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

The PICAXE-28X1 is a versatile microcontroller designed for educational and hobbyist projects. It features 28 pins, including both analog and digital I/O, and is programmable using a simple BASIC-like language. This makes it an excellent choice for beginners and those looking to quickly prototype electronic projects. The PICAXE-28X1 is widely used in robotics, home automation, data logging, and other applications requiring programmable control.

• Robotics and motor control
• Home automation systems
• Data acquisition and logging
• Educational tools for learning microcontroller programming
• Interactive art installations

The PICAXE-28X1 offers a range of features that make it suitable for a variety of projects. Below are its key technical details:

• Microcontroller Core: Based on the Microchip PIC16F886
• Operating Voltage: 4.5V to 5.5V
• Clock Speed: 8 MHz (internal resonator)
• Programming Language: BASIC-like syntax
• I/O Pins:
  • 16 digital I/O pins
  • 4 analog input pins (10-bit resolution)
• EEPROM: 256 bytes
• RAM: 368 bytes
• Flash Memory: 4 KB (for user programs)
• Communication Protocols: Serial (RS232), I2C, SPI
• Power Consumption: Low-power operation with sleep modes
• Package Type: 28-pin DIP (Dual Inline Package)

The PICAXE-28X1 has 28 pins, each with specific functions. Below is the pinout and description:

The PICAXE-28X1 is easy to use and program, making it ideal for beginners. Below are the steps to get started and important considerations:

1. Power Supply: Connect the VDD pin to a 5V power source and the VSS pin to ground.
2. Programming: Use a PICAXE programming cable to connect the Serial In and Serial Out pins to your computer. The PICAXE Editor software is required to write and upload code.
3. I/O Connections:
   • For digital I/O, connect devices (e.g., LEDs, switches) to the C, B, or A pins.
   • For analog inputs, connect sensors to the ADC pins.
4. Pull-Down Resistors: Use pull-down resistors on input pins to prevent floating states.
5. External Components: Add decoupling capacitors (e.g., 0.1 µF) near the power pins to stabilize the power supply.

Below is an example program to blink an LED connected to pin C.0:

' Blink an LED connected to pin C.0
' The LED will turn on for 1 second and off for 1 second in a loop.

main:                ' Start of the main program loop
  high C.0           ' Turn on the LED (set pin C.0 high)
  pause 1000         ' Wait for 1 second (1000 ms)
  low C.0            ' Turn off the LED (set pin C.0 low)
  pause 1000         ' Wait for 1 second
  goto main          ' Repeat the loop

• Programming Cable: Ensure the correct orientation of the programming cable to avoid damaging the microcontroller.
• Power Supply: Use a regulated 5V power supply to prevent overvoltage damage.
• Pin Protection: Avoid exceeding the maximum current rating (25 mA per pin) to prevent damage.
• Decoupling Capacitors: Always use decoupling capacitors to reduce noise and improve stability.

1. Microcontroller Not Responding:

   • Cause: Incorrect wiring or power supply issues.
   • Solution: Double-check all connections, ensure the power supply is within the specified range, and verify the programming cable is connected correctly.

2. Program Not Uploading:

   • Cause: Incorrect COM port or programming cable not detected.
   • Solution: Verify the correct COM port is selected in the PICAXE Editor. Ensure the programming cable drivers are installed.

3. Analog Readings Are Inaccurate:

   • Cause: Noise or improper sensor connections.
   • Solution: Use shielded cables for sensors and add decoupling capacitors near the ADC pins.

4. LED or Device Not Working:

   • Cause: Incorrect pin configuration or insufficient current.
   • Solution: Verify the pin mode (input/output) in the code and ensure the device is within the current limits.

• Q: Can I use the PICAXE-28X1 with an Arduino?

  • A: Yes, the PICAXE-28X1 can communicate with an Arduino via serial, I2C, or SPI protocols.

• Q: What software is required to program the PICAXE-28X1?

  • A: The PICAXE Editor, available for free on the official PICAXE website.

• Q: Can I power the PICAXE-28X1 with batteries?

  • A: Yes, you can use 4 AA batteries (6V) or a 5V regulated power supply.

• Q: How do I reset the microcontroller?

  • A: Disconnect and reconnect the power supply or use a reset button if included in your circuit.

This documentation provides a comprehensive guide to using the PICAXE-28X1 microcontroller effectively. Happy building!