XBee Series 1 Problem

My project is simple.

Atmega16 (1) sends 0xAA to Atmega16 (2) via UART.
Atmega16 (2) sends increment 1 every second to Atmega 16 (1) via UART. (binary addition on LEDs)
(output is on LEDs)

Note: Im not using my PC or laptop to send any data


Both connected with coaxial cable (Tx (1) with Rx (2) , Rx (1) with Tx (2) ) , the project works fine.

Now i wanted to do this project wirelessly using XBee series 1 connected with Parallax Xbee USB adapter board and Parallax Xbee adapter board.
(I have my XBee series 1 on Xbee Adapter Board while the other Xbee is on the USB Adapter Board)

Xbee Series 1 :
**broken link removed**

Xbee Adapter Board :
**broken link removed**

Xbee USB Adapter Board :
**broken link removed**


After spending days and hours trying to get it to work, i reached something weird. And i really need an explanation and a solution for this.


The project works fine but for only ONE condition (other than this condition it doesnt work! (confusing))

This is the conidition:


>Both Microcontrollers are getting their power from a 5V Adapter.
>Both Xbees MUST be getting their power from USB to send/receive the data.
If the Xbee on the Xbee Adapter board gets its power (VDD pin) from the 5V Adapter it doesnt work (its powered on (power LED is on) but it doesnt transmit the data).
If the Xbee on the USB Adapter board's VSS pin connected to ground (gnd of 5V Adapter) its powered on WITHOUT connecting VDD pin to anything and WITHOUT USB power (i do not know how its working like that) . And if i connect the VDD to (5V Adapter) it turns off.

Still there is another problem.
Lets say we went along with this condition. So i Connect the Xbee Adapter board power from a USB port (5v and gnd only from the PORT) , and the USB Adapter board connected with the USB (port built in the adapter) to get its power.

And the microcontrollers are connected to the 5V Adapter.

Now we applied the condition and it works. However...
Logically if you just swap the Atmega16's with each other , the outputs on the LEDs will swap right?
Unfortunately no, i get on one side another output, and on the other side the same old output as if i did not swap anything. (in other words , it did not work).

Both Xbees @ baud rate 19200
Both Microcontrollers' UART @ baud rate 19200


*My Adapter*
5V , 0.7A
>Last time (less than 24 hours ago) i checked the 5V Adapter , it gave a reading of ~5.03V

>All my work is on 5V so im not getting near 3.3V (VCC)

>I configured the Xbees with X-CTU and tested them with the terminal function and a loop back connection and it worked fine (both from USB power). (so there is nothing wrong with my Xbee's i guess).

When i connect the microcontroller (getting its VDD from 5V Adapter) with the Xbee and loop back xbee (i did this so that whatever the microcontroller is transmitting should be looped back and outputted on LED), i get nothing on the LEDs.

If there is a problem with my adapter (i do not know why there would be , its working fine) , please tell me what i should use instead of using USB power.

I know i rote a lot but i need a solution,
Even if we managed to fix one problem from all this that would be great.
I cannot keep using the Xbees with the USB as they will be on robots later on.

I can re-connect my project all over again step by step if this would help find the problem and start troubleshooting with anyone.

Your problem is supply of XBee.
give 3.3 V to XBee and it will get solved.

Jigar 4 Electronics said:

Your problem is supply of XBee.
give 3.3 V to XBee and it will get solved.

Click to expand...

Sorry for the late reply, i went to buy some components to make a 3.3V regulator circuit and it worked! I connected the 3.3V output with the VCC pins of the Xbees and it worked. Now i do not need to use USB power. Thank you Jigar 4 Electronics.

However, swapping the microcontroller problem still exists..(This is the last problem)
I will remind you about it again

>>Project:
Atmega16 (1) sends 0xAA to Atmega16 (2) via UART.
Atmega16 (2) sends increment 1 every second to Atmega 16 (1) via UART. (binary addition on LEDs)
(output is on LEDs)

>>After swapping Atmega's:
If you just swap the Atmega16's with each other (without changing any other connection on the board), the outputs on the LEDs will swap right?
Unfortunately no, i get on Atmega (1) 0xAA , and on Atmega (2) output changes between 0xAA and 0x55 constantly. Weirdly when i turn off the Xbees but the Atmega's are still on , Atmega (1) still gets an output of 0xAA and Atmega (2) some random data. Any solution?

Are there any other tests i could make to help figure out the problem?

and Thank you again for your help.

AdilAli said:

swapping the microcontroller problem still exists

Click to expand...

For that you should post your schematic & code which you've used on both the sides.
without knowing what & how you're doing that, we're unable to say anything.