De-bouncing rotary switch with gray encoding in C
$begingroup$
I would like feedback on the correctness and performance of this code.
My priorities are also are readability, simplicity and self-documenting code - but I'm happy with those as they are.
I know I've used C pretty poorly as far as factoring out common code between the two input lines - but I'm brushing up my C and will do that.
RA2 and RA3 are the two digital input lines. My algorithm is not dissimilar to how debouncing would be done with a low pass capacitor and resistor followed by a schmitt trigger. This function is called by the ISR every 0.5ms, and the rotary switch produces transitions as short as 5-10ms.
I am curious how to deal with situations where the rotary switch is turned a bit faster than the algorithm can process. Can further information be deduced from the gray encoding, even when a step is missed because of the low pass delay and limited sample rate? I suppose this could be taken as far as using neural networks?!
rotsw.h
#define ROTSW_AVG_SIZE 8
#define ROTSW_MAX 7
#define ROTSW_UPPER 5
#define ROTSW_LOWER 2
#define ROTSW_MIN 0
void rotsw_sample_avg_schmitt_count();
extern volatile int rotsw_count_steps;
rotsw.c
unsigned int rotsw_samples[ROTSW_AVG_SIZE];
unsigned char rotsw_write_idx = 0;
int rotsw_avg_ra2 = 0;
int rotsw_avg_ra3 = 0;
int ra2 = 0;
int ra3 = 0;
volatile int rotsw_count = 0;
void rotsw_sample_avg_schmitt_count()
{
int sample, old_sample, ra2_changed, ra3_changed, count = rotsw_count;
// Sample RA2 and RA3
old_sample = rotsw_samples[rotsw_write_idx];
rotsw_samples[rotsw_write_idx] = sample = PORTA & 0b00001100;
if (++rotsw_write_idx >= ROTSW_AVG_SIZE) rotsw_write_idx = 0;
// Moving average, turning digital sample to "analogue"
if (old_sample & 0x04) rotsw_avg_ra2--;
if (old_sample & 0x08) rotsw_avg_ra3--;
if (sample & 0x04) rotsw_avg_ra2++;
if (sample & 0x08) rotsw_avg_ra3++;
// 3. Do limit for Schmitt trigger
if (rotsw_avg_ra2 < ROTSW_MIN) rotsw_avg_ra2 = ROTSW_MIN;
else if (rotsw_avg_ra2 > ROTSW_MAX) rotsw_avg_ra2 = ROTSW_MAX;
if (rotsw_avg_ra3 < ROTSW_MIN) rotsw_avg_ra3 = ROTSW_MIN;
else if (rotsw_avg_ra3 > ROTSW_MAX) rotsw_avg_ra3 = ROTSW_MAX;
// Do Schmitt trigger
if (rotsw_avg_ra2 > ROTSW_UPPER){
ra2_changed = !ra2;
ra2 = 1;
} else if (rotsw_avg_ra2 < ROTSW_LOWER){
ra2_changed = ra2;
ra2 = 0;
}
if (rotsw_avg_ra3 > ROTSW_UPPER){
ra3_changed = !ra3;
ra3 = 1;
} else if (rotsw_avg_ra3 < ROTSW_LOWER){
ra3_changed = ra3;
ra3 = 0;
}
// Do rotsw state change count.
if (ra2_changed){
if (ra2 == ra3) count++;
else count--;
}
if (ra3_changed){
if(ra2 == ra3) count--;
else count++;
}
rotsw_count = count;
}
performance c
asked 3 mins ago
CL22CL22
228110
$endgroup$
add a comment |
$begingroup$
I would like feedback on the correctness and performance of this code.
My priorities are also are readability, simplicity and self-documenting code - but I'm happy with those as they are.
I know I've used C pretty poorly as far as factoring out common code between the two input lines - but I'm brushing up my C and will do that.
RA2 and RA3 are the two digital input lines. My algorithm is not dissimilar to how debouncing would be done with a low pass capacitor and resistor followed by a schmitt trigger. This function is called by the ISR every 0.5ms, and the rotary switch produces transitions as short as 5-10ms.
I am curious how to deal with situations where the rotary switch is turned a bit faster than the algorithm can process. Can further information be deduced from the gray encoding, even when a step is missed because of the low pass delay and limited sample rate? I suppose this could be taken as far as using neural networks?!
rotsw.h
#define ROTSW_AVG_SIZE 8
#define ROTSW_MAX 7
#define ROTSW_UPPER 5
#define ROTSW_LOWER 2
#define ROTSW_MIN 0
void rotsw_sample_avg_schmitt_count();
extern volatile int rotsw_count_steps;
rotsw.c
unsigned int rotsw_samples[ROTSW_AVG_SIZE];
unsigned char rotsw_write_idx = 0;
int rotsw_avg_ra2 = 0;
int rotsw_avg_ra3 = 0;
int ra2 = 0;
int ra3 = 0;
volatile int rotsw_count = 0;
void rotsw_sample_avg_schmitt_count()
{
int sample, old_sample, ra2_changed, ra3_changed, count = rotsw_count;
// Sample RA2 and RA3
old_sample = rotsw_samples[rotsw_write_idx];
rotsw_samples[rotsw_write_idx] = sample = PORTA & 0b00001100;
if (++rotsw_write_idx >= ROTSW_AVG_SIZE) rotsw_write_idx = 0;
// Moving average, turning digital sample to "analogue"
if (old_sample & 0x04) rotsw_avg_ra2--;
if (old_sample & 0x08) rotsw_avg_ra3--;
if (sample & 0x04) rotsw_avg_ra2++;
if (sample & 0x08) rotsw_avg_ra3++;
// 3. Do limit for Schmitt trigger
if (rotsw_avg_ra2 < ROTSW_MIN) rotsw_avg_ra2 = ROTSW_MIN;
else if (rotsw_avg_ra2 > ROTSW_MAX) rotsw_avg_ra2 = ROTSW_MAX;
if (rotsw_avg_ra3 < ROTSW_MIN) rotsw_avg_ra3 = ROTSW_MIN;
else if (rotsw_avg_ra3 > ROTSW_MAX) rotsw_avg_ra3 = ROTSW_MAX;
// Do Schmitt trigger
if (rotsw_avg_ra2 > ROTSW_UPPER){
ra2_changed = !ra2;
ra2 = 1;
} else if (rotsw_avg_ra2 < ROTSW_LOWER){
ra2_changed = ra2;
ra2 = 0;
}
if (rotsw_avg_ra3 > ROTSW_UPPER){
ra3_changed = !ra3;
ra3 = 1;
} else if (rotsw_avg_ra3 < ROTSW_LOWER){
ra3_changed = ra3;
ra3 = 0;
}
// Do rotsw state change count.
if (ra2_changed){
if (ra2 == ra3) count++;
else count--;
}
if (ra3_changed){
if(ra2 == ra3) count--;
else count++;
}
rotsw_count = count;
}
performance c
asked 3 mins ago
CL22CL22
228110
$endgroup$
add a comment |
$begingroup$
I would like feedback on the correctness and performance of this code.
My priorities are also are readability, simplicity and self-documenting code - but I'm happy with those as they are.
I know I've used C pretty poorly as far as factoring out common code between the two input lines - but I'm brushing up my C and will do that.
RA2 and RA3 are the two digital input lines. My algorithm is not dissimilar to how debouncing would be done with a low pass capacitor and resistor followed by a schmitt trigger. This function is called by the ISR every 0.5ms, and the rotary switch produces transitions as short as 5-10ms.
I am curious how to deal with situations where the rotary switch is turned a bit faster than the algorithm can process. Can further information be deduced from the gray encoding, even when a step is missed because of the low pass delay and limited sample rate? I suppose this could be taken as far as using neural networks?!
rotsw.h
#define ROTSW_AVG_SIZE 8
#define ROTSW_MAX 7
#define ROTSW_UPPER 5
#define ROTSW_LOWER 2
#define ROTSW_MIN 0
void rotsw_sample_avg_schmitt_count();
extern volatile int rotsw_count_steps;
rotsw.c
unsigned int rotsw_samples[ROTSW_AVG_SIZE];
unsigned char rotsw_write_idx = 0;
int rotsw_avg_ra2 = 0;
int rotsw_avg_ra3 = 0;
int ra2 = 0;
int ra3 = 0;
volatile int rotsw_count = 0;
void rotsw_sample_avg_schmitt_count()
{
int sample, old_sample, ra2_changed, ra3_changed, count = rotsw_count;
// Sample RA2 and RA3
old_sample = rotsw_samples[rotsw_write_idx];
rotsw_samples[rotsw_write_idx] = sample = PORTA & 0b00001100;
if (++rotsw_write_idx >= ROTSW_AVG_SIZE) rotsw_write_idx = 0;
// Moving average, turning digital sample to "analogue"
if (old_sample & 0x04) rotsw_avg_ra2--;
if (old_sample & 0x08) rotsw_avg_ra3--;
if (sample & 0x04) rotsw_avg_ra2++;
if (sample & 0x08) rotsw_avg_ra3++;
// 3. Do limit for Schmitt trigger
if (rotsw_avg_ra2 < ROTSW_MIN) rotsw_avg_ra2 = ROTSW_MIN;
else if (rotsw_avg_ra2 > ROTSW_MAX) rotsw_avg_ra2 = ROTSW_MAX;
if (rotsw_avg_ra3 < ROTSW_MIN) rotsw_avg_ra3 = ROTSW_MIN;
else if (rotsw_avg_ra3 > ROTSW_MAX) rotsw_avg_ra3 = ROTSW_MAX;
// Do Schmitt trigger
if (rotsw_avg_ra2 > ROTSW_UPPER){
ra2_changed = !ra2;
ra2 = 1;
} else if (rotsw_avg_ra2 < ROTSW_LOWER){
ra2_changed = ra2;
ra2 = 0;
}
if (rotsw_avg_ra3 > ROTSW_UPPER){
ra3_changed = !ra3;
ra3 = 1;
} else if (rotsw_avg_ra3 < ROTSW_LOWER){
ra3_changed = ra3;
ra3 = 0;
}
// Do rotsw state change count.
if (ra2_changed){
if (ra2 == ra3) count++;
else count--;
}
if (ra3_changed){
if(ra2 == ra3) count--;
else count++;
}
rotsw_count = count;
}
performance c
asked 3 mins ago
CL22CL22
228110
$endgroup$
I would like feedback on the correctness and performance of this code.
My priorities are also are readability, simplicity and self-documenting code - but I'm happy with those as they are.
I know I've used C pretty poorly as far as factoring out common code between the two input lines - but I'm brushing up my C and will do that.
RA2 and RA3 are the two digital input lines. My algorithm is not dissimilar to how debouncing would be done with a low pass capacitor and resistor followed by a schmitt trigger. This function is called by the ISR every 0.5ms, and the rotary switch produces transitions as short as 5-10ms.
I am curious how to deal with situations where the rotary switch is turned a bit faster than the algorithm can process. Can further information be deduced from the gray encoding, even when a step is missed because of the low pass delay and limited sample rate? I suppose this could be taken as far as using neural networks?!
rotsw.h
#define ROTSW_AVG_SIZE 8
#define ROTSW_MAX 7
#define ROTSW_UPPER 5
#define ROTSW_LOWER 2
#define ROTSW_MIN 0
void rotsw_sample_avg_schmitt_count();
extern volatile int rotsw_count_steps;
rotsw.c
unsigned int rotsw_samples[ROTSW_AVG_SIZE];
unsigned char rotsw_write_idx = 0;
int rotsw_avg_ra2 = 0;
int rotsw_avg_ra3 = 0;
int ra2 = 0;
int ra3 = 0;
volatile int rotsw_count = 0;
void rotsw_sample_avg_schmitt_count()
{
int sample, old_sample, ra2_changed, ra3_changed, count = rotsw_count;
// Sample RA2 and RA3
old_sample = rotsw_samples[rotsw_write_idx];
rotsw_samples[rotsw_write_idx] = sample = PORTA & 0b00001100;
if (++rotsw_write_idx >= ROTSW_AVG_SIZE) rotsw_write_idx = 0;
// Moving average, turning digital sample to "analogue"
if (old_sample & 0x04) rotsw_avg_ra2--;
if (old_sample & 0x08) rotsw_avg_ra3--;
if (sample & 0x04) rotsw_avg_ra2++;
if (sample & 0x08) rotsw_avg_ra3++;
// 3. Do limit for Schmitt trigger
if (rotsw_avg_ra2 < ROTSW_MIN) rotsw_avg_ra2 = ROTSW_MIN;
else if (rotsw_avg_ra2 > ROTSW_MAX) rotsw_avg_ra2 = ROTSW_MAX;
if (rotsw_avg_ra3 < ROTSW_MIN) rotsw_avg_ra3 = ROTSW_MIN;
else if (rotsw_avg_ra3 > ROTSW_MAX) rotsw_avg_ra3 = ROTSW_MAX;
// Do Schmitt trigger
if (rotsw_avg_ra2 > ROTSW_UPPER){
ra2_changed = !ra2;
ra2 = 1;
} else if (rotsw_avg_ra2 < ROTSW_LOWER){
ra2_changed = ra2;
ra2 = 0;
}
if (rotsw_avg_ra3 > ROTSW_UPPER){
ra3_changed = !ra3;
ra3 = 1;
} else if (rotsw_avg_ra3 < ROTSW_LOWER){
ra3_changed = ra3;
ra3 = 0;
}
// Do rotsw state change count.
if (ra2_changed){
if (ra2 == ra3) count++;
else count--;
}
if (ra3_changed){
if(ra2 == ra3) count--;
else count++;
}
rotsw_count = count;
}
performance c
performance c
asked 3 mins ago
CL22CL22
228110
asked 3 mins ago
CL22CL22
228110
asked 3 mins ago
CL22CL22
228110
asked 3 mins ago
CL22CL22
228110
asked 3 mins ago
CL22CL22
228110
228110
add a comment |
add a comment |
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