Tuesday, March 10, 2009

REA Technologies, Inc. builds Baseball Pitch Speed Interface Board

Back in the early part of 2004, our local minor league baseball team, the Hickory Crawdads, replaced their score board with the modern LED score board. The old Light Bulb Score Board had an area that displayed the Baseball Pitch Speed in miles-per-hour format. They wanted to keep the Radar Gun Baseball Pitch Speed Display, but the new score board did not have this option. So they asked REA TECHNOLOGIES,INC if we could design and build a Radar Gun interface based around their original Radar Gun, TRIAC Driver PCB, and Light Bulb Panel. They also stipulated that they wanted to use fiber optic communications from the Radar Gun to the Light Bulb Panel.

I started out by studying the communications format of the Radar Gun. I found that its protocol was RS232. I wrote a Microsoft Visual Basic program so that I could display the output of the Radar Gun communications on a Computer Monitor. We found that when a ball was thrown towards the Radar Gun, it would display the speed as 00045. This would translate to 45mph.

I then reverse engineered the Light Bulb Panel and the TRIAC Driver PCB. This was done so that I could design the Hardware Interface PCB for these two units. When the research was done, I designed the Hardware Interface PCB around the Microchip PIC16F876 microcontroller. I chose this microcontroller because it supports the RS232 communications protocol and had plenty of program memory for this application. Once the hardware was designed and built, I started working on the microcontroller program code. The program code translates the Radar Gun's acquired speed (for example,00045) to the patterns required to fire the correct TRIACS to turn on the light bulbs and display the baseball's pitch speed (for example 045). The code has garbage collection routines written so that spurious data does not get displayed on the Light Bulb Panel.

Lastly, I built an RS232 to Fiber Optic Converter so that we could transmit the Radar Gun's output to the Hardware Interface PCB. The fiber-optic cable runs underground around the perimeter of the ball field, so I had to choose fiber-optic transmitters and receivers that would go the distance. This was crucial because signal degradation would occur if the transmitters and receivers signal distance parameters were less than the required distance. And thus corrupting the communication signal.

When we got the hardware installed at the ball field and fired it up, it was tested with a few good throws across home plate. Good Good.

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