Hi, I am using an **OAK-4S** and trying to control a relay using GPIO **20 / 21** from a **Script node** in DepthAI. Here is a simplified version of my code: $$ import depthai as dai import time pipeline = dai.Pipeline() script = pipeline.create(dai.node.Script) script.setScript(""" import time import GPIO MX_PIN = 20 GPIO.setup(MX_PIN, GPIO.OUT) val = False node.warn("Script started") while True: val = not val GPIO.write(MX_PIN, val) node.warn(f"GPIO {MX_PIN} = {val}") time.sleep(0.1) """) device = dai.Device() device.startPipeline(pipeline) while True: time.sleep(1) $$ ### What I observe * The Script runs correctly (logs toggle True / False). * GPIO **20 / 21 never toggle physically**. * Measuring **directly on the M8 female connector**, I see: * \~**1.8 V** static on GPIO 20 / 21 * **No change** when the script toggles * Measuring at the **end of a 6 ft M8 cable**, I only see \~**0.04–0.05 V** * The relay never activates. ### Questions 1. Are GPIO **20 / 21 actually routed to the M8 connector on OAK-4S**? 2. Are these GPIOs **output-capable**, or are they input / sync-only? 3. Is the **1.8 V level expected** (and not 3.3 V)? 4. Is it correct that **OAK-4S does not expose general-purpose GPIOs** suitable for driving external hardware? 5. If so, what is the **recommended way** to control a relay or external actuator from OAK-4S? * External MCU (ESP32 / Arduino)? * UART / USB / Ethernet control? * IO expander? I want to confirm whether this is a **hardware limitation** of OAK-4S rather than a software issue. Thanks in advance for clarification.

@"jakaskerl"#p32705 DEvice :Luxonis, Inc. OAK4-S R9, OS: Luxonis OS RVC4 1.21.1 | 0.17.0

@"kohkone"#p32707 Does it work when you set the MUX GPIOs (70 and 124) to 0? Thanks, Jaka

OAK4S: physical pins(GPIO20/21) are not changing level

kohkone

Hi,

I am using an OAK-4S and trying to control a relay using GPIO 20 / 21 from a Script node in DepthAI.

Here is a simplified version of my code:

$$
import depthai as dai
import time

pipeline = dai.Pipeline()

script = pipeline.create(dai.node.Script)
script.setScript("""
import time
import GPIO

MX_PIN = 20
GPIO.setup(MX_PIN, GPIO.OUT)

val = False
node.warn("Script started")

while True:
val = not val
GPIO.write(MX_PIN, val)
node.warn(f"GPIO {MX_PIN} = {val}")
time.sleep(0.1)
""")

device = dai.Device()
device.startPipeline(pipeline)

while True:
time.sleep(1)
$$

What I observe

The Script runs correctly (logs toggle True / False).
GPIO 20 / 21 never toggle physically.
Measuring directly on the M8 female connector, I see:
- ~1.8 V static on GPIO 20 / 21
- No change when the script toggles
Measuring at the end of a 6 ft M8 cable, I only see ~0.04–0.05 V
The relay never activates.

Questions

Are GPIO 20 / 21 actually routed to the M8 connector on OAK-4S?
Are these GPIOs output-capable, or are they input / sync-only?
Is the 1.8 V level expected (and not 3.3 V)?
Is it correct that OAK-4S does not expose general-purpose GPIOs suitable for driving external hardware?
If so, what is the recommended way to control a relay or external actuator from OAK-4S?
- External MCU (ESP32 / Arduino)?
- UART / USB / Ethernet control?
- IO expander?

I want to confirm whether this is a hardware limitation of OAK-4S rather than a software issue.

Thanks in advance for clarification.

jakaskerl

kohkone
It's a FW issue likely because the mux pins were moved around. Can you give me the revision number of the device? Should be on the label (T25..) or via oakctl list

EDIT: should be GPIOs 79 and 124. If you set those to 0, you should mux to I2C line which is used for GPIO20/21.

Thanks,
Jaka

kohkone

jakaskerl DEvice :Luxonis, Inc. OAK4-S R9, OS: Luxonis OS RVC4 1.21.1 | 0.17.0

jakaskerl

kohkone
Does it work when you set the MUX GPIOs (70 and 124) to 0?

Thanks,
Jaka

kohkone

It's not work when i set Pins 79/124 to 0, and i chekc the voltage of my pins 20/21 whtas i set to 1, i get 1.8V. I have change the state of pins on hub

import GPIO

import time

# Pins de contrôle critiques pour libérer 20/21 sur OAK-4S

MUX_79 = 79

MUX_124 = 124

PIN_21 = 21

PIN_20 = 20

# Initialisation : forcer le MUX à 0

GPIO.setup(MUX_79, GPIO.OUT)

GPIO.setup(MUX_124, GPIO.OUT)

GPIO.write(MUX_79, False)

GPIO.write(MUX_124, False)

# Config des pins cibles

GPIO.setup(PIN_21, GPIO.OUT)

GPIO.setup(PIN_20, GPIO.OUT)

if GPIO.read(124) == False and GPIO.read(79) == False :

node.warn("Script ready : MUX lock at 0")

else:

node.warn("Script not ready! : MUX lock at 1")

state = False

while True:

# waiting msg from host

node.io['in'].get()

state = not state

# On réaffirme l'état du MUX et on change les sorties

GPIO.write(MUX_79, False)

GPIO.write(MUX_124, False)

GPIO.write(PIN_21, state)

GPIO.write(PIN_20, state)

node.warn(f"GPIO 20/21 passes a : {state}")