kst_wire.h

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#ifndef KST_WIRE_H
#define KST_WIRE_H
 
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
/* --- registers ------------------------------------------------------------ */

#define KST_REG_COUNT 32u
#define KST_REG_MAX   0x1Fu
 
/* --- bit timing ----------------------------------------------------------- */

#define KST_HALF_CELL_NS 25400u
#define KST_HALF_CELL_CYCLES_150MHZ 3810u
#define KST_SERVO_CELL_NS      51150u
#define KST_SERVO_HALF_CELL_NS 25575u
 
#define KST_FRAME_BITS  27u   
#define KST_REPLY_BITS  11u   
#define KST_SYNC_PULSES 64u

#define KST_FRAME_MAX_HALF_CELLS 127u
#define KST_FRAME_LEVEL_BYTES    16u
 
/* --- line handling, for the driver ---------------------------------------- */

#define KST_RELEASE_NS 50000u
 
/* --- reply windows, from the master's last edge to the first rising edge -- */

#define KST_READ_ACCEPT_MIN_NS 350000u
#define KST_READ_ACCEPT_MAX_NS 600000u
#define KST_READ_WINDOW_NS     1500000u
#define KST_WRITE_ACCEPT_MIN_NS 3300000u
#define KST_WRITE_ACCEPT_MAX_NS 4200000u
#define KST_WRITE_WINDOW_NS     8000000u
 
/* --- decoder -------------------------------------------------------------- */

#define KST_GLITCH_NS 1500u
#define KST_RX_SEARCH_NS 8000u
#define KST_RX_CONFIRM_NS 12800u
#define KST_RX_HALF_CELL_MIN_NS 24300u
#define KST_RX_HALF_CELL_MAX_NS 26900u
#define KST_RX_FINAL_EDGE_MAX_NS 100000u
#define KST_RX_QUIET_AFTER_NS 200000u

#define KST_CAP_MAX_EDGES 48u
 
/* --- frames --------------------------------------------------------------- */

typedef enum {
    KST_FRAME_READ = 0,     
    KST_FRAME_WRITE,        
    KST_FRAME_SYNC,         
} kst_frame_kind_t;

typedef struct {
    uint8_t kind;                           
    uint8_t n_half;                         
    uint8_t level[KST_FRAME_LEVEL_BYTES];   
} kst_frame_t;

bool kst_frame_read(uint8_t reg, kst_frame_t *out);

bool kst_frame_write(uint8_t reg, uint8_t value, kst_frame_t *out);

void kst_frame_sync(kst_frame_t *out);

bool kst_frame_level(const kst_frame_t *frame, unsigned index);

uint32_t kst_frame_duration_ns(const kst_frame_t *frame);
 
/* --- reply capture -------------------------------------------------------- */

typedef struct {
    uint32_t window_ns;                     
    uint8_t  level0;                        
    uint8_t  overflow;                      
    uint8_t  n_edges;                       
    uint32_t edge_ns[KST_CAP_MAX_EDGES];    
} kst_capture_t;

typedef enum {
    KST_EXPECT_READ = 0,    
    KST_EXPECT_WRITE,       
    KST_EXPECT_SYNC,        
} kst_expect_t;

typedef enum {
    KST_RX_OK = 0,       
    KST_RX_NO_REPLY,     
    KST_RX_QUIET,        
    KST_RX_START_LEVEL,  
    KST_RX_LATE,         
    KST_RX_CELL,         
    KST_RX_LENGTH,       
    KST_RX_RATE,         
    KST_RX_FLAGS,        
    KST_RX_FINAL_EDGE,   
    KST_RX_WINDOW,       
    KST_RX_OVERFLOW,     
    KST_RX_CAPTURE,      
} kst_rx_t;

typedef struct {
    uint8_t  result;        
    uint8_t  value;         
    uint8_t  flags;         
    uint8_t  glitches;      
    uint32_t delay_ns;      
    uint32_t half_cell_ns;  
} kst_reply_t;

uint32_t kst_reply_window_ns(kst_expect_t expect);

kst_rx_t kst_reply_decode(const kst_capture_t *cap, kst_expect_t expect,
                          kst_reply_t *out);
 
#ifdef __cplusplus
}
#endif
 
#endif /* KST_WIRE_H */