I2C — ELECROW - FORUM

ESP32 5" HMI i2c port with touch

S1m0n3 — Fri, 06 Jun 2025 11:05:44 +0000

I was trying to use the board in the title to make an interface for a heating device.
Basically, i have to measure an analog temperature sensor, control a few relays and read the time from an RTC module.
My idea was to use i2c based modules to do so under Arduino, specifically:

DS3231 Adafruit RTC module
ADS1115 Adafruit 16bit ADC
2x MCP23017 Adafruit GPIO modules

What i realized is that while all these use the Wire.h library, when using LovyanGFX a different i2c library is internally used to drive the GT911 capacitive touch driver ic breaking the Wire.h functionality.

Is there a way to either use Wire.h for LovyanGFX or disable the touch functionality for a "brief" time freeing up the i2c bus or do I have to rewrite every module library to use the same library LovyanGFX uses?
Thanks in advance.

I2C Issues - CrowPanel x" -HMI ESP32 Display

Bernhard — Tue, 01 Apr 2025 22:48:33 +0000

I need to use one or more PCF8575s with my HMI displays (7, 5, and 2.8 inches) but I cannot get my PCF8575 IO Expander Module I2C to 16IO to work for the life of me. I read all 8575 related posts here but none of the methods has worked for me. First, what library do you recommend, second, is there sample code I can look at for that library? I am using Arduino IDE. Thanks!

I2C and Touch

harryskalvi — Mon, 31 Mar 2025 05:52:04 +0000

Touch Freezes when I2C device is configured

CrowPanel 5in / 7in add I2C communication device with I2C IO expander.

mfujita — Tue, 10 Dec 2024 14:27:35 +0000

I wrote this for my reminder. CrowPanel 5 and 7in use (SDA 19, SLC 20) for TFT operation. Just connect I2C device to I2C(19,20) port does not allow to communicate. I was suffering for a while about this problem connecting to PCF8574 8ch I2C relay board. I found following 2 ways to solve problem.
1. Assign GPIO port for additional I2C device.
Add "Wire.begin(43,44);" in setup( ) and just connect I2C device to GPIO(43,44) port. However if you are using this GPIO port, you need to find another GPIOs.

Include I2C IO expander library.
You can find the I2C IO expander library for most of the I2C devices. This may be specific for each device. For my I2C relay, PCF8574.h is the expander library. I added following in *.ino file. Do not need to write "Wire.begin(19, 20);" in setup( ).

include

PCF8574 PCF2(0x27, &Wire1); //0x27 is the target relay board i2c Address
This allowed to run TFT screen and the Relay in same I2C (19, 20) bas together. You can use GPIO port for other usage. It is also good idea to update the "deviceAddress" in the PCF8574.h file to your device address.

ESP8288 IOT Board & I2C Ports

davidwoolterton — Thu, 18 Jul 2024 16:10:16 +0000

I have just purchased an ESP8266 IOT Board Version 1.0 and I would like to connect a crowtail BME280 Sensor to it. This is an I2C device, but I am having trouble woring out which ports are the default I2C Ports on the ESP8266. Could somebody please help and let me know.
Thanks for any help in advance.