/** ---------------------------------------------------------------------------
 * @brief dlms_comms::Tx_interrupt
 */
void dlms_comms::Tx_interrupt(void)
{
    // enable the receiver, we are finito with the transmission of characters
    // this changes the direction on the transceiver buffer on the rRS485 buffer
    dir_485 = 0;       
    // disable the transmit empty interrupt, to prevent it just to happen again when we exit
    rs485.attach(NULL, Serial::TxIrq);
}

    // due to a bug in mbed , the debug display printf disable the second uart receive interrupts  
    // this will enable the interrupts on a regular basis

    // when characters received, run the Rx_interrupt method
    rs485.attach(this,
                 &dlms_comms::Rx_interrupt,
                 Serial::RxIrq); 

/** ---------------------------------------------------------------------------
 * @brief dlms_comms::send_packet This method sends a serial packet data to the
 * rs485 bus, the directoion of the tranceiver chip is changed to transmit and
 * the packet is tranmitted.
 * @param ptr     Pointer address for start of the packet
 * @param length  Packet length
 * @note          The direction is changed with a interrupt when the transmitter
 *                is empty
 */
void dlms_comms::send_packet (const UINT_8  *ptr,
                              const UINT_8   length)
{
    // local stack variable
    UINT_8 * tmp_ptr =(UINT_8 *) ptr;

    // change the tranceiver direction to output
    dir_485 = 1;
    for (UINT_8 i= 0; i < length; i++)
    {
        rs485.putc (*tmp_ptr++);
    }
    rs485.attach(this,
                 &dlms_comms::Tx_interrupt,
                 Serial::TxIrq);
}

/** ---------------------------------------------------------------------------
 * @brief dlms_comms::Rx_interrupt . This method received all characters from
 * the uart and saved it in a ring buffer, 256 bytes long. The CPU only has 16
 * byte fifo, this makes it a 256 bit fifo
 */
void dlms_comms::Rx_interrupt(void)
{
    UINT_8 value;
    rx_irq_count++;
    // read the uart and place character in ring buffer
    value = rs485.getc();
    rx_buffer[rx_head_ptr++] = value;
}
/** ---------------------------------------------------------------------------
 * @brief dlms_comms::available This method return if we have any characters
 * available (received on the rs485 port)
 * @return true if characters received on the rs485
 */
bool dlms_comms::char_available (void)
{
    if (rx_head_ptr == rx_tail_ptr)
        // nope
        return false;
    else
        return true;
}
/** ---------------------------------------------------------------------------
 * @brief dlms_comms::get_char This method return the last character received
 * on the rs485 port
 * @return Unsigned byte
 * @note The user must make sure that characters are available before, else
 * this method shall wait for the next character, no timeouts yet
 */
UINT_8 dlms_comms::get_char (void)
{
    // we have to wait for at least on charcter in the ring buffer
    while (char_available() == false);
    // return the character
    return (rx_buffer[rx_tail_ptr++]);
}