Servo - June 2009

How it Works

The description line “*** Main program loop ***” begins this section and it is quickly followed by the “main:” label.

‘ Main program loop

main:

This label defines a location within the program where the main section of code begins. Under this label is where the LED is functioned. The HIGH and LOW command do most of the work. The HIGH command is used to output five volts to the LED. The LOW command is used to output ground or zero volts to the LED. Both commands are followed by the port number connected to the LED. This makes the HIGH and LOW commands act on the P1 LED only.

high 1

‘Set LED0 on

low 1

‘Set LED0 off

Because the HIGH and LOW commands are so quick, a delay between these commands is required to make the LED blink visible. The amount of time the LED is off or on is controlled by the PAUSE command.

The PAUSE command does nothing but delay. The PAUSE command includes a number that determines how many milliseconds (1/1000’s of a second) to delay. In this case, 1,000 is used which represents 1,000 milliseconds or one second.

pause 1000 ‘ Delay for 1 second

Finally, the program goes into a loop so the whole process can be completed over and over again. Using the GOTO command generates the loop. The GOTO command is used to jump program control back to the top of the loop or to the “main” label.

goto main

‘ Loop back and do it again

To make sure the program does not get lost, the END command is added at the bottom. If this command is ever encountered, the program will stop running until the reset switch is pressed or power is removed and reconnected.

Conclusion

The Ultimate OEM Atom Nano module is a great development tool for the beginner. Figure 8 shows it connected to a breadboard so you can easily connect more circuitry to the header pins. There are many options for getting started with microcontrollers but the Atom Nano is one of the best for the true beginner. We’ll use this module in future projects to help you get your feet