does this Ckt work? Does LED will glow?

[kil]

does this Ckt work

Hi,

in the attched CKT i am giving vcc as 3.3V driving the latched Input/Output pin and form latched pin i am connected as shown in the figure attached. but does this LED glow?

Since at the Anode side is connected to 3.3V and the Cathode side is also connectd to 3.3v thorugh 510ohms.




Thanks
Kil

 

[kamalkiran.j]

does this Ckt work

hi
i think the above shown circuit do not work as u say that both the terminals are at same potential , and there is no Flow of current through LED , and thus the LED will not GLOW..

 

[laktronics]

Re: does this Ckt work

Hi,
LED will definitely glow when latched I/O goes low.
Regards,
Laktronics

 

[ilikebbs]

does this Ckt work

I agree with Laktronics.

But why do you want to use R27??
It is unreasonable.

 

[kil]

Re: does this Ckt work

Hi,

I Think R27 is kept so that PIN will not recieve high current it may damage the PINit will just resist high current flow.

latched I/O is pulled low by using the register setting right if it is pulled low then at pin it will be having low voltage... is it correct

Regards
KIL

 

[laktronics]

Re: does this Ckt work

Hi,

latched I/O is pulled low by using the register setting right if it is pulled low then at pin it will be having low voltage... is it correct

Yes, You are right. The R27 resistor is an external pullup which will be useful if you are sourcing an external current when the port pin is high. In your application, the port bit need to sink the LED current and in this case, R27 is not required, it only adds to the current to be sunk by the port pin when low.

Regards,
Laktronics