Low port output voltage problem ??

[skarthikshines]

hi am using msp430f2618 controller i made my own pcb now the problem is if am setting my P1.5 as a output port means am getting only 2.68v on that pin since my vcc is3.22v only.and i did t connect any pull up resistor on that pin...?? and am getting the same problem for other port pins also???

how can i rectify this problem??

 

[cameo_2007]

I think you are only setting it as output. Are you driving that output pin to Logic HIGH? If not you must be measuring a floating output.

 

[skarthikshines]

ya am only making the logic to high . but the problem is the as per data sheet the high level output voltage should be (vcc-0.2)v .vcc=3.25v. so the minimum output should be 3v but am getting only 2.6v

 

[cameo_2007]

is that output pin connected to somewhere? Is there any configuration settings while programming to set the Output levels to certain voltages?

 

[skarthikshines]

is that output pin connected to somewhere? Is there any configuration settings while programming to set the Output levels to certain voltages?

no nothing is like that ..that pin is did t connected to any where??

 

[:pH]

is there an internal pull up available in the controller you have specified ?

 

[skarthikshines]

is there an internal pull up available in the controller you have specified ?

ya there. i tried by enabling and disabling the pull up.but am getting same error.

 

[:pH]

well then may be , there is some kind of problem in the PCB

 

[cameo_2007]

Tried with a different IC?

 

[skarthikshines]

if i test the same ic by de-soldering the and placed in my ic socket means the port pins are working properly.. so now i found that the problem is in my pcb.. can you say what kind of the possibilities to reduce the port pin voltage ?? so it would help me to trouble shout my pcb??

 

[:pH]

Once a pcb is constructed , i doubt you can do anythng now . . . Recreate the pcb

 

[alexan_e]

no nothing is like that ..that pin is did t connected to any where??

That doesn't make much sense.
You have a pin that is connected to nowhere and you are interested for the voltage it has?
Isn't there a PCB track starting from the pin and going to some other point?
Use a magnifying glass and check if you have some kind of short in the pins.
Also some times solder paste residue may cause problems.

Alex

 

[skarthikshines]

initially i got this problem in the pin which is connected to the external DAC.. so i thought to check the unconnected pin

i.e here i connected port 4 and port 5 to the external DAC and port 1 is un connected to any where..
i am getting the same problem in all the port pin

 

[cameo_2007]

Once a pcb is constructed , i doubt you can do anythng now . . . Recreate the pcb

I dont beleive that. There are still ways, you can always make modifications on the board if it is possible.
Atleast you should figure out what the problem is, before blindly re-manufacturing the board.

---------- Post added at 14:09 ---------- Previous post was at 13:59 ----------

if i test the same ic by de-soldering the and placed in my ic socket means the port pins are working properly.. so now i found that the problem is in my pcb.. can you say what kind of the possibilities to reduce the port pin voltage ?? so it would help me to trouble shout my pcb??

Possibilities:

1. IC gone bad
2. Programming methods. Low voltage configurations? ( but you said it works on socket.By the way,What exactly do you mean by socket? )
3. The pin is connected to some point where it is not supposed to be connected.And that may be loading the IC and causing the voltage to drop.

Check, double check the layout of those pins. Follow where the tracks are going from that pin. That is the only way now i guess.

Get here the layout file if possible.

 

[skarthikshines]

now i found that mistakes if i tie my analog reference gnd that is VREF/Ve REF- pin number 11 in msp430f2618 TO gnd am getting voltage reduction on my port.. but as per data sheet in order to use external analog reference for ADC operation i need to tie that pin to gnd.. so what is the problem here??

 

[cameo_2007]

now i found that mistakes if i tie my analog reference gnd that is VREF/Ve REF- pin number 11 in msp430f2618 TO gnd am getting voltage reduction on my port..

Are you sure about that is causing the problem. Because I dont see an issue with that. May be I am wrong at this moment.