Microcontroller Circuit Board & Complete Robot Electronics

This page shows the construction of a custom circuit board for the AVR microcontroller and radio electronics shown previously, and the operation of all completed robot electronics together. Here is a photo of the microcontroller on the breadboard:

Here is the proposed layout of the new circuit board:

Here is the completed circuit board with the ATMega16 chip installed:

Actually, this design is larger and more complicated than it needs to be, in that:

• I am using DIP and through-hole components rather than surface mount.
  
  
• I am using an external clock chip rather than the onboard oscillator.
  
  
• The board includes components for the radio, buttons, and 'heartbeat' LEDs.
  
  
• Although the current design uses only part of I/O port B (ISP programmer), port C (LEDs, direction, feedback), and port D (radio, interrupts, PWM), I have brought all other port pins out to headers. This makes the board a bit more generic, and allows for future data acquisition (ADC input on port A) and other applications.

Here is a photo of everything hooked up and running on batteries:

The components include:

• The Bluetooth radio.
  
  
• The AVR microcontroller circuit board.
  
  
• Buttons for reset and 2 interrupts.
  
  
• 9V battery for radio and AVR.
  
  
• The motor controller circuit board.
  
  
• Two DC motors.
  
  
• Two optical switch feedback sensors.
  
  
• 12V batteries for motors.

Here is a very small (24 Mb!) movie of everything running (1:15). Click to download and play (this may take a while).

The movie shows:

1. The AVR running the default program, which just blinks the left LEDs on the right board. The top LED shows that there is 5V power.
   
   
2. After about 18 sec, the right LED comes on, indicating that the radio has received a connection from the Mac.
   
   
3. Then the top motor starts at 1/2 speed. Then the bottom motor starts at 1/2 speed. Then the top motor goes to full speed. Then the top motor stops, and goes at 1/2 speed in reverse, and then full speed. Then the bottom motor stops, and goes into reverse at full speed.

The next step is to build a housing for the circuit boards, and a chassis, wheels, and drivetrain for the robot. Although this system is designed to run a 2 motor differential drive rover, it can be the basis of any generic radio controlled 2 motor (or other PWM actuated device), 2 sensor robotic system.

İSky Coyote 2007