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redo state algorithm

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This commit is contained in:
Dan Halbert 2018-06-01 11:00:40 -04:00 committed by Scott Shawcroft
parent 9920f0a5de
commit f386144428
2 changed files with 54 additions and 30 deletions
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81
ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c
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@ -63,17 +63,14 @@ void common_hal_rotaryio_incrementalencoder_construct(rotaryio_incrementalencode
set_eic_channel_data(self->eic_channel_a, (void*) self);
set_eic_channel_data(self->eic_channel_b, (void*) self);
bool pin_a_level = gpio_get_pin_level(self->pin_a);
bool pin_b_level = gpio_get_pin_level(self->pin_b);
if (!pin_a_level && !pin_b_level) {
self->last_state = 1;
} else if (!pin_a_level && pin_b_level) {
self->last_state = 2;
} else if (pin_a_level && pin_b_level) {
self->last_state = 3;
} else {
self->last_state = 4;
}
self->position = 0;
self->quarter_count = 0;
// Top two bits of self->last_state don't matter, because they'll be gone as soon as
// interrupt handler is called.
self->last_state =
((uint8_t) gpio_get_pin_level(self->pin_a) << 1) |
(uint8_t) gpio_get_pin_level(self->pin_b);
turn_on_eic_channel(self->eic_channel_a, EIC_CONFIG_SENSE0_BOTH_Val, EIC_HANDLER_INCREMENTAL_ENCODER);
turn_on_eic_channel(self->eic_channel_b, EIC_CONFIG_SENSE0_BOTH_Val, EIC_HANDLER_INCREMENTAL_ENCODER);
@ -101,29 +98,55 @@ mp_int_t common_hal_rotaryio_incrementalencoder_get_position(rotaryio_incrementa
void incrementalencoder_interrupt_handler(uint8_t channel) {
rotaryio_incrementalencoder_obj_t* self = get_eic_channel_data(channel);
// This table also works for detent both at 11 and 00
// For 11 at detent:
// Turning cw: 11->01->00->10->11
// Turning ccw: 11->10->00->01->11
// For 00 at detent:
// Turning cw: 00->10->11->10->00
// Turning ccw: 00->01->11->10->00
// index table by state <oldA><oldB><newA><newB>
#define BAD 7
static const int8_t transitions[16] = {
0, // 00 -> 00 no movement
-1, // 00 -> 01 3/4 ccw (11 detent) or 1/4 ccw (00 at detent)
+1, // 00 -> 10 3/4 cw or 1/4 cw
BAD, // 00 -> 11 non-Gray-code transition
+1, // 01 -> 00 2/4 or 4/4 cw
0, // 01 -> 01 no movement
BAD, // 01 -> 10 non-Gray-code transition
-1, // 01 -> 11 4/4 or 2/4 ccw
-1, // 10 -> 00 2/4 or 4/4 ccw
BAD, // 10 -> 01 non-Gray-code transition
0, // 10 -> 10 no movement
+1, // 10 -> 11 4/4 or 2/4 cw
BAD, // 11 -> 00 non-Gray-code transition
+1, // 11 -> 01 1/4 or 3/4 cw
-1, // 11 -> 10 1/4 or 3/4 ccw
0, // 11 -> 11 no movement
};
// Shift the old AB bits to the "old" position, and set the new AB bits.
// TODO(tannewt): If we need more speed then read the pin directly. gpio_get_pin_level has
// smarts to compensate for pin direction we don't need.
bool pin_a = gpio_get_pin_level(self->pin_a);
bool pin_b = gpio_get_pin_level(self->pin_b);
self->last_state = (self->last_state & 0x3) << 2 |
((uint8_t) gpio_get_pin_level(self->pin_a) << 1) |
(uint8_t) gpio_get_pin_level(self->pin_b);
uint8_t this_state;
if (!pin_a && !pin_b) {
this_state = 1;
} else if (!pin_a && pin_b) {
this_state = 2;
} else if (pin_a && pin_b) {
this_state = 3;
} else {
this_state = 4;
int8_t quarter_incr = transitions[self->last_state];
if (quarter_incr == BAD) {
// Missed a transition. We don't know which way we're going, so do nothing.
return;
}
// Handle wrap around explicitly.
if (this_state == 4 && self->last_state == 1) {
self->position -= 1;
} else if (this_state == 1 && self->last_state == 4) {
self->quarter_count += quarter_incr;
if (self->quarter_count >= 4) {
self->position += 1;
} else {
self->position += (this_state - self->last_state);
self->quarter_count = 0;
} else if (self->quarter_count <= -4) {
self->position -= 1;
self->quarter_count = 0;
}
self->last_state = this_state;
}

3
ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.h
View File

@ -37,7 +37,8 @@ typedef struct {
uint8_t pin_b;
uint8_t eic_channel_a:4;
uint8_t eic_channel_b:4;
uint8_t last_state;
uint8_t last_state:4; // <old A><old B><new A><new B>
int8_t quarter_count:4; // count intermediate transitions between detents
mp_int_t position;
} rotaryio_incrementalencoder_obj_t;