Hello guys. I need help. I want to pixelblaze receive analogs signals using the output expander module and do some patterns when those inputs get apply. Like movement flood for turn signal, white or any color to select for DRL, Flash 4 times and then stay on for brake and others things. Ok. My question is. Can somebody here with the experience and knowledge about the pixelblaze can do this for me?
Automotive voltages vary, and are usually higher than “12V” and are upwards of 14.7V when charging, and could be momentarily higher. The signals are also not “clean” and often have some noise.
I would use 10K on the low side, and 40K on the high side. That will give you 3V out with 15V in, and 2.4V out (still high enough to read) with 12V in.
In addition to this, you could add some protection circuitry, such as a diode from the divider output to the 3.3v supply on the sensor board. This would prevent higher voltages from shooting above 3.3v.
For even better/safer results, use an optoisolator / optocoupler like this (but with 3.3v instead of 5V):