Zero pin output current?

Hochberger

Hi.
I need your help. Yesterday I was working on my project. For circuit testing I use prop DEMO BOARD. Everything worked just fine but suddenly without any reason my circuit stopped working. I tried to re-plug everything - no success. So I decided to measure all voltages and figured out that there is no voltage drop on any resistor.

How it is possible???

For me the only explanation is that voltage is OK but I/O pins providing zero current!!! I have can write spin to EEPROM so I think there could be some burnt circuit directly on DEMO BOARD.

Thanks for everybody's help

Heater.

Hochberger,

suddenly without any reason my circuit stopped working

Now you know in your heart that this is not likely to be true. As a young engineer, when things went badly wrong, my boss would turn to me and say "what did you do last". Why he picked on me I don't know:)

How it is possible???

A million reasons. Now seriously to get any help with this we need a lot more information. Like the schematics and the code and an idea of what it is you are actually trying to do.

Hochberger

Thanks for your reply!

OK, the only thing I did was that I turned my lamp on (same 230V plug as PROP power supply) but I didn't see the relation. I wasn't working with circuit at that failure moment I was just turning my lamp on. Circuit was running and after turning lamp on suddenly stopped

I'm at work now so I can't post schematics. I'm controlling solenoid from P0 connected through adequate resistor to transistor BASE. EMITTER to ground.COLLECTOR: 12 V Solenoid with par. flywheel diode powered with 12V DC. Circuit worked fine for about a week so I don't think there is the problem.

Hochberger

I attached schematics of my circuit. I believe it is correctly designed because it was working for about week.

I'm not sure now what is the exact value of R1 but it is somewhere about 1k0. The solenoid is 12V 5.5W.

Again briefly on my problem. I tried to measure voltage drop on R1 and it shows 0V. P0 provides 3.3V but no current coming out, I think. Resistor is fine, I tried to change it but without result. 12 V supply is OK too.

I think that there is problem with chip or with grounding but I don't know how to figure it out.

You are pros here so I hope that there will be any suggestion how to fix it.

Thank you very much

Mike Green

What program are you using? Your circuit diagram looks fine.

Remember that an I/O pin that is set to input mode will have a high impedance (megaOhms) and will not have a well defined voltage. An I/O pin set to output low will, of course, show zero voltage.

Hochberger

Thanks for reply.
There is absolutely no problem with my code. I was using it for a week as I wrote above - without problem. I used very simple PWM code but after the problem occured I also tried just to make P0 as OUT and set it to HIGH. Voltage between P0 and GND is 3.3V but also "after R1 - GND" There should be about 2.6V drop on R1 so it should show about 0.7V to saturate the transistor. So there isn't problem.

Phil Pilgrim (PhiPi)

You might check for a short between the transistor's base and emitter.

-Phil

Pence128

The emitter or base of your transistor has opened. replace it.

Publison

Can you blink an LED from the pin? If not, Try

CON
  _CLKMODE  =  RCSLOW

for the clock setting. Your PLL may be fried.

Martin Hodge

Is the lamp ballasted (flourescent)? I once fried an SX, SX key and $60 GPS module by switching an OttLite plugged into the same mains socket.

kwinn

The first thing to do is to verify the prop is running by downloading a program to it. This should be a very simple program that toggles a pin once or twice a second. then place a led with a current limiting resistor on that pin to see if the led blinks. If you can download the program you have verified that the prop is detected and running,. If the led blinks you have verified the I/O works.