Voltage divider part 2

-------------- And if LD111 can be used, then how ? If i have 5V output from arduino should i connect just two capacitors on the LD111 ?

First guess would be it needs more current. You don't give us much info.

NT

Okay, so the RSP needs 3V to trigger.

For a 2k series R from the source and a 1k paralleled with the trigger input, you need a 10V trigger signal.

For a 10k series R from the source and a 1k paralleled with the trigger input, you need a 33V trigger signal.

Both of these estimates do not include pin loading. Is your pin set for high impedance?

What is your trigger source voltage?

how long are your trigger impulses? is the voltage divider frequency compensated?

------------------- I think that the main problem is noise because i have tested bunch of situations ( long , short impulses ) and as long as the wire is connected from arduino to rsp, i get some problems. If i disconnet this wire everything is ok and i dont get any problems.

For now, im using 3,3v zener diode but i have try with resistors and tommorrow i will try with LM111 (3,3V ) voltage regulator.

Anyhow, there must be some short impulse that triggers this state..

Can i filter it somehow ?

GM

Your post makes almost no sense. How about answering the questions to you that have been posted?

Do you have a 'scope? A schematic or picture of what you are doing might help.

George H.

------------------ Unfortunately i dont have a scope but there must be some voltage glitch because it happens only when i connect arduino pin with raspberry pin. Most funny part is that i can't detect any voltage change on multimeter, so it must be some really fast glitch. I tested with my program, with some standard example program and with program for testing raspberry PIN's but it look like that the situation is the same.

Yes, it doesn't make much sense but maybe there is GND problem. Should i connect raspberry GND with arduino GND ?

if you intend for the raspberry to make any sense of a voltage from the arduino yes...

-Lasse

---------------- I will try it. The power supply is galvanic separated so, connecting gnd should do the trick.

Plugging (and unplugging!) stuff together, makes sparks/ current surges... your input circuit has to deal with that. there are all sorts of power on/ slow start... power circuits. If it's a communication line then have the software wait till it's checked the power is good... or a long delay.

George H.