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/*
* FreeRTOS Kernel V10.4.0
* 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!
*/
/*
Changes from V3.0.0
+ ISRcode removed. Is now pulled inline to reduce stack-usage.
Changes from V3.0.1
*/
/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER. */
/* Scheduler header files. */
#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"
#include "serial.h"
/* Hardware pin definitions. */
#define serTX_PIN bTRC6
#define serRX_PIN bTRC7
/* Bit/register definitions. */
#define serINPUT ( 1 )
#define serOUTPUT ( 0 )
#define serINTERRUPT_ENABLED ( 1 )
/* All ISR's use the PIC18 low priority interrupt. */
#define serLOW_PRIORITY ( 0 )
/*-----------------------------------------------------------*/
/* Queues to interface between comms API and interrupt routines. */
QueueHandle_t xRxedChars;
QueueHandle_t xCharsForTx;
portBASE_TYPE xHigherPriorityTaskWoken;
/*-----------------------------------------------------------*/
xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned char ucQueueLength )
{
unsigned short usSPBRG;
/* Create the queues used by the ISR's to interface to tasks. */
xRxedChars = xQueueCreate( ucQueueLength, ( unsigned portBASE_TYPE ) sizeof( char ) );
xCharsForTx = xQueueCreate( ucQueueLength, ( unsigned portBASE_TYPE ) sizeof( char ) );
portENTER_CRITICAL();
/* Setup the IO pins to enable the USART IO. */
serTX_PIN = serINPUT; // YES really! See datasheet
serRX_PIN = serINPUT;
/* Set the TX config register. */
TXSTA = 0b00100000;
// ||||||||--bit0: TX9D = n/a
// |||||||---bit1: TRMT = ReadOnly
// ||||||----bit2: BRGH = High speed
// |||||-----bit3: SENDB = n/a
// ||||------bit4: SYNC = Asynchronous mode
// |||-------bit5: TXEN = Transmit enable
// ||--------bit6: TX9 = 8-bit transmission
// |---------bit7: CSRC = n/a
/* Set the Receive config register. */
RCSTA = 0b10010000;
// ||||||||--bit0: RX9D = ReadOnly
// |||||||---bit1: OERR = ReadOnly
// ||||||----bit2: FERR = ReadOnly
// |||||-----bit3: ADDEN = n/a
// ||||------bit4: CREN = Enable receiver
// |||-------bit5: SREN = n/a
// ||--------bit6: RX9 = 8-bit reception
// |---------bit7: SPEN = Serial port enabled
/* Calculate the baud rate generator value.
We use low-speed (BRGH=0), the formula is
SPBRG = ( ( FOSC / Desired Baud Rate ) / 64 ) - 1 */
usSPBRG = ( ( APROCFREQ / ulWantedBaud ) / 64 ) - 1;
if( usSPBRG > 255 )
{
SPBRG = 255;
}
else
{
SPBRG = usSPBRG;
}
/* Set the serial interrupts to use the same priority as the tick. */
bTXIP = serLOW_PRIORITY;
bRCIP = serLOW_PRIORITY;
/* Enable the Rx interrupt now, the Tx interrupt will get enabled when
we have data to send. */
bRCIE = serINTERRUPT_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;
}
/*-----------------------------------------------------------*/
xComPortHandle xSerialPortInit( eCOMPort ePort, eBaud eWantedBaud, eParity eWantedParity, eDataBits eWantedDataBits, eStopBits eWantedStopBits, unsigned char ucBufferLength )
{
/* This is not implemented in this port.
Use xSerialPortInitMinimal() instead. */
return NULL;
}
/*-----------------------------------------------------------*/
portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, 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 ( char ) pdTRUE;
}
return ( char ) pdFALSE;
}
/*-----------------------------------------------------------*/
portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, char cOutChar, TickType_t xBlockTime )
{
/* Return false if after the block time there is no room on the Tx queue. */
if( xQueueSend( xCharsForTx, ( const void * ) &cOutChar, xBlockTime ) != ( char ) pdPASS )
{
return pdFAIL;
}
/* Turn interrupt on - ensure the compiler only generates a single
instruction for this. */
bTXIE = serINTERRUPT_ENABLED;
return pdPASS;
}
/*-----------------------------------------------------------*/
void vSerialClose( xComPortHandle xPort )
{
/* Not implemented for this port.
To implement, turn off the interrupts and delete the memory
allocated to the queues. */
}
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