GPIO Control

The I2S0 connector pins come up as general-purpose GPIOs by default — no overlay or jetson-io step is needed. At idle the SoC drives none of them: the four output-capable pins sit hi-z, held HIGH by 604Ω pull-ups on the carrier, and DIN is a floating input. A pin wired to a relay or actuator never transitions at boot.

I2S0 Connector Pin Mapping

ARK Pin	Signal	40-Pin Header	libgpiod Name	Idle at Boot
1	VDD_5V_JPERIPH	-	-	-
2	I2S0_DOUT_3V3	Pin 40	PI.00	HIGH (pulled)
3	I2S0_DIN_3V3	Pin 38	PI.01	hi-z (input)
4	I2S0_LRCLK_3V3	Pin 35	PI.02	HIGH (pulled)
5	I2S0_SCLK_3V3	Pin 12	PH.07	HIGH (pulled)
6	AUD_MCLK_3V3	Pin 7	PAC.06	HIGH (pulled)
7	GND	-	-	-

Confirm the lines are exposed:

sudo gpioinfo | grep -E '"P(H\.07|I\.0[0-2]|AC\.06)"'

Using the GPIOs

Drive and read the lines with libgpiod (gpioset / gpioget) or the Jetson.GPIO Python library. Jetson.GPIO addresses pins by their 40-pin header number and needs version 2.1.12 or newer:

sudo pip3 install 'Jetson.GPIO>=2.1.12'

The example below jumpers HDR40 pin 40 (DOUT) to pin 38 (DIN) and toggles HIGH/LOW, reading each transition back as a loopback test:

import time
import Jetson.GPIO as GPIO

GPIO.setmode(GPIO.BOARD)
GPIO.setup(40, GPIO.OUT, initial=GPIO.LOW)  # I2S0_DOUT
GPIO.setup(38, GPIO.IN)                     # I2S0_DIN

try:
    for level in (GPIO.HIGH, GPIO.LOW, GPIO.HIGH, GPIO.LOW):
        GPIO.output(40, level)
        time.sleep(0.2)
        got = GPIO.input(38)
        print(f"wrote {level} read {got} {'PASS' if got == level else 'FAIL'}")
finally:
    GPIO.cleanup()

ARK-OS ships a complete version of this loopback as i2s_gpio_example.py (on PATH).

GPIO state after your app exits

While your app owns a line, the kernel guarantees its value. On release (clean exit, crash, or kill), the pin retains its last-written value until the next reboot re-asserts the pulled-HIGH idle state. If a line must be safe-off for an active-high load, add an external pull-down or keep a process owning the line (gpioset --mode=signal).

For the full pin reference, electrical details, and safe-state patterns, see the ARK Jetson Kernel GPIO docs.