System Monitor & Power Supply

Voltage/current monitoring, ADC multiplexer, and PSU control for Bus Pirate hardware.

System Monitor API

Defined in src/system_monitor.h — periodic monitoring of voltages and currents.

bool monitor(void);
void monitor_init(void);
void monitor_reset(void);
void monitor_force_update(void);
FunctionReturnsPurpose
monitor()boolExecute monitor update, return true if performed
monitor_init()voidInitialize system monitor
monitor_reset()voidReset monitor state
monitor_force_update()voidForce immediate monitor update

Voltage & Current Reading 

bool monitor_get_voltage_char(uint8_t pin, uint8_t digit, char* c);
bool monitor_get_voltage_ptr(uint8_t pin, char** c);
bool monitor_get_current_ptr(char** c);
bool monitor_get_current_char(uint8_t digit, char* c);
void monitor_clear_voltage(void);
void monitor_clear_current(void);
bool monitor_voltage_changed(void);
bool monitor_current_changed(void);

Character-level change detection: monitor_voltage_changed() and monitor_current_changed() enable efficient display updates — only redraw when values change.

AMUX — Analog Multiplexer

Defined in src/pirate/amux.h — routes analog signals to the ADC.

void amux_init(void);
bool amux_select_input(uint16_t channel);
bool amux_select_bio(uint8_t bio);
uint32_t amux_read(uint8_t channel);
uint32_t amux_read_present_channel(void);
uint32_t amux_read_bio(uint8_t bio);
uint32_t amux_read_current(void);
void amux_sweep(void);
void adc_busy_wait(bool enable);
FunctionReturnsPurpose
amux_read_bio(bio)uint32_tRead voltage from BIO pin (12-bit ADC)
amux_read_current()uint32_tRead current sense (12-bit ADC)
amux_sweep()voidRead all channels, store in hw_adc_raw[] and hw_adc_voltage[]
amux_select_bio(bio)boolSelect BIO pin for measurement

AMUX Channel Map (BP5 REV10) 

enum adc_mux{
    HW_ADC_MUX_BPIO7,
    HW_ADC_MUX_BPIO6,
    HW_ADC_MUX_BPIO5,
    HW_ADC_MUX_BPIO4,
    HW_ADC_MUX_BPIO3,
    HW_ADC_MUX_BPIO2,
    HW_ADC_MUX_BPIO1,
    HW_ADC_MUX_BPIO0,
    HW_ADC_MUX_VUSB,
    HW_ADC_MUX_CURRENT_DETECT,
    HW_ADC_MUX_VREG_OUT,
    HW_ADC_MUX_VREF_VOUT,
    HW_ADC_MUX_COUNT
};

ADC Averaging 

#define ADC_AVG_TIMES 64

inline uint32_t get_adc_average(uint32_t avgsum) {
    return ((avgsum + (ADC_AVG_TIMES / 2)) / ADC_AVG_TIMES);
}

extern bool reset_adc_average;
  • 64-sample averaging with proper rounding
  • Set reset_adc_average = true to restart averaging after step changes

ADC Voltage Conversion

From src/platform/bpi5-rev10.h:

// Pins with /2 resistor divider (MUX inputs)
#define hw_adc_to_volts_x2(X) ((6600*hw_adc_raw[X])/4096);
// Pins with no divider (current sense)
#define hw_adc_to_volts_x1(X) ((3300*hw_adc_raw[X])/4096);

PSU Control

PSU hardware varies by platform:

PlatformPSU TypeControl
BP5, BP5XL, BP6BP_HW_PSU_PWMPWM-based voltage regulation
BP7BP_HW_PSU_DACDAC-based voltage regulation

PSU API (from src/pirate/psu.h):

  • PSU enable/disable
  • Voltage setting
  • Current limiting
  • Over-current protection