Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: katherina on November 25, 2007, 08:42:14 PM

Title: NO OUTPUT (VOLTAGE DROP) AT OUTPUT PIN
Post by: katherina on November 25, 2007, 08:42:14 PM

hi... i'm currently working on climbing robot, rite now, i've built the hardware and the circuit is done too.
however, there is no voltage drop at the output pin, n i wonder why is dat so?
because we have detected that the input pin is working, with 5v supply... but, it does not produce any output...  where could be the problem be? ???
 tq

Title: Re: NO OUTPUT (VOLTAGE DROP) AT OUTPUT PIN
Post by: ed1380 on November 25, 2007, 08:47:36 PM

I'm not really getting you.

if there is no output there could be a lot of different problems. it was programmed wrong, soldered wrong, etc.

could you be more specific

Title: Re: NO OUTPUT (VOLTAGE DROP) AT OUTPUT PIN
Post by: katherina on November 25, 2007, 08:50:44 PM

i think the programming is correct....  there might be some electronics problem... but i dunno where the probkem could be...

Title: Re: NO OUTPUT (VOLTAGE DROP) AT OUTPUT PIN
Post by: ed1380 on November 25, 2007, 08:52:30 PM

I'd take a multimeter and test the connections. also check that there are no shorts

Title: Re: NO OUTPUT (VOLTAGE DROP) AT OUTPUT PIN
Post by: katherina on November 25, 2007, 08:53:14 PM

soldering?
 i have check the crystal connection, etc... can't find where it is wrong.

usually, where could be the problem if there are no outputs at the pin of PIC 16F877A?

becoz there is input(voltage of 5V) at the input pin of the chip.

Title: Re: NO OUTPUT (VOLTAGE DROP) AT OUTPUT PIN
Post by: katherina on November 25, 2007, 08:54:35 PM

ok... tq, may i know which part to test? at the PIC???

Title: Re: NO OUTPUT (VOLTAGE DROP) AT OUTPUT PIN
Post by: ed1380 on November 25, 2007, 08:56:35 PM

I'd start at the output pin that doesnt work

Title: Re: NO OUTPUT (VOLTAGE DROP) AT OUTPUT PIN
Post by: paulstreats on November 25, 2007, 09:04:53 PM

which pin is it? e.g rb1

Title: Re: NO OUTPUT (VOLTAGE DROP) AT OUTPUT PIN
Post by: jsmoker on November 26, 2007, 08:04:26 AM

yeah, you need to give a lot more information.  What kind of micro controller are you using?  When you say there's 5V at on the input pin, do you mean the Vcc/Vdd?  is your ground connected properly (Vss).  Some micro controllers are finicky about writing to the "latch" instead of the "port".   Are you sure that the "port" operation is primary.  Often times certain leads can double as a UART or SPI, etc so you have to make sure it's set to be a digital output first.  If you have a schematic of your circuit that you help greatly, too.  Even an MS Paint drawing would help.