Which arduino board to use?

I am currently using an Arduino Uno in my R2-D2 (we were there at the Corporate office in August). I am looking to decrease the form factor. I will be running a very simple script, where I receive a serial command and then need to send out a serial command via another pin set. Below is an example of the script. I need to power with 5 V power, either through a terminal block or pin set (Not USB).

What would be a good, smaller Arduino board that would satisfy these requirements? I will need 4 of them.

const int rxPin = 2; // Define Rx pin

const int txPin = 3; // Define Tx pin

void setup() {

Serial.begin(9600); // Initialize serial communication at 9600 baud

Serial1.begin(9600); // Initialize Serial1 communication at 9600 baud

}

void loop() {

if (Serial.available() > 0) { // Check if data is available to read

char incomingChar = Serial.read(); // Read the incoming byte

// Send the corresponding second command based on the first command received

switch(incomingChar) {

case ‘0’:

Serial1.println(“0xA7,0x00”);

break;

case ‘1’:

Serial1.println(“0xA7,0x01”);

break;

case ‘2’:

Serial1.println(“0xA7,0x02”);

break;

case ‘3’:

Serial1.println(“0xA7,0x03”);

break;

case ‘4’:

Serial1.println(“0xA7,0x04”);

break;

case ‘5’:

Serial1.println(“0xA7,0x05”);

break;

case ‘6’:

Serial1.println(“0xA7,0x06”);

break;

case ‘7’:

Serial1.println(“0xA7,0x07”);

break;

case ‘8’:

Serial1.println(“0xA7,0x08”);

break;

case ‘9’:

Serial1.println(“0xA7,0x09”);

break;

case ‘A’:

Serial1.println(“0xA7,0x0A”);

break;

case ‘B’:

Serial1.println(“0xA7,0x0B”);

break;

case ‘C’:

Serial1.println(“0xA7,0x0C”);

break;

case ‘D’:

Serial1.println(“0xA7,0x0D”);

break;

case ‘E’:

Serial1.println(“0xA7,0x0E”);

break;

case ‘F’:

Serial1.println(“0xA7,0x0F”);

break;

default:

// Do nothing if an invalid command is received

break;

}

// Wait a short delay to avoid sending too rapidly

delay(100);

}

}

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