Digital logic VHDL traffic controller

Due to a number of requests for info on the VHDL traffic light controller video on youTube, I thought I would post a quick write up.

"In college my Junior year lab included a project to construct a simple traffic light controller using only digital logic. This means no microcontroller, no 'if' statements nothing but pure hardcore logic. The intent of the lab was to implement a state machine in a realistic application. This article is a collection of pictures and a very general explanation of my solution, plus a VHDL implementation of it."

If you are interested in digital logic or VHDL, take a look.


Joakim Olsson on Feb 24th, 2008 8:32am
Love this.
We did something similar but with a Mitsubishi PLC
when i went to school.
Daniel on Feb 24th, 2008 10:39am
So if its all logic, are all the gates programmed into that one IC?
s1axter on Feb 24th, 2008 11:10am
Yes, CPLDs are Complex Programmable Logic Devices, you can change the physical properties of the hardware inside. Thus you can implement almost any digital logic, even a CPU.

Check out these links:
Max on Feb 24th, 2008 4:31pm
Very cool project! I have been trying to teach myself digital logic over the past year or so. CPLD's look really cool. Any recommendation on which brands to look into?
Max on Feb 24th, 2008 5:29pm
Also, I am curious as to why you went with VHDL over Verilog?
s1axter on Feb 25th, 2008 8:42am
The CPLD is a Coolrunner II from Xilinx on a dev board from Digilent ( The reason it was put on a CPLD with VHDL was as an example to student for the following year as I was the TA for the course.
salam on Nov 22nd, 2008 11:39am
thank you