File syn_encoder.c¶

FileList > input > syn_encoder.c

Quadrature rotary encoder implementation. More...

#include "../drivers/syn_gpio.h"
#include "../util/syn_assert.h"
#include "syn_encoder.h"
#include <string.h>

Public Static Attributes¶

Type	Name
const int8_t	quad_table = `/* multi line expression /` Quadrature state transition table.*

Public Functions¶

Type	Name
int32_t	syn_encoder_get_delta (SYN_Encoder * enc) Get accumulated delta since last call and reset it.
void	syn_encoder_init (SYN_Encoder * enc, SYN_GPIO_Pin pin_a, SYN_GPIO_Pin pin_b) Initialize encoder.
void	syn_encoder_set_stats (SYN_Encoder * enc, SYN_Signal * stats) Attach a signal statistics window for velocity tracking.
void	syn_encoder_set_steps_per_detent (SYN_Encoder * enc, uint8_t spd) Set steps-per-detent (default = 1).
void	syn_encoder_update (SYN_Encoder * enc) Sample pins and update position.

Detailed Description¶

Uses a 2-bit state machine with a lookup table for direction decoding. Handles all four quadrature transitions correctly with no missed steps.

Public Static Attributes Documentation¶

variable quad_table¶

Quadrature state transition table.

const int8_t quad_table[16];

16 entries: (old_state << 2) | new_state. Index = (old_A<<3 | old_B<<2 | new_A<<1 | new_B). Value: +1 for clockwise, -1 for counter-clockwise, 0 for invalid/no-change.

Public Functions Documentation¶

function syn_encoder_get_delta¶

Get accumulated delta since last call and reset it.

int32_t syn_encoder_get_delta (
    SYN_Encoder * enc
)

Parameters:

enc Encoder instance.

Returns:

Number of steps (positive = CW, negative = CCW).

function syn_encoder_init¶

Initialize encoder.

void syn_encoder_init (
    SYN_Encoder * enc,
    SYN_GPIO_Pin pin_a,
    SYN_GPIO_Pin pin_b
)

Parameters:

enc Encoder instance.
pin_a Channel A GPIO.
pin_b Channel B GPIO.

function syn_encoder_set_stats¶

Attach a signal statistics window for velocity tracking.

void syn_encoder_set_stats (
    SYN_Encoder * enc,
    SYN_Signal * stats
)

Each call to syn_encoder_get_delta() pushes the delta value into the signal window, giving you velocity min/max/mean/variance.

Parameters:

enc Encoder.
stats Initialized SYN_Signal, or NULL to detach.

function syn_encoder_set_steps_per_detent¶

Set steps-per-detent (default = 1).

void syn_encoder_set_steps_per_detent (
    SYN_Encoder * enc,
    uint8_t spd
)

Many mechanical encoders generate 2 or 4 state changes per physical detent. Setting this to 4 means position and delta only increment once per detent rather than once per state change.

Parameters:

enc Encoder instance.
spd Steps per detent (1, 2, or 4).

function syn_encoder_update¶

Sample pins and update position.

void syn_encoder_update (
    SYN_Encoder * enc
)

Call from a timer ISR or fast polling loop. Must be called at ≥4× the encoder's maximum rotation speed.

Parameters:

enc Encoder instance.

The documentation for this class was generated from the following file src/syntropic/input/syn_encoder.c