Nuts and Volts - August 2010

■ FIGURE 1. Bike Blinker schematic.

the temperature sensor and a single pushbutton switch while operating the flashing LEDs. I have used this chip for a number of model railroading projects and knew that it had more than enough capability for this endeavor. I also knew that the eight-pin 12F683 was available in a surface-mount package that would go a long way towards meeting one of the objectives — making the unit as small and lightweight as possible.

Construction

Solder the PIC12F683 to the circuit board; sure to align pin 1 properly. To check the wiring, I like to program the chip as soon as it is mounted. Just connect power (three to five volts DC) to the board and plug in a four pin header serial programming) connection. Successful programming will confirm that the chip has been installed correctly.

Using the Serial Output for Testing

■ PHOTO 6.

■ PHOTO 5.

Pin 7 and ground can be connected to a PC’s serial port for testing. The PIC’s pin 7 goes to pin 2 on the PC’s DB9 serial port connector and ground goes to pin 5 on the DB9. On your PC, set Hyper Terminal for 9600 baud, eight bits, one stop bit and, no parity. When power is applied to the completed Bike Blinker, the version number and current Celsius and Fahrenheit temperatures should be displayed (see Figure 2).