The I2CUI3 is a user interface module for managing IoT devices.

The I2CUI3 can be used as a control panel and status indications in any user devices:

• electronic watches;
• radiation dosimeters;
• smart outlets;
• thermostats;
• multimedia and audio devices;
• weather stations and others.

Digital user interface module compatible with controllers:

• ARDUINO,
• ESP12.OLED_V1,
• NodeMCU board (based on ESP8266-12),
• modules on the ESP8266EX chip,
• ESP32,
• or others, with supply voltage from 2.7 to 5.5 V with 3.3V logic levels.

The I2CUI3 module for MCU-based projects and products provides:

• 2 I2C-bus ports (ingoing and outgoing);
• 5-button joystick style keyboard;
• RGB LED indicator;
• embedded active buzzer;
• keypress Interrupt loopback output;
• setting one of the 4 addresses on the I2C bus by a jumper;
• width: 4 cm., height: 1.4 cm., length: 4 cm.

Functions:

• Input data with a five-button keyboard (left, right, down, up, OK);
• State data output via RGB LED;
• Direct GPIO output of sound signals through buzzer;
• I2C ingoing and outgoing ports for bus topology connection to MCU and external devices.

The use of I2C saves the GPIO of the controller and provides user data input/output in an efficient callback-style and event-driven way.

The following ports are provided on the board:

• SDA - I2C data line;
• SCL - I2C synchronization line;
• 3V3 - power supply from the controller with a voltage in the range from 2.7 to 5.5 V;
• GND "common" from the controller;
• INT - interrupt from the module to the controller’s GPIO;
• Buzzer - buzzer control line from controller’s GPIO;
• Jumper J1 to set the I2C address.

PCB holes for soldering connectors have a step of 2.54 mm for mounting connectors with such a step. We recommend using 4-pin connectors type JST-XH2,5 or DuPont 2.54 4 x 1P pin headers.

Information for programmers

The digital communication interface with the I2C controller is implemented on the 8-bit PCA9538 chip. The module address on the I2C bus - 0x70 (default).

Distribution of I2CUI3 extender ports:

• io0 = LED R;
• io1 = LED B;
• io2 = LED G;
• io3 = UP;
• io4 = RIGHT;
• io5 = OK;
• io6 = DOWN;
• io7 = LEFT

The logic level of all inactive input and output ports is high. Pressing any button switches the ports to (Active-low). The INT output signal provides interrupt handling of buttons. Activation of LED RGB is carried out by a low level (Active-low).

I2C Address Selection

By default, when there is no jumper and/or pin header is not soldered, the default I2C slave device address is 0x73 (A1=1; A0=1 => 1110011). If one needs to select another device's I2C address, then there is a need to solder 3P 2.54 DuPont pin header and set the address with a jumper. Jumper positions may be as follows:

An active buzzer is installed on the board. Active-low on GPIO directly from the controller activates buzzer. The current consumption of the I2CUI3 module at rest is about 1 microampere. In the case of simultaneous data output to R + G + B + buzzer, the maximum current consumption can reach 20 milliamperes.

Contents of delivery

• I2CUI3 module;
• pin headers for soldering.