[Dr_C2]

As mentioned, I hope this will be a simple project to complete.


The approach is as follows:

1/ Two ID sensors will be positioned on each of two lanes with a known separation.

2/ A sensor hub using firmware which has already been developed will read the arrival time at each sensor, plus the car’s ID. IDs are in the range 1-36.

3/ From this information, the transit speed and ID can then be displayed as cars traverse the dual sensor zone.

4/ As mentioned the plan here is to use 100mm tall (4 inch) 7 segment displays. Two digits for ID and then four digits for speed in m/s in the format ‘ZZ.ZZ’.

So all that is left to complete this project is the design and construction of the display modules. 

I will be using a simple ‘clocked serial data’ approach which is fairly standard. This approach typically uses a 74HC596 or if higher current drive is required then a TPIC5D596. I will be using the latter.

This has become a nice little high school grade project :)

A simple test set-up is shown below. The red dual display is a low cost commercial product. The small white display uses one of my PCB designs, and the large green display is using stand-alone TPIC5D596 driver board. I will design a simple back-plane PCB for these large displays to keep wiring looms to a minimum.

   

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