Subject:
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Solved?? rotation sensor problem.
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Fri, 10 Sep 1999 03:44:39 GMT
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Viewed:
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1021 times
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I tried solutions posted on this newsgroup to fix the rotation sensor
problem.But It didn't work stable enough.
I tracked the sensor input and realized the sensor sometimes picked up
transient signal between two states.
To solve this problem, I modified 'ds_rotation_handler()' to process sensor
values in two separete IRQ cycles.
1st cycle: Detect state change.
2nd cycle: Determine the new state.
The macro 'CURRENT_STATE' in my sample is based on
http://graphics.stanford.edu/~kekoa/rcx/index.html#Rom
--------------
I found a problem in a sample code 'demo/rotation-sensor.c'
It determines the initial state before a sensor actually becomes active.
ds_active(&SENSOR_3);
msleep(10); << I put short delay here.
ds_rotation_set(&SENSOR_3,0);
ds_rotation_on(&SENSOR_3);
------------- direct-sensor.c ---------------
-------- new variable
static char StateChanged[3]; // State changing flag (1999.9.3 by Abuku)
-------- macros
/*** 1999.9.3 by Abuku
//! A/D values for the rotation sensor states
#define RANGE_SIZE (ds_unscale( 40U))
#define STATE_0_VALUE (ds_unscale(1023U))
#define STATE_1_VALUE (ds_unscale( 833U))
#define STATE_2_VALUE (ds_unscale( 405U))
#define STATE_3_VALUE (ds_unscale( 623U))
//! rotation sensor range matching function
//
#define IN_RANGE( val ) (raw > (val - RANGE_SIZE) && \
raw < (val + RANGE_SIZE) )
*/
// Determine current state 1999.9.2 by Abuku.
#define CURRENT_STATE
(raw<0x6fc0?STATE_0:(raw<0xafc0?STATE_1:(raw<0xefc0?STATE_2:STATE_3)))
// Delay for final determination. (number of IRQ cycles) 1999.9.3 by Abuku
#define SAMPLING_WAIT 1
-------- in void ds_rotation_set()
if(sensor>=&AD_A && sensor<=&AD_C) { // catch range violations
/**** 1999.9.3 by abuku
if (raw <= STATE_2_VALUE ) // determine current state
state=STATE_2;
else if ( raw <= STATE_3_VALUE )
state=STATE_3;
else if ( raw <= STATE_1_VALUE )
state=STATE_1;
else
state=STATE_0;
*/
state = CURRENT_STATE; // Determine the initial state. 1999.9.2
by Abuku
StateChanged[channel] = 0; // 1999.9.3 by Abuku
-------- in void ds_rotation_handler()
/***** 1999.9.3 by Abuku
switch(state) {
case STATE_0:
if ( IN_RANGE ( STATE_3_VALUE ) ) {
state=STATE_3;
cooked--;
:
:
:
cooked++;
} else if( IN_RANGE ( STATE_2_VALUE ) ) {
state=STATE_2;
cooked--;
}
break;
}
*/
//*** 1999.9.3 by Abuku.
RotationState current_state = CURRENT_STATE;
if(StateChanged[channel] == 0) { // Not triggered ?
if(state != current_state) // State has changed ?
StateChanged[channel]++;
return;
}
else { // Already triggered
if(StateChanged[channel]++ < SAMPLING_WAIT) // Update the flag
return; // Keep waiting
StateChanged[channel] = 0; // Clear the flag
}
switch(state) { // Update state and angle value
// 0 <- +> 1 <- +> 3 <- +> 2
<- +> 0
case STATE_0:
if ( current_state == STATE_2 ) {
state=STATE_2;
cooked--;
} else if ( current_state == STATE_1 ) {
state=STATE_1;
cooked++;
}
break;
case STATE_1:
if ( current_state == STATE_0 ) {
state=STATE_0;
cooked--;
} else if( current_state == STATE_3 ) {
state=STATE_3;
cooked++;
}
break;
case STATE_2:
if ( current_state == STATE_0 ) {
state=STATE_0;
cooked++;
} else if ( current_state == STATE_3 ) {
state=STATE_3;
cooked--;
}
break;
case STATE_3:
if ( current_state == STATE_2 ) {
state=STATE_2;
cooked++;
} else if( current_state == STATE_1 ) {
state=STATE_1;
cooked--;
}
break;
}
// END modification. 1999.9.3 by Abuku
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