How to Use PICAXE-28X1: Examples, Pinouts, and Specs

The PICAXE-28X1, manufactured by Revolution Education Ltd, is a versatile microcontroller designed for educational and hobbyist projects. It features 28 pins, providing ample input and output connections for a wide range of applications. The PICAXE-28X1 is programmable using a simple BASIC-like language, making it accessible to beginners while still offering advanced functionality for experienced users.

• Robotics: Controlling motors, servos, and sensors
• Home automation: Managing lighting, temperature, and security systems
• Data logging: Collecting and storing sensor data
• Educational projects: Teaching programming and electronics concepts
• Prototyping: Rapid development of electronic circuits and systems

The following table outlines the key technical details of the PICAXE-28X1 microcontroller:

The PICAXE-28X1 has a 28-pin dual in-line package (DIP). The pin configuration is as follows:

1. Power Supply: Connect the V+ pin to a 5V power source and the GND pin to ground.
2. Programming: Use the PICAXE Programming Editor software to write and upload code via the Serial In and Serial Out pins.
3. Input/Output: Connect sensors, LEDs, or other devices to the I/O pins. Configure the pins as input or output in the code.
4. Communication: Use the I2C/SPI pins for interfacing with other devices like displays or additional sensors.

• Decoupling Capacitor: Place a 0.1 µF capacitor between V+ and GND to stabilize the power supply.
• Pull-Down Resistors: Use pull-down resistors on input pins to prevent floating states.
• Programming Cable: Use the official PICAXE USB programming cable for reliable communication.
• Pin Protection: Avoid exceeding the voltage and current limits of the pins to prevent damage.

Although the PICAXE-28X1 is a standalone microcontroller, it can communicate with an Arduino UNO via serial communication. Below is an example of how to send data from the PICAXE-28X1 to an Arduino UNO:

PICAXE-28X1 Code:

' Send data to Arduino via serial communication
main:
  serout C.0, N2400, ("Hello Arduino!") ' Send "Hello Arduino!" at 2400 baud
  pause 1000                            ' Wait 1 second
  goto main                             ' Repeat the process

Arduino UNO Code:

void setup() {
  Serial.begin(2400); // Initialize serial communication at 2400 baud
}

void loop() {
  if (Serial.available() > 0) {
    String data = Serial.readString(); // Read incoming data
    Serial.println(data);              // Print the received data to the Serial Monitor
  }
}

1. The microcontroller does not respond to programming commands.

   • Ensure the power supply is stable and within the operating voltage range (4.5V to 5.5V).
   • Verify the programming cable connections to the Serial In and Serial Out pins.
   • Check that the correct COM port is selected in the PICAXE Programming Editor.

2. The program runs erratically or not at all.

   • Confirm that the code is free of syntax errors.
   • Use a decoupling capacitor to reduce noise in the power supply.
   • Ensure that input pins are not left floating by using pull-down resistors.

3. I/O pins are not functioning as expected.

   • Verify that the pins are correctly configured as input or output in the code.
   • Check for short circuits or incorrect wiring in the circuit.

Q: Can the PICAXE-28X1 be powered by batteries?
A: Yes, the PICAXE-28X1 can be powered by 4 AA batteries (6V) or a 5V regulated power supply.

Q: What is the maximum current that an I/O pin can handle?
A: Each I/O pin can source or sink up to 20 mA, with a total maximum current of 90 mA for all pins combined.

Q: Can I use the PICAXE-28X1 with a breadboard?
A: Yes, the 28-pin DIP package is breadboard-friendly, making it easy to prototype circuits.

Q: Is the PICAXE-28X1 compatible with external EEPROMs?
A: Yes, the PICAXE-28X1 supports I2C communication, allowing it to interface with external EEPROMs and other I2C devices.