Questions tagged [expander]
Questions regarding Port or IO Expanders, be it I2C, SPI, 1-Wire, serial/uart or similar. Shift-Registers are normally NOT considered Expanders, and have their own tag.
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UART GPIO Expanders
I'm looking for a GPIO expander with UART interface, but I can't find a single IC. I know that this is not the place to ask for product recommendations, but I wonder why there are hundreds of GPIO ...
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Issue controlling MOSFET with PCF8575
I'm currently trying to control an array of MOSFETS so I can drive several solenoids. I'm using the Boron from particle.io as my main board, the PCF8575 as my I/O expander, the MAX3004 as a level ...
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Why are GPIO Expander Registers Being Rewritten?
I'm using an LPC1768 microcontroller (mbed) and 4 GPIO expanders (MCP23017). I am trying to write to the expanders to enable the pull up resistors and some other functions, but am getting strange ...
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Does my GPIO Expander have a floating pin? [Button and pull-up resistor]
I am using GPIO expanders (MCP23017) for an array of buttons. Each button is connected between GND and an input pin of the expander. I've enabled the 100k internal pull-up resistor on the MCP23017 (...
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2
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3.3v/5.0v selectable IO port expander
I have designed a basic IO port expander that has uses a bi-directional voltage translator in the hope to have a voltage selectable IO to an external device. Voltages are most likely to be 3.3v / 5.0v....
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Two PCF8574 detected but not the third PCF8574
I'll be using an Arduino Nano 33 IoT together with three PCF8574 IO expander boards. I've managed to connect two PCF8574s together and communicate to each of them individually at different address ...
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Using MAX7301 GPIO Expander for Raspberry Pi Switching and Chip Selecting
I'm designing a PCB that uses Analog Devices' MAX7301AAX GPIO Expander IC to expand the Raspberry PI's GPIOs.
Digikey MAX7301
The reason I'm using this IC is that my application requires a lot of ...
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Issues with I2C from MCP23017on Arduino
I am trying to use the MCP23017 expander chip with a Metro Mini by Adafruit (pinout below) and I can't get the microcontroller to connect reliably via I2C.
update
I connected the RESET pin to 5V and ...
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Confused by i/o expander datasheet note re internal pull-ups
The inputs on the NXP PCAL6524 i/o expander can be configured with internal pull-up or pull-down resistors.
The datasheet states, "External resistors are required for inputs... that may float. If ...
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24V I/O (PLC) to 3.3V interface with opto and PCF8574
I am more of a software guy, and I want to make sure my design works before sending it off to fabrication.
I need to interface with 24V PLC I/Os. I want a simple design for now, as I can add ...
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Should I connect the base of a 5 V high-side PNP to a 3.3 V GPIO IC?
I'm trying to drive a 5V 200mA fan from a PCF8574 powered by 3.3 V. For context, I asked a separate question about using active low vs high on this expander, and @Justme recommended using a high-side ...
- 2,113
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Is active HIGH or LOW preferred for driving loads with the PCF8574?
I'm switching a 5V 200mA case fan with a PCF8574. Since this expander is best used as a current sink (it can sink 25mA, but I think it can only supply something like 300uA), I supposed that a PNP ...
- 2,113
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Is it advisable to current sink an LED sourced from 5V into a PCF8574 sourced from 3V3?
I'm using a PCF8574 to sink current from an LED. The PCF8574 VDD is 3V3, but the LED is sourcing from 5V.
I think voltage drop on the LED is around 2V, so if I understand correctly, then the IO IC ...
- 2,113
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Why does read from I2C GPIO Expander MCP23017 requires NACK
I'm using the MCP23017 16-bit I2C GPIO Expander in combination with the microcontroller PIC18F47J53. Both products are from Microchip.
Datasheet MCP23017
Datasheet PIC18F47J53
I use MCC (MPLab Code ...
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I2C Strange goings on
I am using a Teensy 4.0 and an MCP23016 Port Expander (only I2C device) on my PCB.
I have 4k7 pullups to 3V3 on SDA & SCK.
SCK track is 77.9 mm long, 0.254 wide.
SDA 64.3 mm long, 0.254 wide.
I ...
