system_config Reference #

Global runtime configuration struct holding all Bus Pirate settings, state, and pin assignments.

Overview #

The system_config struct is a single global instance (extern struct _system_config system_config) defined in src/system_config.h. It is initialized by system_init() at startup and read/written throughout the firmware. Most uint32_t fields use that width to standardize JSON parsing for persisted settings.

#include "system_config.h"

// Access anywhere in the firmware:
if (system_config.mode == 0) { /* HiZ */ }

Mode & Protocol State #

Pin Tracking #

Pin 0 is initialized to BP_PIN_VREF and pin 9 to BP_PIN_GROUND. All other pins default to BP_PIN_IO. Use the helper functions rather than writing these fields directly.

Error Handling #

Set system_config.error = true in error paths to signal the command dispatcher. The syntax engine uses this flag to evaluate chained operators (;, ||, &&). See error_handling_reference.md for conventions.

Terminal Settings #

LED & LCD Settings #

The led_effect / led_effect_as_uint32 union allows the LED effect enum to be read/written as a uint32_t for JSON serialization.

Storage #

See storage_guide.md for details on storage initialization and error codes.

Debug Settings #

Configuration & Hardware #

PWM, Frequency & Auxiliary Pins #

The _pwm_config struct holds float period (seconds) and float dutycycle (0.0–1.0).

Binary Mode #

Miscellaneous #

When to Read vs. Write #

• Read freely — system_config.mode, system_config.hiz, pin state, storage status, display format
• Write carefully — system_config.error (set in error paths only), pin_labels/pin_func (in setup_exc/cleanup only, prefer helper functions)
• Never write directly — system_config.mode (changed by the mode selection system), storage_* fields (managed by the storage subsystem)

Helper Functions #

Defined in src/system_config.h and implemented in src/system_config.c:

// Initialize all fields to defaults — call once at startup
void system_init(void);

// Update a header pin's function and label (by absolute pin index)
// Refuses to modify pins reserved for debug UART
void system_pin_update_purpose_and_label(bool enable, uint8_t pin, enum bp_pin_func func, const char* label);

// Update a BIO pin's function and label (by BIO pin index, offset +1 internally)
void system_bio_update_purpose_and_label(bool enable, uint8_t bio_pin, enum bp_pin_func func, const char* label);

// Track pin active state in a function register bitmask (pwm_active, freq_active, aux_active)
void system_set_active(bool active, uint8_t bio_pin, uint8_t* function_register);

Usage example — claiming a pin for PWM:

system_bio_update_purpose_and_label(true, bio_pin, BP_PIN_PWM, "PWM");
system_set_active(true, bio_pin, &system_config.pwm_active);

Usage example — releasing a pin:

system_bio_update_purpose_and_label(false, bio_pin, BP_PIN_IO, NULL);
system_set_active(false, bio_pin, &system_config.pwm_active);

Related Documentation #

• bio_pin_guide.md — Pin claiming and BIO pin abstraction
• error_handling_reference.md — Error flag conventions and command chaining
• storage_guide.md — Storage subsystem and mount error codes
• Source: src/system_config.h, src/system_config.c