I'm testing the AW9523B IO expander with an Arduino Nano. I can't get the device to be recognized.

Using I2C scanner to find all attached I2C devices.

I've connected AW9523B to the correct pins to the SDA/SCL pints of the Arduino, with 5K pullups. INTN is connected to GND.

An EEPROM is also connected on the bus. The EEPROM is recognized on the bus. I swapped the SDA/SCL pins just to make sure, and still AW9523B was not found on bus.

I've tried changing the AD0 and AD1 pins to no avail.

I have a 22uf capacitor on the VCC.

Changing the AD0 pin does change the default state of a connected LED, so I'm fairly confident the chip is not dead.

I've also tried the two example sketches from:


Curious if anyone has gotten their AW9523B to work.

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Updated Working Schematic enter image description here

  • It sounds like you got to many resistors connected maybe where they should not. The chip works fine if installed properly. Post a schematic of how you have it wired, including links to the technical information on the parts you are using. I looked up the part and is is straightforward, Look at the data sheet, Typical Application 1: Drive 16 function LED, including 6 ports feasible for LED backlight your circuit should look like that. Examine that application.
    – Gil
    Jul 28, 2021 at 18:12
  • Tried removing all the resistors other than the I2C pullups, no help. Updated with schematic.
    – EdHayes3
    Jul 28, 2021 at 19:00
  • How did they connect the LED on the data sheet?
    – Gil
    Jul 28, 2021 at 19:24
  • The device can be either open-drain or push-pull, depending on configuration register, and/or the AD1 and AD0 settings. Either way, it shouldn't impact if the device is found on the I2S bus.
    – EdHayes3
    Jul 28, 2021 at 19:42
  • 2
    Connect RSTN to +5V with a 10K pullup resistor.
    – Majenko
    Jul 28, 2021 at 21:15

1 Answer 1


Transcribing and adding to the answer from the comments.

The AW9523B has a reset (RSTN) pin 23 which is internally pulled low by a 100K ohm resistor (i.e., default = reset). @Majenko suggests attaching a pull-up 10K ohm resistor to +5V (i.e., not reset) to enable the chip.

The data sheet schematics and section describing the reset function (pg14) seem to anticipate the RSTN pin being connected to an MCU GPO pin used to dynamically control the reset function.

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