UART_U0LSR_THRE) );
    UART_U0THR = *bufferPtr;

    bufferPtr++;
    length--;
  }

  return;
}

/**************************************************************************/
/*! 
    @brief Sends a single byte over UART.

    @param[in]  byte
                Byte value to send

    @section Example

    @code 
    // Send 0xFF over UART
    uartSendByte(0xFF);
    // Send 'B' over UART (note single quotes)
    uartSendByte('B');
    @endcode

*/
/**************************************************************************/
void uartSendByte (uint8_t byte)
{
  /* THRE status, contain valid data */
  while ( !(UART_U0LSR & UART_U0LSR_THRE) );
  UART_U0THR = byte;

  return;
}