FreeRTOS-Kernel/FreeRTOS/Demo/AVR_Dx_Atmel_Studio/RTOSDemo/serial/serial.c

/*
 * FreeRTOS Kernel V10.3.1
 * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
 *
 * 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
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 * 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
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 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * http://www.FreeRTOS.org
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 */


/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR IAR AVR PORT. */

#include <stdlib.h>
#include "FreeRTOS.h"
#include "queue.h"
#include "task.h"
#include "serial.h"
#include <avr/interrupt.h>

#define USART_BAUD_RATE(BAUD_RATE) ((float)(configCPU_CLOCK_HZ * 64 / (16 * (float)BAUD_RATE)) + 0.5)
 
static QueueHandle_t xRxedChars;
static QueueHandle_t xCharsForTx;

#define vInterruptOn() USART1.CTRLA |= (1 << USART_DREIE_bp)										

#define vInterruptOff()	USART1.CTRLA &= ~(1 << USART_DREIE_bp)

xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
	portENTER_CRITICAL();
	{
		/* Create the queues used by the com test task. */
		xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
		xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );

		USART1.BAUD = (uint16_t)USART_BAUD_RATE(ulWantedBaud); /* set baud rate register */

		USART1.CTRLA = 0 << USART_ABEIE_bp    /* Auto-baud Error Interrupt Enable: disabled */
						| 0 << USART_DREIE_bp  /* Data Register Empty Interrupt Enable: disabled */
						| 1 << USART_LBME_bp   /* Loop-back Mode Enable: enabled */
						| USART_RS485_OFF_gc   /* RS485 Mode disabled */
						| 1 << USART_RXCIE_bp  /* Receive Complete Interrupt Enable: enabled */
						| 0 << USART_RXSIE_bp  /* Receiver Start Frame Interrupt Enable: disabled */
						| 0 << USART_TXCIE_bp; /* Transmit Complete Interrupt Enable: disabled */

		USART1.CTRLB = 0 << USART_MPCM_bp       /* Multi-processor Communication Mode: disabled */
						| 0 << USART_ODME_bp     /* Open Drain Mode Enable: disabled */
						| 1 << USART_RXEN_bp     /* Reciever enable: enabled */
						| USART_RXMODE_NORMAL_gc /* Normal mode */
						| 0 << USART_SFDEN_bp    /* Start Frame Detection Enable */
						| 1 << USART_TXEN_bp;    /* Transmitter Enable: enabled */
		
	}
	
	portEXIT_CRITICAL();
	
	/* Unlike other ports, this serial code does not allow for more than one
	com port.  We therefore don't return a pointer to a port structure and can
	instead just return NULL. */
	return NULL;
}
/*-----------------------------------------------------------*/

signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t xBlockTime )
{
	/* Get the next character from the buffer.  Return false if no characters
	are available, or arrive before xBlockTime expires. */
	if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
	{
		return pdTRUE;
	}
	else
	{
		return pdFALSE;
	}
}
/*-----------------------------------------------------------*/

signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, TickType_t xBlockTime )
{
	/* Return false if after the block time there is no room on the Tx queue. */
	if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
	{
		return pdFAIL;
	}
	
	vInterruptOn();
	
	return pdPASS;
}
/*-----------------------------------------------------------*/

void vSerialClose( xComPortHandle xPort )
{
unsigned char ucByte;

	/* Turn off the interrupts.  We may also want to delete the queues and/or
	re-install the original ISR. */

	portENTER_CRITICAL();
	{
		vInterruptOff();
		
		ucByte = USART1.CTRLB ;									
		ucByte &= (0xFF ^(1 << USART_RXEN_bp));					
		USART1.CTRLB = ucByte ;	
		
	}
	portEXIT_CRITICAL();
}
/*-----------------------------------------------------------*/

ISR(USART1_RXC_vect)
{
signed char ucChar, xHigherPriorityTaskWoken = pdFALSE;

	/* Get the character and post it on the queue of Rxed characters.
	If the post causes a task to wake force a context switch as the woken task
	may have a higher priority than the task we have interrupted. */
	ucChar = USART1.RXDATAL;

	xQueueSendFromISR( xRxedChars, &ucChar, &xHigherPriorityTaskWoken );

	if( xHigherPriorityTaskWoken != pdFALSE )
	{
		portYIELD_FROM_ISR();
	}
		
}

ISR(USART1_DRE_vect)
{
signed char cChar, cTaskWoken = pdFALSE;

	if( xQueueReceiveFromISR( xCharsForTx, &cChar, &cTaskWoken ) == pdTRUE )
	{
		/* Send the next character queued for Tx. */
		USART1.TXDATAL = cChar;
	}
	else
	{
		/* Queue empty, nothing to send. */
		vInterruptOff();
	}
}