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controller/Output/uartOut/arm/uart_serial.c

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/* Copyright (C) 2014 by Jacob Alexander
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "uart_serial.h"
#include <Lib/OutputLib.h>
#include <Lib/Interrupts.h>
#include <string.h> // For memcpy
// ----- Variables -----
#define uart0_buffer_size 128 // 128 byte buffer
volatile uint8_t uart0_buffer_head = 0;
volatile uint8_t uart0_buffer_tail = 0;
volatile uint8_t uart0_buffer_items = 0;
volatile uint8_t uart0_buffer[uart0_buffer_size];
volatile uint8_t uart_configured = 0;
// ----- Interrupt Functions -----
void uart0_status_isr()
{
cli(); // Disable Interrupts
// UART0_S1 must be read for the interrupt to be cleared
if ( UART0_S1 & ( UART_S1_RDRF | UART_S1_IDLE ) )
{
uint8_t available = UART0_RCFIFO;
// If there was actually nothing
if ( available == 0 )
{
// Cleanup
available = UART0_D;
UART0_CFIFO = UART_CFIFO_RXFLUSH;
sei();
return;
}
// Read UART0 into buffer until FIFO is empty
while ( available-- > 0 )
{
uart0_buffer[uart0_buffer_tail++] = UART0_D;
uart0_buffer_items++;
// Wrap-around of tail pointer
if ( uart0_buffer_tail >= uart0_buffer_size )
{
uart0_buffer_tail = 0;
}
// Make sure the head pointer also moves if circular buffer is overwritten
if ( uart0_buffer_head == uart0_buffer_tail )
{
uart0_buffer_head++;
}
// Wrap-around of head pointer
if ( uart0_buffer_head >= uart0_buffer_size )
{
uart0_buffer_head = 0;
}
}
}
sei(); // Re-enable Interrupts
}
// ----- Functions -----
void uart_serial_setup()
{
// Indication that the UART is not ready yet
uart_configured = 0;
// Setup the the UART interface for keyboard data input
SIM_SCGC4 |= SIM_SCGC4_UART0; // Disable clock gating
// MCHCK
#if defined(_mk20dx128vlf5_)
// Pin Setup for UART0
PORTA_PCR1 = PORT_PCR_PE | PORT_PCR_PS | PORT_PCR_PFE | PORT_PCR_MUX(2); // RX Pin
PORTA_PCR2 = PORT_PCR_DSE | PORT_PCR_SRE | PORT_PCR_MUX(2); // TX Pin
// Teensy
#else
// Pin Setup for UART0
PORTB_PCR16 = PORT_PCR_PE | PORT_PCR_PS | PORT_PCR_PFE | PORT_PCR_MUX(3); // RX Pin
PORTB_PCR17 = PORT_PCR_DSE | PORT_PCR_SRE | PORT_PCR_MUX(3); // TX Pin
#endif
// Setup baud rate - 115200 Baud
// 48 MHz / ( 16 * Baud ) = BDH/L
// Baud: 115200 -> 48 MHz / ( 16 * 115200 ) = 26.0416667
// Thus baud setting = 26
// NOTE: If finer baud adjustment is needed see UARTx_C4 -> BRFA in the datasheet
uint16_t baud = 26; // Max setting of 8191
UART0_BDH = (uint8_t)(baud >> 8);
UART0_BDL = (uint8_t)baud;
UART0_C4 = 0x02;
// 8 bit, No Parity, Idle Character bit after stop
UART0_C1 = UART_C1_ILT;
// Interrupt notification watermarks
UART0_TWFIFO = 2;
UART0_RWFIFO = 4;
// TX FIFO Disabled, TX FIFO Size 1 (Max 8 datawords), RX FIFO Enabled, RX FIFO Size 1 (Max 8 datawords)
// TX/RX FIFO Size:
// 0x0 - 1 dataword
// 0x1 - 4 dataword
// 0x2 - 8 dataword
UART0_PFIFO = UART_PFIFO_TXFE | UART_PFIFO_RXFE;
// Reciever Inversion Disabled, LSBF
// UART_S2_RXINV UART_S2_MSBF
UART0_S2 |= 0x00;
// Transmit Inversion Disabled
// UART_C3_TXINV
UART0_C3 |= 0x00;
// TX Enabled, RX Enabled, RX Interrupt Enabled, Generate idles
// UART_C2_TE UART_C2_RE UART_C2_RIE UART_C2_ILIE
UART0_C2 = UART_C2_TE | UART_C2_RE | UART_C2_RIE | UART_C2_ILIE;
// Add interrupt to the vector table
NVIC_ENABLE_IRQ( IRQ_UART0_STATUS );
// UART is now ready to use
uart_configured = 1;
}
// Get the next character, or -1 if nothing received
int uart_serial_getchar()
{
if ( !uart_configured )
return -1;
unsigned int value = -1;
// Check to see if the FIFO has characters
if ( uart0_buffer_items > 0 )
{
value = uart0_buffer[uart0_buffer_head++];
uart0_buffer_items--;
// Wrap-around of head pointer
if ( uart0_buffer_head >= uart0_buffer_size )
{
uart0_buffer_head = 0;
}
}
return value;
}
// Number of bytes available in the receive buffer
int uart_serial_available()
{
return uart0_buffer_items;
}
// Discard any buffered input
void uart_serial_flush_input()
{
uart0_buffer_head = 0;
uart0_buffer_tail = 0;
uart0_buffer_items = 0;
}
// Transmit a character. 0 returned on success, -1 on error
int uart_serial_putchar( uint8_t c )
{
if ( !uart_configured )
return -1;
while ( !( UART0_SFIFO & UART_SFIFO_TXEMPT ) ); // Wait till there is room to send
UART0_D = c;
return 0;
}
int uart_serial_write( const void *buffer, uint32_t size )
{
if ( !uart_configured )
return -1;
const uint8_t *data = (const uint8_t *)buffer;
uint32_t position = 0;
// While buffer is not empty and transmit buffer is
while ( position < size )
{
while ( !( UART0_SFIFO & UART_SFIFO_TXEMPT ) ); // Wait till there is room to send
UART0_D = data[position++];
}
return 0;
}
void uart_serial_flush_output()
{
// Delay until buffer has been sent
while ( !( UART0_SFIFO & UART_SFIFO_TXEMPT ) ); // Wait till there is room to send
}
void uart_device_reload()
{
asm volatile("bkpt");
}