RTEC-0.3 - a concurrent realtime task system
############################################
1. Changes to RTEC-0.2:
2. Introduction
3. API description
4. Download
5. Installation
1. Changes to RTEC-0.2:
=======================
o Timing Bugfix
o Added soft-interrupt support
o rearranged the core (rt_core.c)
o created a better understandable demo (rt_application.c)
o more convenient "API"
2. Introduction
===============
RTEC is a try to port RTLinux to uClinux.
Actually, there is no priority task-scheduler,
but you can have up to 16 concurrent periodic
tasks (only limited by #define) running
at a desired periodizity. Every task has
it's own stack, currently limited to 16KB
(hardcoded). This is the basis for
a scheduler.
Additionaly, you can send an emulated interrupt
to the standard linux kernel. This is the
basis for a FIFO-handler (dev/rtf*).
Currently, the system is limited to MC68328.
3. API decription
=================
There are only a view functions that are interessting
for the user:
RT-Task handling:
-----------------
void rt_task_create(RTTASK *task,void (*code)(void),int add_to_list);
void rt_task_sleep(void);
void rt_start_concurrent_task_system(hrtime_t period);
void rt_switch_to_task(RTTASK *new_task);
RT-Interrupt handling:
----------------------
int rt_request_irq(unsigned int irq, void (*handler)(void));
void rt_free_irq(unsigned int irq);
Soft-Interrupt handling:
------------------------
void rt_pend_soft_irq(irq)
void rt_reset_soft_irq(irq)
Have a look at the Demo-Application to understand
for what these functions are used for:
/* ../linux/arch/m68knommu/platform/68328/rt_application.c */
#include <asm/system.h>
#include <asm/MC68328.h>
#include <linux/rtl.h>
#include <linux/sched.h>
#include <asm/irq.h>
unsigned long fb_data[160][5];
/* -------- soft interrupt emulation --------- */
#define MY_SOFT_RT_IRQ_NUM 31
int my_soft_rt_irq_handler(int vec, struct pt_regs *fp) {
printk("soft irq occured\n");
rt_reset_soft_irq(MY_SOFT_RT_IRQ_NUM);
return 0;
};
/* rt-handler for pen */
void rt_pen_demo(void) {
/* just do something */
fb_data[20][2]--;
/* pen-irq doesn't seem to be resetable ? */
/* send software interrupt to linux kernel */
rt_pend_soft_irq(MY_SOFT_RT_IRQ_NUM);
};
/* --------- concurrent task system demo ----------- */
RTTASK rt_listed_task1,rt_listed_task2;
RTTASK rt_circular_task1,rt_circular_task2;
/* this two "listed" tasks will be
called every 2 ms automaticaly */
void rt_listed_task1_code(void) {
while(1) {
fb_data[5][0]--;
rt_task_sleep();
};
};
void rt_listed_task2_code(void) {
while(1) {
rt_switch_to_task(&rt_circular_task1);
};
};
/* circular_task1 will be started by rt_listed_task2.
circular_task2 will be started by rt_circular_task1.
circular_task2 will go back to rtlinuxtask */
void rt_circular_task1_code(void) {
while(1) {
fb_data[5][2]++;
rt_switch_to_task(&rt_circular_task2);
};
};
void rt_circular_task2_code(void) {
while(1) {
fb_data[5][4]-=5000;
rt_switch_to_task(&rtlinuxtask);
};
};
/* -------------- init ------------- */
void rt_init_app(void) {
/* set LCD-Display output area */
LSSA = fb_data;
/* request handler for pen-interrupt */
rt_request_irq(PEN_IRQ_NUM,rt_pen_demo);
rt_task_create(&rt_listed_task1,rt_listed_task1_code,1);
rt_task_create(&rt_listed_task2,rt_listed_task2_code,1);
rt_task_create(&rt_circular_task1,rt_circular_task1_code,0);
rt_task_create(&rt_circular_task2,rt_circular_task2_code,0);
request_irq(IRQ_MACHSPEC | MY_SOFT_RT_IRQ_NUM, my_soft_rt_irq_handler,
IRQ_FLG_LOCK, "my_irq", NULL);
/* start timer1 and request handler */
rt_start_concurrent_task_system(2000000); /* 2ms */
};
4. Download
===========
This is a patch against uClinux-2.0.38.1pre1:
wget http://www.rcs.ei.tum.de/~kuhn/uclinux/uClinux-2.0.38.1pre1_rt-0.3.diff.gz
5. Installation
===============
Just unpack a clean linux-2.0.38 and patch it with uClinux-2.0.38.1pre1
and then apply the patch above.
For a more detailed installation instruction, refer to
the readme-file of rtec-0.1:
wget http://www.rcs.ei.tum.de/~kuhn/uclinux/rtec-0.1.txt
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----
For more information on Real-Time Linux see:
http://www.rtlinux.org/~rtlinux/
