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/*
* FreeRTOS Kernel V10.3.0
* 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
* 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.
*
* http://www.FreeRTOS.org
* http://aws.amazon.com/freertos
*
* 1 tab == 4 spaces!
*/
/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER.
*
* This file only supports UART 0
*/
/* Standard includes. */
#include <stdlib.h>
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "queue.h"
#include "task.h"
/* Demo application includes. */
#include "serial.h"
/* The queue used to hold received characters. */
static QueueHandle_t xRxedChars;
/* The queue used to hold characters waiting transmission. */
static QueueHandle_t xCharsForTx;
static volatile short sTHREEmpty;
static volatile short queueFail = pdFALSE;
/*-----------------------------------------------------------*/
xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
/* Initialise the hardware. */
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) );
if( xRxedChars == 0 )
{
queueFail = pdTRUE;
}
if( xCharsForTx == 0 )
{
queueFail = pdTRUE;
}
/* Initialize UART asynchronous mode */
BGR0 = configCLKP1_CLOCK_HZ / ulWantedBaud;
SCR0 = 0x17; /* 8N1 */
SMR0 = 0x0d; /* enable SOT3, Reset, normal mode */
SSR0 = 0x02; /* LSB first, enable receive interrupts */
PIER08_IE2 = 1; /* enable input */
DDR08_D2 = 0; /* switch P08_2 to input */
DDR08_D3 = 1; /* switch P08_3 to output */
}
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 )
{
signed portBASE_TYPE xReturn;
/* Transmit a character. */
portENTER_CRITICAL();
{
if( sTHREEmpty == pdTRUE )
{
/* If sTHREEmpty is true then the UART Tx ISR has indicated that
there are no characters queued to be transmitted - so we can
write the character directly to the shift Tx register. */
sTHREEmpty = pdFALSE;
TDR0 = cOutChar;
xReturn = pdPASS;
}
else
{
/* sTHREEmpty is false, so there are still characters waiting to be
transmitted. We have to queue this character so it gets
transmitted in turn. */
/* Return false if after the block time there is no room on the Tx
queue. It is ok to block inside a critical section as each task
maintains it's own critical section status. */
if( xQueueSend(xCharsForTx, &cOutChar, xBlockTime) == pdTRUE )
{
xReturn = pdPASS;
}
else
{
xReturn = pdFAIL;
}
}
if( pdPASS == xReturn )
{
/* Turn on the Tx interrupt so the ISR will remove the character from the
queue and send it. This does not need to be in a critical section as
if the interrupt has already removed the character the next interrupt
will simply turn off the Tx interrupt again. */
SSR0_TIE = 1;
}
}
portEXIT_CRITICAL();
return pdPASS;
}
/*-----------------------------------------------------------*/
/*
* UART RX interrupt service routine.
*/
__interrupt void UART0_RxISR( void )
{
volatile signed char cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
/* Get the character from the UART and post it on the queue of Rxed
characters. */
cChar = RDR0;
xQueueSendFromISR( xRxedChars, ( const void *const ) &cChar, &xHigherPriorityTaskWoken );
if( xHigherPriorityTaskWoken )
{
/*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. */
portYIELD_FROM_ISR();
}
}
/*-----------------------------------------------------------*/
/*
* UART Tx interrupt service routine.
*/
__interrupt void UART0_TxISR( void )
{
signed char cChar;
signed portBASE_TYPE xTaskWoken = pdFALSE;
/* The previous character has been transmitted. See if there are any
further characters waiting transmission. */
if( xQueueReceiveFromISR(xCharsForTx, &cChar, &xTaskWoken) == pdTRUE )
{
/* There was another character queued - transmit it now. */
TDR0 = cChar;
}
else
{
/* There were no other characters to transmit. */
sTHREEmpty = pdTRUE;
/* Disable transmit interrupts */
SSR0_TIE = 0;
}
}
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