/* | |
* FreeRTOS Kernel V10.1.1 | |
* Copyright (C) 2018 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; | |
} | |
} |