XN02 - Digital Outputs

X-NODE Digital Outputs is a module that allows you to generate up to 8 digital signals that can be used to control actuators, relay modules, parallel interfaces such as LCD screens, multiplexers, etc., through a configurable digital interface (UART/I2C) that allows you to connect multiple X-NODE Digital Outputs simultaneously, expanding the number of outputs a system can generate from 8 up to 1016.

TABLE OF CONTENTS

1. How does it work?

2. Hardware description

3. Specification

4. Pinout

5. Usage

6. Downloads

   • Schematic

   • Dimensions

I. How does it work?

The X-NODE Digital Outputs module has an integrated hardware controller that allows you to generate logic signals (3.3VDC TTL) without advanced hardware knowledge, as you only need to send a series of commands in ASCII format via the UART serial communication protocol or using the I2C protocol, this makes the X-NODE able to communicate with any system based on a microcontroller, microprocessor, or industrial equipment. The module integrates 8 green LEDs as indicators and a connection port with 8 outputs and GND. The LEDs have a wide viewing angle, a dissipation of 40 mW, a current flow of 20 mA, and can operate in a temperature range from 0 °C to 80 °C. These can be used as general purpose indicators to visualize the status of different devices, alerts, or sequences. The 9 pin terminal block connector allows you to send signals to other components such as relay modules, parallel interfaces like LCD screens, multiplexers, etc.

X-NODE Digital Outputs is compatible with the mikroBUS™ standard from Mikroe® for easy use with a large ecosystem of hardware development kits. It also has JST connectors compatible with the Qwiic® standard from SparkFun® for quick and easy communication between various modules and development boards via the I2C protocol.

II. Hardware Description

1. 9 pin terminal block connector for AWG wires from 26 to 18 gauge.

2. LED indicators

3. JST connectors compatible with Qwiic®

4. Hardware controller

5. UART <> I2C communication ports

6. X-NODE model

7. X-NODE type

8. Standard mikroBUS™ connectors

9. Hardware version: R2

10. Main component in the X-NODE

III. Specifications

IV. Pinout

The following table shows the pinout of the X-NODE Digital Outputs according to the mikroBUS™ standard (shown in the two center columns).

V. Usage

For easy and quick use of the X-NODE, you can use the ASCII commands provided by the integrated hardware controller via UART serial communication or more advanced use via the I2C protocol.

UART Protocol

Configuration

UART communication uses the following configuration:

• Baud rate: 115,200 bps

• Parity: None

• Data bits: 8

• Stop bits: 1

Syntax

The UART protocol allows you to send instructions in plain ASCII text. Each instruction consists of the X-NODE identifier, a command, and a line ending.

Identifier

The ID identifier consists of the X-NODE model, which can be found in point 6 of the Hardware Description section, and is complemented by an index, which can be a letter from A to Z. By default, it is the letter A. To connect more than one module of the same model in a system, you must configure a unique identifier for each module, allowing up to 26 modules of the same model to be connected via the UART protocol.

Command List

Advanced Commands

Line Ending

The X-NODE will only respond to a command when a set of end-of-line characters are sent, each command must end with these characters: <CR+LF>

• CR means carriage return.

• LF means line feed.

The combination of both characters is a common way computers represent a new line, for example, in a word processor to separate paragraphs.

For the X-NODE, the <CR+LF> characters are used to identify when a command has finished being sent. If the identifier matches the node, if the command exists, and if it is immediately followed by the <CR+LF> characters, then the node will send a response.

Depending on your system, you must configure the sending of these characters in different ways.

UART Arduino Framework Example

// This example shows how to control the outputs
// of the X-NODE by implementing a binary counter.

#include "Arduino.h"

// Sends a fixed-length binary sequence
// (most significant bit first) of 8 bits
void printBinary(uint8_t num) {
  for (int i = 0; i < 8; i++) {
    Serial2.print((num >> i) & 0x01);
  }
  // The println function sends the <CR+LF> characters
  Serial2.println();
}

void setup() {
  // Initialize the serial monitor
  Serial.begin(115200);

  // Initialize UART communication on the MikroBUS port
  Serial2.begin(115200, SERIAL_8N1, 9, 10);
}

void loop() {
  // Generate a binary counter with the XN02 LEDs
  for (uint16_t binary_counter = 0; binary_counter < 256; binary_counter++) {

    // Clear the buffer
    if (Serial2.available()) {
      Serial2.read();
    }
    
    // Send the command
    Serial2.print("XN02A+S=");
    printBinary(binary_counter);

    String success = Serial2.readStringUntil('\n');

    // Check if the operation was successful
    if ( !success.startsWith("OK") ) {
      Serial.println( "Error" );
      delay( 1000 );
      return;
    }

    delay(100);
  }

  delay(1000);
}

I2C Protocol

To establish communication, you must know the I2C address of the X-NODE. The factory value consists of the last two digits of the model after "XN". I2C addresses are usually represented in hexadecimal, while the X-NODE model is in decimal, make sure to use the correct number system.

Configuration

• Communication speed: 100 kHz

• Address: 7 bits

Writing

To write to a register of the X-NODE Digital Inputs, the I2C controller must perform the following operations:

1. Send a start condition: The controller generates a logic low (0) on the SDA pin while SCL remains high (1).

2. Send the X-NODE address: The controller sends the 7-bit address.

3. Send the operation type: The controller indicates whether the operation is read (0) or write (1).

4. Wait for an acknowledgment (ACK) signal: The controller waits to receive a logic low (0) as confirmation (Acknowledgment) that a target with the previously sent address exists on the I2C BUS. If no response (1) is received, it means there was a communication error or the address is incorrect.

5. Write n bytes of data: The controller will write in sequences of 8 bits (1 byte) and in order from the most significant bit first (MSB) as many bytes as it wants to write to the register. The target will send an acknowledgment (ACK) signal for each byte correctly written.

6. Send a stop condition: The controller must release the I2C BUS by generating a logic high (1) on the SDA pin while SCL is high (1).

Reading

To read from a register of the X-NODE Digital Inputs, the I2C controller must perform the following operations:

1. Send a start condition: The controller generates a logic low (0) on the SDA pin while SCL remains high (1).

2. Send the X-NODE address: The controller sends the 7-bit address.

3. Send the operation type: The controller indicates whether the operation is read (0) or write (1).

4. Wait for an acknowledgment (ACK) signal: The controller waits to receive a logic low (0) as confirmation (Acknowledgment) that a target with the previously sent address exists on the I2C BUS. If no response (1) is received, it means there was a communication error or the address is incorrect.

5. Read n bytes of data: The target will send sequences of 8 bits (1 byte) and in order from the most significant bit first (MSB) as many bytes as needed. Upon receiving a byte, the controller must generate an acknowledgment (ACK) signal to request 1 more byte, or a not acknowledged (NACK) signal to indicate that the transmission has ended and request the target to release the BUS.

6. Send a stop condition: The controller must release the I2C BUS by generating a logic high (1) on the SDA pin while SCL is high (1).

Register List

Non-volatile Registers (NV)

Non-volatile registers are stored in the device's EEPROM memory, meaning they will retain the values written to them even if the device is powered off.

OUTPUT Register Structure:

I2C Arduino Framework Example

// This example shows how to control the outputs
// of the X-NODE by implementing a binary counter.

#include <Arduino.h>
#include <Wire.h>

void setup() {
  // Initialize the serial monitor
  Serial.begin(115200);

  // Configure the I2C communication pins
  Wire.setPins(12, 13);
  // Initialize I2C communication
  Wire.begin();
}

void loop() {
  // Generate a binary counter with the XN02 LEDs
  for (uint16_t binary_counter = 0; binary_counter < 256; binary_counter++) {

    // Write to the register
    Wire.beginTransmission(0x02);
    // Select the register
    Wire.write(0x01);
    // Write the state of each output
    Wire.write(binary_counter);

    // Check if the operation was successful
    if (Wire.endTransmission() != 0) {
      Serial.println("Error");
      delay(1000);
      return;
    }

    delay(100);
  }

  delay(1000);
}

VI. Downloads