Subject:
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Kernel freeze when attempting to use rotation sensor
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Sat, 12 Jun 2010 10:18:28 GMT
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Viewed:
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32206 times
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Hi,
I've tried using the latest BrickOS and the latest BIBO with patches (from here:
http://sourceforge.net/tracker/?func=detail&aid=2858992&group_id=58151&atid=486699
), both with the same result. I don't know if nobody's really used a rotation
sensor in 4 years (unlikely), or if my code just fails (likely), but every time
I run it, the kernel crashes when using the rotation sensor the SECOND TIME
AROUND (NOT THE FIRST TIME). The code in its entirety is posted below (it's for
a slightly modified version of the Plotter from the Ultimate Builders' Set):
#include <dmotor.h>
#include <dsensor.h>
#include <unistd.h>
#include <conio.h>
#include <lnp.h>
int charpos;
int line;
#define PAPER_WIDTH 10
#define PAPER_HEIGHT 13
void fosrotate(int drotations){ // Counts rotations using the Fibre Optic
System, which actually works rather well as a rotation sensor.
unsigned int rotations = 0;
while(rotations<drotations){
while(SENSOR_2!=0xFFC0){
}
rotations += 1;
while(SENSOR_2>0x9000){
}
rotations += 1;
}
}
void up(int x){ // Paper down x/16 teeth (no typo - pen goes up paper)
ds_rotation_on(&SENSOR_1);
ds_rotation_set(&SENSOR_1,0);
msleep(100);
motor_b_speed(MAX_SPEED);
motor_b_dir(rev);
while(ROTATION_1>-x){
msleep(100);
lcd_number(ROTATION_1,sign,e0);
}
motor_b_dir(brake);
ds_rotation_off(&SENSOR_1);
}
void down(int x){ // Paper up x/16 teeth (no typo - pen goes down paper)
ds_rotation_on(&SENSOR_1);
ds_rotation_set(&SENSOR_1,0);
msleep(100);
motor_b_speed(MAX_SPEED);
motor_b_dir(fwd);
while(ROTATION_1<x){
msleep(100);
lcd_number(ROTATION_1,sign,e0);
}
motor_b_dir(brake);
ds_rotation_off(&SENSOR_1);
}
void left(int x){ // Pen left x/16
motor_c_dir(rev);
fosrotate(x);
motor_c_dir(brake);
}
void right(int x){ // Pen right x/16 teeth
motor_c_dir(fwd);
fosrotate(x);
motor_c_dir(brake);
}
void pup(){
motor_a_dir(fwd);
sleep(7);
motor_a_dir(brake);
}
void pdown(){
motor_a_dir(rev);
sleep(12);
motor_a_dir(brake);
}
void cr(){
// Carriage to far left
motor_c_speed(MAX_SPEED);
motor_c_dir(rev);
msleep(500);
while(!TOUCH_3){
msleep(100);
}
// Carriage to print position (2 teeth right)
// motor_c_dir(fwd);
// fosrotate(32);
// motor_c_dir(brake);
right(32);
charpos = 0;
}
void lf(){
// Feed paper for a whole rotation of the output axle (24 * 16)
// ds_rotation_set(&SENSOR_1,0);
// ds_rotation_on(&SENSOR_1);
// motor_b_speed(MAX_SPEED);
// motor_b_dir(fwd);
// while(ROTATION_1<384){
// msleep(100);
// }
// motor_b_dir(brake);
down(100);
line += 1;
if(line > PAPER_HEIGHT){
cputc_native_user(CHAR_P, CHAR_C, CHAR_L, CHAR_A);
cputc_native_5(CHAR_4);
while(getchar() != KEY_VIEW){
}
line = 0;
lf();
}
}
void draw_a_letter(char letter){
if(letter == 10){ // LF
lf();
return;
}
if(letter == 13){ // CR
cr();
return;
}
if(letter == 'A'){
pdown();
down(80);
up(80);
right(40);
down(40);
left(50);
right(50);
down(40);
pup();
up(80);
right(10);
return;
}
}
void addr_handler_1(const unsigned char *data, unsigned char length, unsigned
char src)
{
int i;
for(i=0;i<length;++i){ // Print
draw_a_letter(data[i]);
}
}
int main(){
line = 0;
ds_active(&SENSOR_1);
ds_active(&SENSOR_2);
ds_passive(&SENSOR_3);
// Do initial Penup, CRLF
pup();
cr();
lf();
// Wait for message from PC
lnp_addressing_set_handler (0, addr_handler_1);
while(!shutdown_requested())
msleep(1000);
return 0;
}
I send the letter "A" from the computer and it receives fine. However, when
running the first down(80); instruction, the screen usually shows around 105
(note the lcd_number debug statements) and it completely freezes, with the motor
still running - only taking the battery out and redownloading the kernel will
get it back to normal. Note that this is the second time down(int x) has been
called - the initial CRLF (the LF in particular) calls down(100).
It seems to me that the code to set the rotation sensor's value to 0 doesn't
actually work, and instead freezes the kernel. Anyone else got any clues?
Thanks in advance for any help,
Muzer (Murray Colpman).
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