HI…since I’m do not have much experience in designing circuit boards I have come accross a problem that I can’t figure out.
I have a Pic16f88 running on 5+ vdc and I have a sensor that needs 9+ vdc. The output of the sensor (5+vd) connects to an input on the Pic but since the sensor requires the 9+ Vdc, I’m having trouble figuring out how to connect the ground from the 9+ vdc sensor to the Pic. I have tried just connecting the ground directly to the Pic ground, but that seems to effect the Pic and or sensor because the data from the sensor is just garbage.
Are you sure the sensor is sending garbage? Another way to ask would be: are you sure the PIC is reading the data correctly?
Unless your sensor introduces some major noise into the system, or your sensor has some very unorthodox circuitry, you should be able to use the typical ‘common ground’ setup (or whatever it’s called).
Found the problem, it was a bad solder joint…I had to go thru and re-solder all. But I do have another question … what is the best way to stop or elimate noise coming from a senor… it jumps around quite a bit.
If you are using an ADC you need to pay a lot of attention to your PCB layout. It often helps to read the ADC with the MCU in Sleep mode, some PICs allow this.