Global Variables

Global variables are updated by the driver and can be read by user application. They should not be written to.

AFE globals

Variable	Unit	Description
fmstr	Hz	Main clock frequency
tres	us	Timing resolution
CAL_fcal	Hz	Calibration source frequency
CAL_resolution	us	Calibration timing resolution
RCAL_freq	Hz	Calibration resistor modulation frequency
RBIASV_res	MOhm	Common-mode feedback resistance (ECG/BIOZ high-current mode)
V_ref	mV	ADC reference output
V_AVDD	mV	Analog supply voltage

BIOZ globals

Variable	Unit	Description
BIOZ_samplingRate	sps	BIOZ sample rate
BIOZ_frequency	Hz	BIOZ modulation frequency
BIOZ_ahpf	Hz	BIOZ analog HPF (before demodulator)
BIOZ_dlpf	Hz	BIOZ digital LPF (after demodulator)
BIOZ_dhpf	Hz	BIOZ digital HPF (after demodulator)
BIOZ_phase	deg	BIOZ demodulation phase offset
BIOZ_gain	V/V	BIOZ gain
BIOZ_cgmag	nA	BIOZ current-generator magnitude
BIOZ_cmres	kOhm	BIOZ common-mode resistance (low-current mode)
BIOZ_test_rnom	kOhm	BIOZ test resistor nominal value
BIOZ_test_rmod	kOhm	BIOZ test resistor modulation value
BIOZ_test_frequency	Hz	BIOZ test resistor modulation frequency

ECG globals

Variable	Unit	Description
ECG_samplingRate	sps	ECG sample rate
ECG_lpf	Hz	ECG low-pass filter
ECG_hpf	Hz	ECG high-pass filter
ECG_latency	ms	ECG signal group delay
ECG_gain	V/V	ECG amplifier gain
ECG_progression	per second	ECG progression rate
RtoR_resolution	ms	R-to-R timing resolution
RtoR_delay	ms	R-to-R detection delay

Data related globals

Variable	Type	Description
ECG_data	RingBuffer<float,128>	ECG samples buffer
BIOZ_data	RingBuffer<float,128>	BIOZ samples buffer
RTOR_data	RingBuffer<float,16>	RR interval samples buffer (ms)
ecg_available	bool	ECG data-ready latch
bioz_available	bool	BIOZ data-ready latch
rtor_available	bool	RRINT data-ready latch
rr_interval	float	Most recent RR interval (ms)
ecg_counter	int	Samples added by last ECG FIFO read
bioz_counter	int	Samples added by last BIOZ FIFO read
rtor_counter	int	Samples added by last RTOR read

Impedance spectroscopy

Variable	Type	Unit	Description
impedance_magnitude[11]	float[11]	Ohm	Fit result magnitude
impedance_phase[11]	float[11]	deg	Fit result phase
impedance_frequency[11]	float[11]	Hz	Frequency bins

Error & Status globals

Group	Variables
Latched event/fault flags (sticky until cleared)	ecg_fast_recovery_occurred, ecg_overflow_occurred, bioz_cgm_occurred, bioz_undervoltage_occurred, bioz_overvoltage_occurred, bioz_overflow_occurred, ecg_lead_off, leads_on_detected, pll_unlocked_occurred, ecg_available, bioz_available, rtor_available
Per-read result flags	valid_data_detected, EOF_detected

Reset behavior:

• Use clearLatchedStatusFlags() when your application has consumed latched events/faults.
• valid_data_detected and EOF_detected are reset/updated inside readECG(), readBIOZ(), readECG_FIFO(), readBIOZ_FIFO().

Pending IRQ flags used by servicePendingInterrupts():

• afe_irq_pending (INT1 or INT2 edge seen)
• afe_irq1_pending
• afe_irq2_pending

STATUS ownership/clearing strategy:

• MAX30001 STATUS bits like DCLOFFINT, BOVER, BUNDR, BCGMON, LONINT, PLLINT are held until STATUS readback (datasheet).
• The driver therefore latches software flags on every STATUS read path before those hardware bits can clear.
• Reading BioZ range tags (BTAG=001/011) can trigger a STATUS read to disambiguate over-vs-under range; this also goes through the same latching path.
• FIFO overflow tags (ETAG/BTAG=111) require FIFO_RST or SYNCH per datasheet, and the driver issues FIFOReset().