Thank you again for your additional help
. There is a layout updated with text on the dropbox:
https://dl.dropbox.com/u/95408065/Raspb ... g_V0p3.png
I use most components as suggested on your board (2N7000, IRF9Z34N, IRLZ24N, Zenner 3V, 500mw). I also tried the circuit on my breadboard and H-Bridges work very well.
I have some questions about the input Part:
Somehow I read in your documentation it’s ok to use R2 = 100K with a Z-Diode instead of R1.
If I try this on my bread board I get only 1,7V at GPIO, using 12V at the Sensor. I substitute R2 with 1K and using 12V Sensor Input I get 3,3V as I wish. Using a 220k Pull-Down makes no difference in both cases. I’m not sure jet about the sensors I will connect. Could be 5V or 12V. Maybe I need to make R2 changeable?
My thoughts about the R2 dimensions:
Using: 1k Resister (R2), 12V Sensorvoltage and max. 500mW allowed for the Zener-Diode
- > 12mA -> 12V x 12mA = 144mW
Questions1: Is 1K in principle ok (means are my calculations ok?)?
About the GPIO voltage needed:
Using 5V as Sensor Input I only get 2,6V at the GPIO.
Question 2: Are 2,6V enough to get a “True” at the Raspberry GPIO
I also have a question about the ground connection.
Is it fine, to connect ground from Raspberry with Ground from 12V power supply from the platine? Is there any protection necessary to prevent current caused by different ground levels?
Thanks alot in advance