/* | |
FreeRTOS V7.4.0 - Copyright (C) 2013 Real Time Engineers Ltd. | |
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*************************************************************************** | |
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*************************************************************************** | |
* * | |
* Having a problem? Start by reading the FAQ "My application does * | |
* not run, what could be wrong?" * | |
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* http://www.FreeRTOS.org/FAQHelp.html * | |
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*/ | |
/* | |
BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0. | |
*/ | |
/* Standard includes. */ | |
#include <stdlib.h> | |
/* Scheduler includes. */ | |
#include "FreeRTOS.h" | |
#include "queue.h" | |
#include "task.h" | |
/* Demo application includes. */ | |
#include "serial.h" | |
/*-----------------------------------------------------------*/ | |
/* Constants to setup and access the UART. */ | |
#define serDLAB ( ( unsigned char ) 0x80 ) | |
#define serENABLE_INTERRUPTS ( ( unsigned char ) 0x03 ) | |
#define serNO_PARITY ( ( unsigned char ) 0x00 ) | |
#define ser1_STOP_BIT ( ( unsigned char ) 0x00 ) | |
#define ser8_BIT_CHARS ( ( unsigned char ) 0x03 ) | |
#define serFIFO_ON ( ( unsigned char ) 0x01 ) | |
#define serCLEAR_FIFO ( ( unsigned char ) 0x06 ) | |
#define serWANTED_CLOCK_SCALING ( ( unsigned long ) 16 ) | |
/* Constants to setup and access the VIC. */ | |
#define serU0VIC_CHANNEL ( ( unsigned long ) 0x0006 ) | |
#define serU0VIC_CHANNEL_BIT ( ( unsigned long ) 0x0040 ) | |
#define serU0VIC_ENABLE ( ( unsigned long ) 0x0020 ) | |
#define serCLEAR_VIC_INTERRUPT ( ( unsigned long ) 0 ) | |
/* Constants to determine the ISR source. */ | |
#define serSOURCE_THRE ( ( unsigned char ) 0x02 ) | |
#define serSOURCE_RX_TIMEOUT ( ( unsigned char ) 0x0c ) | |
#define serSOURCE_ERROR ( ( unsigned char ) 0x06 ) | |
#define serSOURCE_RX ( ( unsigned char ) 0x04 ) | |
#define serINTERRUPT_SOURCE_MASK ( ( unsigned char ) 0x0f ) | |
/* Misc. */ | |
#define serINVALID_QUEUE ( ( xQueueHandle ) 0 ) | |
#define serHANDLE ( ( xComPortHandle ) 1 ) | |
#define serNO_BLOCK ( ( portTickType ) 0 ) | |
/*-----------------------------------------------------------*/ | |
/* Queues used to hold received characters, and characters waiting to be | |
transmitted. */ | |
static xQueueHandle xRxedChars; | |
static xQueueHandle xCharsForTx; | |
static volatile long lTHREEmpty = pdFALSE; | |
/*-----------------------------------------------------------*/ | |
/* The ISR. Note that this is called by a wrapper written in the file | |
SerialISR.s79. See the WEB documentation for this port for further | |
information. */ | |
__arm void vSerialISR( void ); | |
/*-----------------------------------------------------------*/ | |
xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength ) | |
{ | |
unsigned long ulDivisor, ulWantedClock; | |
xComPortHandle xReturn = serHANDLE; | |
extern void ( vSerialISREntry) ( void ); | |
/* Create the queues used to hold Rx and Tx characters. */ | |
xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) ); | |
xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) ); | |
/* Initialise the THRE empty flag. */ | |
lTHREEmpty = pdTRUE; | |
if( | |
( xRxedChars != serINVALID_QUEUE ) && | |
( xCharsForTx != serINVALID_QUEUE ) && | |
( ulWantedBaud != ( unsigned long ) 0 ) | |
) | |
{ | |
portENTER_CRITICAL(); | |
{ | |
/* Setup the baud rate: Calculate the divisor value. */ | |
ulWantedClock = ulWantedBaud * serWANTED_CLOCK_SCALING; | |
ulDivisor = configCPU_CLOCK_HZ / ulWantedClock; | |
/* Set the DLAB bit so we can access the divisor. */ | |
U0LCR |= serDLAB; | |
/* Setup the divisor. */ | |
U0DLL = ( unsigned char ) ( ulDivisor & ( unsigned long ) 0xff ); | |
ulDivisor >>= 8; | |
U0DLM = ( unsigned char ) ( ulDivisor & ( unsigned long ) 0xff ); | |
/* Turn on the FIFO's and clear the buffers. */ | |
U0FCR = ( serFIFO_ON | serCLEAR_FIFO ); | |
/* Setup transmission format. */ | |
U0LCR = serNO_PARITY | ser1_STOP_BIT | ser8_BIT_CHARS; | |
/* Setup the VIC for the UART. */ | |
VICIntSelect &= ~( serU0VIC_CHANNEL_BIT ); | |
VICIntEnable |= serU0VIC_CHANNEL_BIT; | |
VICVectAddr1 = ( unsigned long ) vSerialISREntry; | |
VICVectCntl1 = serU0VIC_CHANNEL | serU0VIC_ENABLE; | |
/* Enable UART0 interrupts. */ | |
U0IER |= serENABLE_INTERRUPTS; | |
} | |
portEXIT_CRITICAL(); | |
xReturn = ( xComPortHandle ) 1; | |
} | |
else | |
{ | |
xReturn = ( xComPortHandle ) 0; | |
} | |
return xReturn; | |
} | |
/*-----------------------------------------------------------*/ | |
signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime ) | |
{ | |
/* The port handle is not required as this driver only supports UART0. */ | |
( void ) pxPort; | |
/* 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; | |
} | |
} | |
/*-----------------------------------------------------------*/ | |
void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength ) | |
{ | |
signed char *pxNext; | |
/* NOTE: This implementation does not handle the queue being full as no | |
block time is used! */ | |
/* The port handle is not required as this driver only supports UART0. */ | |
( void ) pxPort; | |
( void ) usStringLength; | |
/* Send each character in the string, one at a time. */ | |
pxNext = ( signed char * ) pcString; | |
while( *pxNext ) | |
{ | |
xSerialPutChar( pxPort, *pxNext, serNO_BLOCK ); | |
pxNext++; | |
} | |
} | |
/*-----------------------------------------------------------*/ | |
signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime ) | |
{ | |
signed portBASE_TYPE xReturn; | |
/* The port handle is not required as this driver only supports UART0. */ | |
( void ) pxPort; | |
portENTER_CRITICAL(); | |
{ | |
/* Is there space to write directly to the UART? */ | |
if( lTHREEmpty == ( long ) pdTRUE ) | |
{ | |
/* We wrote the character directly to the UART, so was | |
successful. */ | |
lTHREEmpty = pdFALSE; | |
U0THR = cOutChar; | |
xReturn = pdPASS; | |
} | |
else | |
{ | |
/* We cannot write directly to the UART, so queue the character. | |
Block for a maximum of xBlockTime if there is no space in the | |
queue. It is ok to block within a critical section as each | |
task has it's own critical section management. */ | |
xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime ); | |
/* Depending on queue sizing and task prioritisation: While we | |
were blocked waiting to post interrupts were not disabled. It is | |
possible that the serial ISR has emptied the Tx queue, in which | |
case we need to start the Tx off again. */ | |
if( lTHREEmpty == ( long ) pdTRUE ) | |
{ | |
xQueueReceive( xCharsForTx, &cOutChar, serNO_BLOCK ); | |
lTHREEmpty = pdFALSE; | |
U0THR = cOutChar; | |
} | |
} | |
} | |
portEXIT_CRITICAL(); | |
return xReturn; | |
} | |
/*-----------------------------------------------------------*/ | |
__arm void vSerialISR( void ) | |
{ | |
signed char cChar; | |
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE; | |
/* What caused the interrupt? */ | |
switch( U0IIR & serINTERRUPT_SOURCE_MASK ) | |
{ | |
case serSOURCE_ERROR : /* Not handling this, but clear the interrupt. */ | |
cChar = U0LSR; | |
break; | |
case serSOURCE_THRE : /* The THRE is empty. If there is another | |
character in the Tx queue, send it now. */ | |
if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE ) | |
{ | |
U0THR = cChar; | |
} | |
else | |
{ | |
/* There are no further characters | |
queued to send so we can indicate | |
that the THRE is available. */ | |
lTHREEmpty = pdTRUE; | |
} | |
break; | |
case serSOURCE_RX_TIMEOUT : | |
case serSOURCE_RX : /* A character was received. Place it in | |
the queue of received characters. */ | |
cChar = U0RBR; | |
xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken ); | |
break; | |
default : /* There is nothing to do, leave the ISR. */ | |
break; | |
} | |
/* Exit the ISR. If a task was woken by either a character being received | |
or transmitted then a context switch will occur. */ | |
portEND_SWITCHING_ISR( xHigherPriorityTaskWoken ); | |
/* Clear the ISR in the VIC. */ | |
VICVectAddr = serCLEAR_VIC_INTERRUPT; | |
} | |
/*-----------------------------------------------------------*/ |