The crossing signal is a simple implementation using the PCA9635 LED driver.  Using the PWM signal from the PCA9635, you can control the brightness of the LED.  Using a resistor in series with the LED allows you to set the duty cycle to 100% (full brighness), without worrying about burning out the LED's.  

Basic instructions:

1. Hardware:

   • Crossing signal [click here]

   • PCA9635 LED driver [click here]

2. Datasheets:

   • PCA9635 datasheet [click here]

3. Schematic:  [click here]; Note:  This will be the same schematic for the motor driver, except that the motor driver will have a L298N added to it.  Also, it may look better if you download the image to your computer, then open it with your favorite picture viewer.

4. The LED's in the [crossing signal] probably have 1.7 forward voltage with 20 ma max current.  If you're using different LED's, here's are two online LED resistor calculators.  The second one has a section for parallel LED's which is how the LED's are wired in the [crossing signal]:

   • Digi-Key online resistor calculator: [click here]

   • LEDZ online resistor calculator: [click here]

5. Software: [click here]

There's a utility program in the driver examples, but it does not control the OE pin on the txs0108e, so you'll need to set it manually before running the utility program.