Doubt with microcontroller connection.

[Eraser]

microcontroller connection

Hello.

Im doing a project that connects a xbee with one microcontroller(pic16f88), now my doubt is if i connect the tx pin from xbee, with rx pin from pic directly, like the following image, the pic will receive the byte without erros? because the voltage in transmisons will be 3,3V and the pic works with 5V.


Regards.

 

[pakitos]

what i the question?

 

[Eraser]

what i the question?

The question is, if the pic will receive the information correctly, because the pic works with TTL, and xbee send 3,3V.

 

[nandhu015]

It is not advisable to do so.


Nandhu

 

[Eraser]

It is not advisable to do so.


Nandhu

And what is the best way to connect tx from xbee with microcontroller RX??

 

[pakitos]

I do not know why Nandu said so
but concerning the voltage the pic will accept the 3.3v as high.

If the Iout of the device < Iin of the pic no damage will happen. Which I think is the case.

give it a try

 

[Eraser]

I do not know why Nandu said so
but concerning the voltage the pic will accept the 3.3v as high.

If the Iout of the device < Iin of the pic no damage will happen. Which I think is the case.

give it a try

Thanks.i will try.

 

[nandhu015]

I do not know why Nandu said so
but concerning the voltage the pic will accept the 3.3v as high.

If the Iout of the device < Iin of the pic no damage will happen. Which I think is the case.

give it a try

does the zigbee can handle 5v at its input?

I personally will use a level convertor

Nandhu

 

[pakitos]

he is going to use the zigbee as input to microcontroller not the microcontroller input to zigbee Right?

 

[Eraser]

he is going to use the zigbee as input to microcontroller not the microcontroller input to zigbee Right?

Thats it, to micro-xbee i use the resistors.

 

[pakitos]

Ok let me guide you.

for the pic as TX you have used resistors.. These resistors will lower the voltage comming out of pic( 5V) to a lower level which can be handeled by Xbee.

As for the pic working as RX:
check first if the pic is considering the 3.3 voltage as high (simple test). ( I think it should)
If the pic is not receiving correctly, what you can do is use a transistor as switch bw xbee and pic

 

[Eraser]

Ok let me guide you.

for the pic as TX you have used resistors.. These resistors will lower the voltage comming out of pic( 5V) to a lower level which can be handeled by Xbee.

As for the pic working as RX:
check first if the pic is considering the 3.3 voltage as high (simple test). ( I think it should)
If the pic is not receiving correctly, what you can do is use a transistor as switch bw xbee and pic

thanks.Any more boubt i post .

 

[marcelino]

its the resistor!!! why din't i think of this...
tsk tsk tsk, i just broke one module! there should be a resistor...

so what are the typical values for resistor?

 

[Eraser]

There are not tipical resistors values, just make sure the resistors values are above 1kohm, because for values below 1k the current generated could be elevated, and damage the xbee. The voltage max. in xbee is 3,3V so you have to calculate the resistors. But in my post there are an image, 10k and 20k, for 5V.