Data Structures

Reference for the main data structures used in NanoVNA-H firmware.

Measurement Data

measured Array

The primary measurement storage array:

extern float measured[2][SWEEP_POINTS_MAX][2];

Dimension	Index	Meaning
First [2]	0	S11 (reflection) data
	1	S21 (transmission) data
Second [SWEEP_POINTS_MAX]	0..points-1	Sweep point index
Third [2]	0	Real part
	1	Imaginary part

Example access:

// Get S11 at sweep point 50
float s11_re = measured[0][50][0];
float s11_im = measured[0][50][1];

// Get S21 at sweep point 50
float s21_re = measured[1][50][0];
float s21_im = measured[1][50][1];

Size by target:

Target	SWEEP_POINTS_MAX	Array Size
F072	101	1,616 bytes
F303	401	6,416 bytes

---

properties_t Structure

Stores calibration data and sweep settings. Saved to flash in slots 0-4 (F072) or 0-6 (F303).

typedef struct properties {
  uint32_t magic;                    // PROPERTIES_MAGIC (0x434f4e54)
  freq_t   _frequency0;              // Sweep start frequency
  freq_t   _frequency1;              // Sweep stop frequency
  freq_t   _cal_frequency0;          // Calibration start frequency
  freq_t   _cal_frequency1;          // Calibration stop frequency
  freq_t   _var_freq;                // Frequency step (0 = auto)
  uint16_t _mode;                    // Time domain flags, display mode
  uint16_t _sweep_points;            // Points in measurement sweep
  int8_t   _current_trace;           // Active trace (0-3, -1 disabled)
  int8_t   _active_marker;           // Active marker (0-7, -1 disabled)
  int8_t   _previous_marker;         // Previous marker for delta
  uint8_t  _power;                   // Output power (0-3)
  uint8_t  _cal_power;               // Power used during calibration
  uint8_t  _measure;                 // Measure module mode
  uint16_t _cal_sweep_points;        // Points used in calibration
  uint16_t _cal_status;              // Calibration status flags
  trace_t  _trace[TRACES_MAX];       // Trace configurations (4)
  marker_t _markers[MARKERS_MAX];    // Marker configurations (8)
  uint8_t  _reserved;
  uint8_t  _velocity_factor;         // Cable velocity (0-100%)
  float    _electrical_delay[2];     // E-delay for S11, S21 (seconds)
  float    _var_delay;               // E-delay step for lever
  float    _s21_offset;              // S21 offset in dB
  float    _portz;                   // Port Z renormalization
  float    _cal_load_r;              // Calibration LOAD R value
  uint32_t _reserved1[7];
  float    _cal_data[CAL_TYPE_COUNT][SWEEP_POINTS_MAX][2];
  uint32_t checksum;
} properties_t;

Calibration Data

float _cal_data[CAL_TYPE_COUNT][SWEEP_POINTS_MAX][2];

Index	CAL_TYPE	Description
0	CAL_LOAD	Load standard measurement
1	CAL_OPEN	Open standard measurement
2	CAL_SHORT	Short standard measurement
3	CAL_THRU	Through standard measurement
4	CAL_ISOLN	Isolation measurement

Calibration Status Flags

#define CALSTAT_LOAD   (1<<0)  // Load data collected
#define CALSTAT_OPEN   (1<<1)  // Open data collected
#define CALSTAT_SHORT  (1<<2)  // Short data collected
#define CALSTAT_THRU   (1<<3)  // Through data collected
#define CALSTAT_ISOLN  (1<<4)  // Isolation data collected
#define CALSTAT_ES     (1<<5)  // Source match error term
#define CALSTAT_ER     (1<<6)  // Reflection tracking error term
#define CALSTAT_ET     (1<<7)  // Transmission tracking error term
#define CALSTAT_APPLY  (1<<8)  // Calibration is being applied
#define CALSTAT_INTERPOLATED     (1<<9)   // Data is interpolated
#define CALSTAT_ENHANCED_RESPONSE (1<<10) // Enhanced response cal

Mode Flags

#define DOMAIN_MODE             (1<<0)  // 0=freq, 1=time
#define TD_FUNC                 (0b11<<1)
#define TD_FUNC_BANDPASS        (0b00<<1)
#define TD_FUNC_LOWPASS_IMPULSE (0b01<<1)
#define TD_FUNC_LOWPASS_STEP    (0b10<<1)
#define TD_WINDOW               (0b11<<3)
#define TD_WINDOW_NORMAL        (0b00<<3)
#define TD_WINDOW_MINIMUM       (0b01<<3)
#define TD_WINDOW_MAXIMUM       (0b10<<3)
#define TD_CENTER_SPAN          (1<<6)  // Center/span vs start/stop
#define TD_MARKER_TRACK         (1<<7)  // Marker tracking enabled
#define TD_MARKER_DELTA         (1<<8)  // Delta marker mode

---

config_t Structure

Device configuration stored separately from calibration. Survives calibration recall.

typedef struct config {
  uint32_t magic;                    // CONFIG_MAGIC (0x434f4e56)
  uint32_t _harmonic_freq_threshold; // Harmonic mode threshold
  int32_t  _IF_freq;                 // IF frequency offset
  int16_t  _touch_cal[4];            // Touch calibration corners
  uint16_t _vna_mode;                // VNA mode flags
  uint16_t _dac_value;               // DAC output value
  uint16_t _vbat_offset;             // Battery voltage offset
  uint16_t _bandwidth;               // Default bandwidth
  uint8_t  _lever_mode;              // Lever control mode
  uint8_t  _brightness;              // LCD brightness (F303)
  uint16_t _lcd_palette[MAX_PALETTE]; // Color palette (32 colors)
  uint32_t _serial_speed;            // USART baud rate
  uint32_t _xtal_freq;               // TCXO reference frequency
  float    _measure_r;               // Reference impedance
  uint8_t  _band_mode;               // Band selection mode
  uint8_t  _reserved[3];
  uint32_t checksum;
} config_t;

VNA Mode Flags

enum {
  VNA_MODE_AUTO_NAME = 0,    // Auto-generate filenames
  VNA_MODE_SMOOTH,           // Smooth function type
  VNA_MODE_CONNECTION,       // USB or serial console
  VNA_MODE_SEARCH,           // Marker search (max/min)
  VNA_MODE_SHOW_GRID,        // Show grid values
  VNA_MODE_DOT_GRID,         // Dotted grid lines
  VNA_MODE_BACKUP,           // Save settings on power-off
  VNA_MODE_FLIP_DISPLAY,     // 180-degree flip
  VNA_MODE_SEPARATOR,        // Decimal separator (./,)
  VNA_MODE_TIFF,             // Screenshot format
  VNA_MODE_USB_UID           // Use unique USB serial
};

---

trace_t Structure

Configuration for each display trace.

typedef struct trace {
  uint8_t enabled;       // 0=off, 1=on
  uint8_t type;          // Trace type (0-29)
  uint8_t channel;       // Data channel (0=S11, 1=S21)
  uint8_t smith_format;  // Smith marker format (0-12)
  float scale;           // Scale per division
  float refpos;          // Reference position (0-8)
} trace_t;

Trace types: See Trace Types for complete list.

Constants:

#define TRACES_MAX       4   // Display traces
#define STORED_TRACES    1   // Memory traces
#define TRACE_INVALID   -1   // No active trace

---

marker_t Structure

Configuration for each marker.

typedef struct marker {
  uint8_t  enabled;     // 0=off, 1=on
  uint8_t  reserved;
  uint16_t index;       // Sweep point index
  freq_t   frequency;   // Frequency in Hz
} marker_t;

Constants:

#define MARKERS_MAX      8   // Maximum markers
#define MARKER_INVALID  -1   // No active marker

---

trace_info_t Structure

Display information for each trace type.

typedef struct trace_info {
  const char *name;            // Display name
  const char *format;          // Printf format for value
  const char *dformat;         // Printf format for delta
  const char *symbol;          // Unit symbol
  float refpos;                // Default reference position
  float scale_unit;            // Default scale per division
  get_value_cb_t get_value_cb; // Value calculation callback
} trace_info_t;

Used in: trace_info_list[MAX_TRACE_TYPE] (30 entries)

---

marker_info_t Structure

Display information for Smith chart marker formats.

typedef struct marker_info {
  const char *name;            // Format name
  const char *format;          // Printf format
  get_value_cb_t get_re_cb;    // Real value callback
  get_value_cb_t get_im_cb;    // Imaginary value callback
} marker_info_t;

Used in: marker_info_list[MS_END] (13 entries)

---

Frequency Type

typedef uint32_t freq_t;

All frequencies stored in Hz as unsigned 32-bit integers.

Value	Frequency
50000	50 kHz
1000000	1 MHz
100000000	100 MHz
1500000000	1.5 GHz

---

Audio Sample Type

typedef int16_t audio_sample_t;

16-bit signed samples from the TLV320AIC3204 codec.

Buffer size:

#define AUDIO_SAMPLES_COUNT   48     // Samples per measurement
#define AUDIO_BUFFER_LEN      96     // Left + right channels

---

Global Variables

Current State

extern config_t config;           // Device configuration
extern properties_t current_props; // Current calibration/settings
extern float measured[2][SWEEP_POINTS_MAX][2]; // Measurement data
extern uint8_t sweep_mode;        // Sweep state flags
extern uint16_t lastsaveid;       // Last saved slot

Convenience Macros

#define frequency0       current_props._frequency0
#define frequency1       current_props._frequency1
#define sweep_points     current_props._sweep_points
#define cal_status       current_props._cal_status
#define cal_data         current_props._cal_data
#define trace            current_props._trace
#define markers          current_props._markers
#define active_marker    current_props._active_marker
#define current_trace    current_props._current_trace

---

Memory Layout Summary

F072

Structure	Size
properties_t	~6 KB
config_t	~100 bytes
measured[]	1,616 bytes
spi_buffer[]	4 KB

RAM available: 16 KB

F303

Structure	Size
properties_t	~24 KB
config_t	~100 bytes
measured[]	6,416 bytes
spi_buffer[]	4 KB

RAM available: 40 KB

Note

The properties_t structure size is dominated by _cal_data, which stores calibration measurements for all sweep points.