On télécharge la dernière version de FreeRTOS depuis sa page de téléchargement. Lors de la rédaction de cet article, il s'agit de la version 7.1.0.
On décompresse l'archive téléchargée dans le dossier /home/idreammicro/workspace/helloworld_freertos. On ne conservera que les dossiers FreeRTOS/Source, FreeRTOS/License et le fichier FreeRTOS/readme.txt.
Portage
Le portage pour ATmega323 servant de base, on copie le dossier FreeRTOS/Source/portable/GCC/ATMega323 vers le dossier FreeRTOS/Source/portable/GCC/ATMega328.
Les modifications portent essentiellement sur le fichier FreeRTOS/Source/portable/GCC/ATMega328/port.c afin de s'adapter à son Timer 1 (constantes, registres, vecteur d'interruption).
Constantes
Quelques constantes nécessitent d'être redéfinies. Il est également judicieux de remplacer les nombres magiques de certaines par les noms des bits concernés :
- portCLEAR_COUNTER_ON_MATCH (ligne 77) ;
- portPRESCALE_64 (ligne 78) ;
- portCOMPARE_MATCH_A_INTERRUPT_ENABLE (ligne 80).
/*----------------------------------------------------------- * Implementation of functions defined in portable.h for the AVR port. *----------------------------------------------------------*/ /* Start tasks with interrupts enables. */ #define portFLAGS_INT_ENABLED ( ( portSTACK_TYPE ) 0x80 ) /* Hardware constants for timer 1. */ #define portCLEAR_COUNTER_ON_MATCH ( ( unsigned char ) _BV(WGM12) ) #define portPRESCALE_64 ( ( unsigned char ) (_BV(CS11) | _BV(CS10)) ) #define portCLOCK_PRESCALER ( ( unsigned long ) 64 ) #define portCOMPARE_MATCH_A_INTERRUPT_ENABLE ( ( unsigned char ) _BV(OCIE1A) )
Configuration du Timer 1
Par rapport à l'ATmega323, les noms des registres du Timer 1 de l'ATmega328 diffèrent quelque peu. Aussi, quelques simplifications peuvent être effectuées :
- configuration de la valeur de comparaison du Timer 1 directement dans le registre 16 bits OCR1A (ligne 407) ;
- initialisation de la valeur du registre TCCR1A (ligne 407) ;
- le registre TIMSK devient TIMSK1 (lignes 413 et 415) ;
- suppression de la variable ucHighByte désormais inutilisée (ligne 389).
/*
* Setup timer 1 compare match A to generate a tick interrupt.
*/
static void prvSetupTimerInterrupt( void )
{
unsigned long ulCompareMatch;
unsigned char ucLowByte;
/* Using 16bit timer 1 to generate the tick. Correct fuses must be
selected for the configCPU_CLOCK_HZ clock. */
ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ;
/* We only have 16 bits so have to scale to get our required tick rate. */
ulCompareMatch /= portCLOCK_PRESCALER;
/* Adjust for correct value. */
ulCompareMatch -= ( unsigned long ) 1;
/* Setup compare match value for compare match A. Interrupts are disabled
before this is called so we need not worry here. */
OCR1A = ulCompareMatch;
/* Setup clock source and compare match behaviour. */
TCCR1A &= ~(_BV(WGM11) | _BV(WGM10));;
ucLowByte = portCLEAR_COUNTER_ON_MATCH | portPRESCALE_64;
TCCR1B = ucLowByte;
/* Enable the interrupt - this is okay as interrupt are currently globally
disabled. */
ucLowByte = TIMSK1;
ucLowByte |= portCOMPARE_MATCH_A_INTERRUPT_ENABLE;
TIMSK1 = ucLowByte;
}
Routine d'interruption du Timer 1
Par rapport à l'ATmega323, le nom du vecteur d'interruption du Timer 1 de l'ATmega328 évolue. On remplacera donc SIG_OUTPUT_COMPARE1A par TIMER1_COMPA_vect (lignes 426, 427, 439 et 440).
#if configUSE_PREEMPTION == 1
/*
* Tick ISR for preemptive scheduler. We can use a naked attribute as
* the context is saved at the start of vPortYieldFromTick(). The tick
* count is incremented after the context is saved.
*/
void TIMER1_COMPA_vect( void ) __attribute__ ( ( signal, naked ) );
void TIMER1_COMPA_vect( void )
{
vPortYieldFromTick();
asm volatile ( "reti" );
}
#else
/*
* Tick ISR for the cooperative scheduler. All this does is increment the
* tick count. We don't need to switch context, this can only be done by
* manual calls to taskYIELD();
*/
void TIMER1_COMPA_vect( void ) __attribute__ ( ( signal ) );
void TIMER1_COMPA_vect( void )
{
vTaskIncrementTick();
}
#endif
Finalisation
Il est nécessaire de modifier le fichier FreeRTOS/Source/include/portable.h. Si le microcontrôleur est un ATmega328, on utilise le portage que l'on vient de créer. Sinon on utilise le portage pour ATmega323.
#ifdef GCC_MEGA_AVR
#if defined (__AVR_ATmega328P__) || defined (__AVR_ATmega328__)
#include "../portable/GCC/ATMega328/portmacro.h"
#else
#include "../portable/GCC/ATMega323/portmacro.h"
#endif
#endif
Projet de test
Fichier FreeRTOSConfig.h
On crée un fichier FreeRTOSConfig.h à la racine du dossier du projet. On prendra pour modèle le fichier du projet de démonstration livré avec FreeRTOS.
La fréquence d'horloge du microcontrôleur est indiquée par la constante F_CPU plutôt que par une valeur (ligne 74). D'autant plus que cette constante est très largement utilisée. Les autres constantes demeurerons telles quelles, libre à chacun de les ajuster en fonction de son projet.
/*----------------------------------------------------------- * Application specific definitions. * * These definitions should be adjusted for your particular hardware and * application requirements. * * THESE PARAMETERS ARE DESCRIBED WITHIN THE 'CONFIGURATION' SECTION OF THE * FreeRTOS API DOCUMENTATION AVAILABLE ON THE FreeRTOS.org WEB SITE. * * See http://www.freertos.org/a00110.html. *----------------------------------------------------------*/ #define configUSE_PREEMPTION 1 #define configUSE_IDLE_HOOK 1 #define configUSE_TICK_HOOK 0 #define configCPU_CLOCK_HZ ( ( unsigned long ) F_CPU ) #define configTICK_RATE_HZ ( ( portTickType ) 1000 ) #define configMAX_PRIORITIES ( ( unsigned portBASE_TYPE ) 4 ) #define configMINIMAL_STACK_SIZE ( ( unsigned short ) 85 ) #define configTOTAL_HEAP_SIZE ( (size_t ) ( 1500 ) ) #define configMAX_TASK_NAME_LEN ( 8 ) #define configUSE_TRACE_FACILITY 0 #define configUSE_16_BIT_TICKS 1 #define configIDLE_SHOULD_YIELD 1 #define configQUEUE_REGISTRY_SIZE 0 /* Co-routine definitions. */ #define configUSE_CO_ROUTINES 1 #define configMAX_CO_ROUTINE_PRIORITIES ( 2 ) /* Set the following definitions to 1 to include the API function, or zero to exclude the API function. */ #define INCLUDE_vTaskPrioritySet 0 #define INCLUDE_uxTaskPriorityGet 0 #define INCLUDE_vTaskDelete 1 #define INCLUDE_vTaskCleanUpResources 0 #define INCLUDE_vTaskSuspend 0 #define INCLUDE_vTaskDelayUntil 1 #define INCLUDE_vTaskDelay 1
Fichier source
On crée un fichier main.c à la racine du dossier du projet.
Le programme de test fait basculer le niveau de la sortie PB5 toute les 500 ms :
- fonction de configuration et de basculement du niveau de sortie de PB5 (lignes 74 à 83) ;
- création de la tâche (lignes 36 à 45) ;
- démarrage de l'ordonnanceur (ligne 48).
/******************************************************************************
* Header file inclusions.
******************************************************************************/
#include "FreeRTOS.h"
#include "task.h"
#include <avr/io.h>
/******************************************************************************
* Private macro definitions.
******************************************************************************/
#define mainLED_TASK_PRIORITY (tskIDLE_PRIORITY)
/******************************************************************************
* Private function prototypes.
******************************************************************************/
static void vBlinkLed(void* pvParameters);
/******************************************************************************
* Public function definitions.
******************************************************************************/
/**************************************************************************//**
* \fn int main(void)
*
* \brief Main function.
*
* \return
******************************************************************************/
int main(void)
{
// Create task.
xTaskHandle blink_handle;
xTaskCreate
(
vBlinkLed,
(signed char*)"blink",
configMINIMAL_STACK_SIZE,
NULL,
mainLED_TASK_PRIORITY,
&blink_handle
);
// Start scheduler.
vTaskStartScheduler();
return 0;
}
/**************************************************************************//**
* \fn static vApplicationIdleHook(void)
*
* \brief
******************************************************************************/
void vApplicationIdleHook(void)
{
}
/******************************************************************************
* Private function definitions.
******************************************************************************/
/**************************************************************************//**
* \fn static void vBlinkLed(void* pvParameters)
*
* \brief
*
* \param[in] pvParameters
******************************************************************************/
static void vBlinkLed(void* pvParameters)
{
DDRB |= _BV(PB5);
for ( ;; )
{
PORTB ^= _BV(PB5);
vTaskDelay(500);
}
}
Makefile
On crée un fichier makefile permettant de construire le projet. On prendra pour modèle le fichier du projet de démonstration livré avec FreeRTOS.
# WinAVR Sample makefile written by Eric B. Weddington, Jörg Wunsch, et al. # Released to the Public Domain # Please read the make user manual! # # Additional material for this makefile was submitted by: # Tim Henigan # Peter Fleury # Reiner Patommel # Sander Pool # Frederik Rouleau # Markus Pfaff # # On command line: # # make all = Make software. # # make clean = Clean out built project files. # # make program = Download the hex file to the device, using avrdude. Please # customize the avrdude settings below first! # # make filename.s = Just compile filename.c into the assembler code only # # To rebuild project do "make clean" then "make all". # # MCU name MCU = atmega328p # Output format. (can be srec, ihex, binary) FORMAT = ihex # Target file name (without extension). TARGET = helloworld_freertos # Optimization level, can be [0, 1, 2, 3, s]. 0 turns off optimization. # (Note: 3 is not always the best optimization level. See avr-libc FAQ.) OPT = s # List C source files here. (C dependencies are automatically generated.) SOURCE_DIR = FreeRTOS/Source PORT_DIR = FreeRTOS/Source/portable/GCC/ATMega328 SRC = \ main.c \ $(SOURCE_DIR)/tasks.c \ $(SOURCE_DIR)/queue.c \ $(SOURCE_DIR)/list.c \ $(SOURCE_DIR)/croutine.c \ $(SOURCE_DIR)/portable/MemMang/heap_1.c \ $(PORT_DIR)/port.c # Optional compiler flags. # -g: generate debugging information (for GDB, or for COFF conversion) # -O*: optimization level # -f...: tuning, see gcc manual and avr-libc documentation # -Wall...: warning level # -Wa,...: tell GCC to pass this to the assembler. # -ahlms: create assembler listing DEBUG_LEVEL=-g WARNINGS=-Wall -Wextra -Wshadow -Wpointer-arith -Wbad-function-cast -Wcast-align -Wsign-compare \ -Waggregate-return -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wunused CFLAGS = -D GCC_MEGA_AVR -D F_CPU=16000000 -I. -IFreeRTOS/Source/include -IFreeRTOS/Source/portable/GCC/ATMega328 \ $(DEBUG_LEVEL) -O$(OPT) \ -fsigned-char -funsigned-bitfields -fpack-struct -fshort-enums \ $(WARNINGS) \ -Wa,-adhlns=$(<:.c=.lst) \ $(patsubst %,-I%,$(EXTRAINCDIRS)) # Set a "language standard" compiler flag. # Unremark just one line below to set the language standard to use. # gnu99 = C99 + GNU extensions. See GCC manual for more information. CFLAGS += -std=gnu99 # Optional assembler flags. # -Wa,...: tell GCC to pass this to the assembler. # -ahlms: create listing # -gstabs: have the assembler create line number information; note that # for use in COFF files, additional information about filenames # and function names needs to be present in the assembler source # files -- see avr-libc docs [FIXME: not yet described there] ASFLAGS = -Wa,-adhlns=$(<:.S=.lst),-gstabs # Optional linker flags. # -Wl,...: tell GCC to pass this to linker. # -Map: create map file # --cref: add cross reference to map file LDFLAGS = -Wl,-Map=$(TARGET).map,--cref # Additional libraries # Minimalistic printf version #LDFLAGS += -Wl,-u,vfprintf -lprintf_min # Floating point printf version (requires -lm below) #LDFLAGS += -Wl,-u,vfprintf -lprintf_flt # -lm = math library #LDFLAGS += -lm # Programming support using avrdude. Settings and variables. # Programming hardware: alf avr910 avrisp bascom bsd # dt006 pavr picoweb pony-stk200 sp12 stk200 stk500 # # Type: avrdude -c ? # to get a full listing. # AVRDUDE_PROGRAMMER = arduino AVRDUDE_PORT = /dev/ttyACM0 AVRDUDE_WRITE_FLASH = -U flash:w:$(TARGET).hex AVRDUDE_FLAGS = -p $(MCU) -P $(AVRDUDE_PORT) -c $(AVRDUDE_PROGRAMMER) # Uncomment the following if you want avrdude's erase cycle counter. # Note that this counter needs to be initialized first using -Yn, # see avrdude manual. #AVRDUDE_ERASE += -y # Uncomment the following if you do /not/ wish a verification to be # performed after programming the device. #AVRDUDE_FLAGS += -V # Increase verbosity level. Please use this when submitting bug # reports about avrdude. See <http://savannah.nongnu.org/projects/avrdude> # to submit bug reports. #AVRDUDE_FLAGS += -v -v # --------------------------------------------------------------------------- # Define directories, if needed. DIRAVR = c:/winavr DIRAVRBIN = $(DIRAVR)/bin DIRAVRUTILS = $(DIRAVR)/utils/bin DIRINC = . DIRLIB = $(DIRAVR)/avr/lib # Define programs and commands. SHELL = sh CC = avr-gcc OBJCOPY = avr-objcopy OBJDUMP = avr-objdump SIZE = avr-size # Programming support using avrdude. AVRDUDE = avrdude REMOVE = rm -f COPY = cp HEXSIZE = $(SIZE) --target=$(FORMAT) $(TARGET).hex ELFSIZE = $(SIZE) -A $(TARGET).elf # Define Messages # English MSG_ERRORS_NONE = Errors: none MSG_BEGIN = -------- begin -------- MSG_END = -------- end -------- MSG_SIZE_BEFORE = Size before: MSG_SIZE_AFTER = Size after: MSG_COFF = Converting to AVR COFF: MSG_EXTENDED_COFF = Converting to AVR Extended COFF: MSG_FLASH = Creating load file for Flash: MSG_EEPROM = Creating load file for EEPROM: MSG_EXTENDED_LISTING = Creating Extended Listing: MSG_SYMBOL_TABLE = Creating Symbol Table: MSG_LINKING = Linking: MSG_COMPILING = Compiling: MSG_ASSEMBLING = Assembling: MSG_CLEANING = Cleaning project: # Define all object files. OBJ = $(SRC:.c=.o) $(ASRC:.S=.o) # Define all listing files. LST = $(ASRC:.S=.lst) $(SRC:.c=.lst) # Combine all necessary flags and optional flags. # Add target processor to flags. ALL_CFLAGS = -mmcu=$(MCU) -I. $(CFLAGS) ALL_ASFLAGS = -mmcu=$(MCU) -I. -x assembler-with-cpp $(ASFLAGS) # Default target. all: begin gccversion sizebefore $(TARGET).elf $(TARGET).hex $(TARGET).eep \ $(TARGET).lss $(TARGET).sym sizeafter finished end # Eye candy. # AVR Studio 3.x does not check make's exit code but relies on # the following magic strings to be generated by the compile job. begin: @echo @echo $(MSG_BEGIN) finished: @echo $(MSG_ERRORS_NONE) end: @echo $(MSG_END) @echo # Display size of file. sizebefore: @if [ -f $(TARGET).elf ]; then echo; echo $(MSG_SIZE_BEFORE); $(ELFSIZE); echo; fi sizeafter: @if [ -f $(TARGET).elf ]; then echo; echo $(MSG_SIZE_AFTER); $(ELFSIZE); echo; fi # Display compiler version information. gccversion : @$(CC) --version # Program the device. program: $(TARGET).hex $(TARGET).eep $(AVRDUDE) $(AVRDUDE_FLAGS) $(AVRDUDE_WRITE_FLASH) $(AVRDUDE_WRITE_EEPROM) # Create final output files (.hex, .eep) from ELF output file. %.hex: %.elf @echo @echo $(MSG_FLASH) $@ $(OBJCOPY) -O $(FORMAT) -R .eeprom $< $@ %.eep: %.elf @echo @echo $(MSG_EEPROM) $@ -$(OBJCOPY) -j .eeprom --set-section-flags=.eeprom="alloc,load" \ --change-section-lma .eeprom=0 -O $(FORMAT) $< $@ # Create extended listing file from ELF output file. %.lss: %.elf @echo @echo $(MSG_EXTENDED_LISTING) $@ $(OBJDUMP) -h -S $< > $@ # Create a symbol table from ELF output file. %.sym: %.elf @echo @echo $(MSG_SYMBOL_TABLE) $@ avr-nm -n $< > $@ # Link: create ELF output file from object files. .SECONDARY : $(TARGET).elf .PRECIOUS : $(OBJ) %.elf: $(OBJ) @echo @echo $(MSG_LINKING) $@ $(CC) $(ALL_CFLAGS) $(OBJ) --output $@ $(LDFLAGS) # Compile: create object files from C source files. %.o : %.c @echo @echo $(MSG_COMPILING) $< $(CC) -c $(ALL_CFLAGS) $< -o $@ # Compile: create assembler files from C source files. %.s : %.c $(CC) -S $(ALL_CFLAGS) $< -o $@ # Assemble: create object files from assembler source files. %.o : %.S @echo @echo $(MSG_ASSEMBLING) $< $(CC) -c $(ALL_ASFLAGS) $< -o $@ # Target: clean project. clean: begin clean_list finished end clean_list : @echo @echo $(MSG_CLEANING) $(REMOVE) $(TARGET).hex $(REMOVE) $(TARGET).eep $(REMOVE) $(TARGET).obj $(REMOVE) $(TARGET).cof $(REMOVE) $(TARGET).elf $(REMOVE) $(TARGET).map $(REMOVE) $(TARGET).obj $(REMOVE) $(TARGET).a90 $(REMOVE) $(TARGET).sym $(REMOVE) $(TARGET).lnk $(REMOVE) $(TARGET).lss $(REMOVE) $(OBJ) $(REMOVE) $(LST) $(REMOVE) $(SRC:.c=.s) $(REMOVE) $(SRC:.c=.d) # Automatically generate C source code dependencies. # (Code originally taken from the GNU make user manual and modified # (See README.txt Credits).) # # Note that this will work with sh (bash) and sed that is shipped with WinAVR # (see the SHELL variable defined above). # This may not work with other shells or other seds. # %.d: %.c set -e; $(CC) -MM $(ALL_CFLAGS) $< \ | sed 's,\(.*\)\.o[ :]*,\1.o \1.d : ,g' > $@; \ [ -s $@ ] || rm -f $@ # Remove the '-' if you want to see the dependency files generated. -include $(SRC:.c=.d) # Listing of phony targets. .PHONY : all begin finish end sizebefore sizeafter gccversion coff extcoff \ clean clean_list program
Compilation du projet
On se place dans le dossier /home/idreammicro/workspace/helloworld_freertos :
$ cd /home/idreammicro/workspace/helloworld_freertos
On ordonne la compilation du projet :
$ make
Téléchargement du fichier binaire
Le makefile peut assurer la programmation du microcontrôleur :
$ make program
Et un portage pour ATmega328, un !
La LED connectée sur la sortie PB5 clignote toutes les 500 ms ? Félicitations, le portage de FreeRTOS sur ATmega328 fonctionne !
Comme l'a montré cet article, porter FreeRTOS est relativement simple. Ce portage est très probablement valable pour d'autres microcontrôleurs de la famille ATmega. Dans le cas contraire, il suffit de reproduire la même démarche tout en s'adaptant au nouveau microcontrôleur à supporter.
une réaction
1 De Carlos - 31/03/2015, 12:51
Awesome work!
I'll use your port in my master thesis project.
Thank you very much :D