Digital I/O and Timing

Set and Sense Logic Levels

Set/sense logic levels on digital pins SQ1, SQ2, OD1, SEN, IN2, and CCS.

Digital input names accepted by timing / frequency calls:

IN2, SEN, SQR1, OD1, SQR1_READ, OD1_READ, SQ2, SQ3

Digital outputs controlled by set_state:

OD1, CCS, SQR1 (alias SQ1), SQR2 (alias SQ2)

---

set_state : set a digital pin HIGH (5 V) / LOW (0 V)

p.set_state(**kwargs)

parameter	description
**kwargs	SQR1 / SQ1, SQR2 / SQ2, OD1, CCS = True (HIGH / on) or False (LOW / off)

Only pins passed as keyword arguments are changed; others are left untouched.

Set SQ1 to 5 V, OD1 to 0 V

import eyes17.eyes
p = eyes17.eyes.open()
p.set_state(SQR1=True, OD1=False)

Enable CCS (ExpEYES-17 constant current source)

# ExpEYES-17 only: fixed ~1.1 mA (see p.currentSourceValue)
# SEELab3 uses programmable PCS via p.set_pcs() instead — see Voltage Outputs
p.set_state(CCS=True)
print('CCS current ≈', p.currentSourceValue, 'A')
p.set_state(CCS=False)  # turn off

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get_states : get logic levels on digital pins

p.get_states()

Returns	description
dict	{'IN2', 'SQR1', 'OD1', 'SEN', 'SQR1_OUT', 'OD1_OUT', 'CCS'} → True/False

Measure state of IN2

import eyes17.eyes
p = eyes17.eyes.open()
states = p.get_states()
print(f"IN2 is {'HIGH' if states['IN2'] else 'LOW'}")

Example output

{
 'IN2': True,
 'SQR1': False,
 'OD1': False,
 'SEN': True,
 'SQR1_OUT': False,
 'OD1_OUT': False,
 'CCS': False
}

get_state : get logic level on one pin

p.get_state(channel)

Parameter	description
channel	key from get_states(), e.g. 'IN2', 'OD1', 'SEN', 'CCS'
Returns	bool — True / False

p.get_state('SEN')

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Measure Frequencies and Duty Cycle

get_freq : frequency on IN2 / SEN

p.get_freq(channel='IN2', timeout=1.0)

Measures time for 4 rising edges of the input signal.

parameter	description
channel	'IN2' or 'SEN' (see digital input list above)
timeout	seconds; returns 0 if timed out
return	frequency in Hz

p.set_sq1(1000)
# Connect SQ1 → IN2
print(p.get_freq('IN2'))

get_high_freq : high frequency via counter

p.get_high_freq(pin)

Counts edges for 100 ms using a hardware counter. Useful for frequencies above ~100 kHz. Avoid using the oscilloscope at the same time (shared hardware).

print(p.get_high_freq('IN2'))

duty_cycle : duty cycle on a pin

p.duty_cycle(pin, timeout=2.0)

parameter	description
pin	digital input, e.g. 'IN2'
return	duty cycle in % , or -1 on timeout

print(p.duty_cycle('IN2'))

---

Timing Measurements

Times are returned in seconds (unless noted). Returns -1 or None on timeout.

Interval between edges

Function	Meaning
r2rtime(pin1, pin2)	Rising edge on pin1 → rising edge on pin2
f2ftime(pin1, pin2)	Falling → falling
r2ftime(pin1, pin2)	Rising → falling
f2rtime(pin1, pin2)	Falling → rising

Pins may be the same or different ('IN2', 'SEN', …). For multiple cycles on one pin, prefer multi_r2rtime.

# Connect SQ1 → IN2
p.set_sq1(1000)
T = p.r2rtime('IN2', 'IN2')   # period ≈ 0.001 s
print('Period (s) =', T, '  Freq (Hz) =', 1 / T)

multi_r2rtime : several rising edges on one pin

p.multi_r2rtime(pin, edges=1, timeout=1.0)

Time spanning edges cycles. Valid edges: 1, 2, 3, 4, 8, 12, 16, 32, 48.

# Time for 8 cycles → better resolution at high frequency
T = p.multi_r2rtime('IN2', 8)
print('Freq =', 8 / T)

Output-then-measure (set / clear → edge)

Useful for RC timing, light-barrier TOF, etc.

Function	Action
set2rtime(out, inp)	Drive out HIGH, time until rising edge on inp
set2ftime(out, inp)	Drive out HIGH, time until falling edge on inp
clr2rtime(out, inp)	Drive out LOW, time until rising edge on inp
clr2ftime(out, inp)	Drive out LOW, time until falling edge on inp

out must be a digital output: 'OD1', 'CCS', 'SQR1', 'SQR2'.

# Example: charge via OD1, wait for threshold on SEN
t = p.set2rtime('OD1', 'SEN')
print('Charge time (s) =', t)

---

MeasureInterval : general two-edge interval

p.MeasureInterval(channel1, channel2, edge1, edge2, timeout=0.1)

parameter	description
channel1, channel2	digital inputs
edge1, edge2	'rising', 'falling', or 'four rising edges'
return	signed time in seconds (NaN on timeout). Negative if event 2 occurred first

dt = p.MeasureInterval('IN2', 'SEN', 'rising', 'falling')

SinglePinEdges / DoublePinEdges : timestamped edges

Lower-level calls that return arrays of edge timestamps (seconds).

# Up to 4 rising edges on IN2; optionally set OD1 when starting
T = p.SinglePinEdges('IN2', 'rising', 4, timeout=1.0, OD1=True)

# Edges on two pins
T1, T2 = p.DoublePinEdges('IN2', 'SEN', 'rising', 'falling', 2, 2)

edgeType options: 'rising', 'falling', '4xrising', '16xrising'.

MeasureMultipleDigitalEdges is an older two-channel API; prefer DoublePinEdges / SinglePinEdges.

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Hardware edge counter

For continuous high-rate counting on a digital input (shared hardware with get_high_freq — avoid using the oscilloscope at the same time).

Function	Description
startCounter(chan)	Reset and arm the 32-bit counter on chan (e.g. 'IN2')
pauseCounter()	Freeze counting
resumeCounter()	Continue counting
getCounts()	Read the current count

import time
import eyes17.eyes
p = eyes17.eyes.open()

p.set_sq1(10000)          # 10 kHz test signal → connect SQ1 to IN2
p.startCounter('IN2')
time.sleep(1.0)
print(p.getCounts())      # ≈ 10000
p.pauseCounter()
c1 = p.getCounts()
time.sleep(0.5)
print(p.getCounts() == c1)  # True while paused
p.resumeCounter()
time.sleep(0.5)
print(p.getCounts())

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Ultrasonic distance (HC-SR04)

Wiring: SQ2 → TRIG, IN2 ← ECHO, plus 5 V and GND.

Function	Returns
sr04_distance(speed_of_sound=340.)	distance in cm (0 on timeout)
sr04_distance_time(...)	(timestamp, distance_cm)
sr04_time()	raw echo time in seconds

print(p.sr04_distance(), 'cm')

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Servo motor

p.servo(angle, chan='SQR1')

Outputs ~100 Hz PWM on SQ1 for hobby servos (e.g. SG-90). angle is 0–180°.

p.servo(90)   # center

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Multiplexer / stepper (SEELab3 CS1–CS4)

set_multiplexer(value) sets CS1–CS4 to the binary of value (0–15), for chips such as CD74HC4067.

stepper_move(steps, direction, step_delay=0.01), stepper_forward(), stepper_reverse() step a motor wired to CS1–CS4 using a full-step sequence.