/* | |
* 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! | |
*/ | |
/* Scheduler includes. */ | |
#include "FreeRTOS.h" | |
#include "task.h" | |
#include "queue.h" | |
/* Demo includes. */ | |
#include "lcd.h" | |
/* | |
* The LCD is written to by more than one task so is controlled by this | |
* 'gatekeeper' task. This is the only task that is actually permitted to | |
* access the LCD directly. Other tasks wanting to display a message send | |
* the message to the gatekeeper. | |
*/ | |
static void vLCDTask( void *pvParameters ); | |
/* | |
* Setup the peripherals required to communicate with the LCD. | |
*/ | |
static void prvSetupLCD( void ); | |
/* | |
* Move to the first (0) or second (1) row of the LCD. | |
*/ | |
static void prvLCDGotoRow( unsigned short usRow ); | |
/* | |
* Write a string of text to the LCD. | |
*/ | |
static void prvLCDPutString( char *pcString ); | |
/* | |
* Clear the LCD. | |
*/ | |
static void prvLCDClear( void ); | |
/*-----------------------------------------------------------*/ | |
/* Brief delay to permit the LCD to catch up with commands. */ | |
#define lcdVERY_SHORT_DELAY ( 1 ) | |
#define lcdSHORT_DELAY ( 4 / portTICK_PERIOD_MS ) | |
#define lcdLONG_DELAY ( 15 / portTICK_PERIOD_MS ) | |
/* LCD commands. */ | |
#define lcdCLEAR ( 0x01 ) | |
#define lcdHOME ( 0x02 ) | |
#define lcdLINE2 ( 0xc0 ) | |
/* SFR that seems to be missing from the standard header files. */ | |
#define PMAEN *( ( unsigned short * ) 0x60c ) | |
/* LCD R/W signal. */ | |
#define lcdRW LATDbits.LATD5 | |
/* LCD lcdRS signal. */ | |
#define lcdRS LATBbits.LATB15 | |
/* LCD lcdE signal . */ | |
#define lcdE LATDbits.LATD4 | |
/* Control signal pin direction. */ | |
#define RW_TRIS TRISDbits.TRISD5 | |
#define RS_TRIS TRISBbits.TRISB15 | |
#define E_TRIS TRISDbits.TRISD4 | |
/* Port for LCD data */ | |
#define lcdDATA LATE | |
#define lcdDATAPORT PORTE | |
/* I/O setup for data Port. */ | |
#define TRISDATA TRISE | |
/* The length of the queue used to send messages to the LCD gatekeeper task. */ | |
#define lcdQUEUE_SIZE 3 | |
/*-----------------------------------------------------------*/ | |
/* The queue used to send messages to the LCD task. */ | |
QueueHandle_t xLCDQueue; | |
static void prvLCDCommand( char cCommand ); | |
static void prvLCDData( char cChar ); | |
/*-----------------------------------------------------------*/ | |
QueueHandle_t xStartLCDTask( void ) | |
{ | |
/* Create the queue used by the LCD task. Messages for display on the LCD | |
are received via this queue. */ | |
xLCDQueue = xQueueCreate( lcdQUEUE_SIZE, sizeof( xLCDMessage ) ); | |
/* Start the task that will write to the LCD. The LCD hardware is | |
initialised from within the task itself so delays can be used. */ | |
xTaskCreate( vLCDTask, "LCD", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY + 1, NULL ); | |
return xLCDQueue; | |
} | |
/*-----------------------------------------------------------*/ | |
static void prvLCDGotoRow( unsigned short usRow ) | |
{ | |
if( usRow == 0 ) | |
{ | |
prvLCDCommand( lcdHOME ); | |
} | |
else | |
{ | |
prvLCDCommand( lcdLINE2 ); | |
} | |
} | |
/*-----------------------------------------------------------*/ | |
static void prvLCDCommand( char cCommand ) | |
{ | |
/* Prepare RD0 - RD7. */ | |
lcdDATA &= 0xFF00; | |
/* Command byte to lcd. */ | |
lcdDATA |= cCommand; | |
/* Ensure lcdRW is 0. */ | |
lcdRW = 0; | |
lcdRS = 0; | |
/* Toggle lcdE line. */ | |
lcdE = 1; | |
vTaskDelay( lcdVERY_SHORT_DELAY ); | |
lcdE = 0; | |
vTaskDelay( lcdSHORT_DELAY ); | |
} | |
/*-----------------------------------------------------------*/ | |
static void prvLCDData( char cChar ) | |
{ | |
/* ensure lcdRW is 0. */ | |
lcdRW = 0; | |
/* Assert register select to 1. */ | |
lcdRS = 1; | |
/* Prepare RD0 - RD7. */ | |
lcdDATA &= 0xFF00; | |
/* Data byte to lcd. */ | |
lcdDATA |= cChar; | |
lcdE = 1; | |
Nop(); | |
Nop(); | |
Nop(); | |
/* Toggle lcdE signal. */ | |
lcdE = 0; | |
/* Negate register select to 0. */ | |
lcdRS = 0; | |
vTaskDelay( lcdVERY_SHORT_DELAY ); | |
} | |
/*-----------------------------------------------------------*/ | |
static void prvLCDPutString( char *pcString ) | |
{ | |
/* Write out each character with appropriate delay between each. */ | |
while( *pcString ) | |
{ | |
prvLCDData( *pcString ); | |
pcString++; | |
vTaskDelay( lcdSHORT_DELAY ); | |
} | |
} | |
/*-----------------------------------------------------------*/ | |
static void prvLCDClear( void ) | |
{ | |
prvLCDCommand( lcdCLEAR ); | |
} | |
/*-----------------------------------------------------------*/ | |
static void prvSetupLCD( void ) | |
{ | |
/* Wait for proper power up. */ | |
vTaskDelay( lcdLONG_DELAY ); | |
/* Set initial states for the data and control pins */ | |
LATE &= 0xFF00; | |
/* R/W state set low. */ | |
lcdRW = 0; | |
/* lcdRS state set low. */ | |
lcdRS = 0; | |
/* lcdE state set low. */ | |
lcdE = 0; | |
/* Set data and control pins to outputs */ | |
TRISE &= 0xFF00; | |
/* lcdRW pin set as output. */ | |
RW_TRIS = 0; | |
/* lcdRS pin set as output. */ | |
RS_TRIS = 0; | |
/* lcdE pin set as output. */ | |
E_TRIS = 0; | |
/* 1st LCD initialization sequence */ | |
lcdDATA &= 0xFF00; | |
lcdDATA |= 0x0038; | |
lcdE = 1; | |
Nop(); | |
Nop(); | |
Nop(); | |
/* Toggle lcdE signal. */ | |
lcdE = 0; | |
vTaskDelay( lcdSHORT_DELAY ); | |
vTaskDelay( lcdSHORT_DELAY ); | |
vTaskDelay( lcdSHORT_DELAY ); | |
/* 2nd LCD initialization sequence */ | |
lcdDATA &= 0xFF00; | |
lcdDATA |= 0x0038; | |
lcdE = 1; | |
Nop(); | |
Nop(); | |
Nop(); | |
/* Toggle lcdE signal. */ | |
lcdE = 0; | |
vTaskDelay( lcdSHORT_DELAY ); | |
/* 3rd LCD initialization sequence */ | |
lcdDATA &= 0xFF00; | |
lcdDATA |= 0x0038; | |
lcdE = 1; | |
Nop(); | |
Nop(); | |
Nop(); | |
/* Toggle lcdE signal. */ | |
lcdE = 0; | |
vTaskDelay( lcdSHORT_DELAY ); | |
/* Function set. */ | |
prvLCDCommand( 0x38 ); | |
/* Display on/off control, cursor blink off (0x0C). */ | |
prvLCDCommand( 0x0C ); | |
/* Entry mode set (0x06). */ | |
prvLCDCommand( 0x06 ); | |
prvLCDCommand( lcdCLEAR ); | |
} | |
/*-----------------------------------------------------------*/ | |
static void vLCDTask( void *pvParameters ) | |
{ | |
xLCDMessage xMessage; | |
unsigned short usRow = 0; | |
/* Initialise the hardware. This uses delays so must not be called prior | |
to the scheduler being started. */ | |
prvSetupLCD(); | |
/* Welcome message. */ | |
prvLCDPutString( "www.FreeRTOS.org" ); | |
for( ;; ) | |
{ | |
/* Wait for a message to arrive that requires displaying. */ | |
while( xQueueReceive( xLCDQueue, &xMessage, portMAX_DELAY ) != pdPASS ); | |
/* Clear the current display value. */ | |
prvLCDClear(); | |
/* Switch rows each time so we can see that the display is still being | |
updated. */ | |
prvLCDGotoRow( usRow & 0x01 ); | |
usRow++; | |
prvLCDPutString( xMessage.pcMessage ); | |
/* Delay the requested amount of time to ensure the text just written | |
to the LCD is not overwritten. */ | |
vTaskDelay( xMessage.xMinDisplayTime ); | |
} | |
} | |