Problem with RX line

Hi!! I have a problem using an XBee with a PIC 16F876, the problem is that I try to wake up the pic using the RX line, when the module receive a RF paquet, it is send trough the UART to the PIC, the line is with pull-up resistor when there is no data, so when the module sends the received packet to the PIC, the PIC detects the first ‘0’ and wakes up. This is the theory, but when I sleep the PIC, it wakes up inmediately, like data from the XBee is coming all time. I tried without the XBee and with a pull-up resistor, and the PIC works ok when I force the line to ‘0’, the PIC wakes up and all is ok, but if i do it connected to the TX line of the XBee the PIC wakes up inmediately, so any ‘0’ must be on the line. ¿Are the XBee sending any data? ¿How can I avoid it?


I had the same problem using the PIC 16F887 that was programmed using PicBasic Pro. I have not found a fix yet.

Hello everybody

I work in comunication between XBEE devices (version 1) I use different types of PIC micros, 12F families, 16F families and 18F families and I program over CCS PIC-C Compiler(PCWHD 4.06).

Now I have some problems, In general the API commands work fine, except the API commands for remote command set or query, the papers of digi has a poor information about the API commands and no more papers for dig.
All the above works in X-CTU for a host Xbee device and one PCB with PIC12F675 & PIC16F88 send data through Xbee to host (Baud rate at 57600 bps).

When I used a PIC18F4520 for receive data from Xbee host, the Xbee data is corrupted, the expected number of data are received, but each data is wrong!!!

The PIC and Xbee are supplied by 3.3V from a LF33CV LDO regulator. The input voltage for LF33 is supplied for a 7805C 5V regulator, using a scope, I’ve seen a ripple voltage around the 0.5Vpk-pk, and I think this is a serious problem, I need to elminate this ripple. Maybe this ripple affects the receiver data integrity.

In other hand, using pins and jumpers I can configure the use of PIC UART of the MAX232 or a PC serial port( Note this, de MAX232 use a 5V power supply) and remember The above, This method is working.

About programming I been using more than one interrupts, for serial receiver, for external pin change, for change in port, and sofware uarts.

I have so interested in share code.

please send me your commensts and questions to

Users of PIC micro, maybe we can develope together a better interfaces to Xbee!!!.


Hi again. The 16F887 can wake up from an rx interrupt? The 16F876 cant do it, so I need to connect the RX line to the RB0 pin. Anybody knows a 16FXXX pic that wakes up from an rx interrupt?
The XBee manual specifies the received frames:
“Receive Data Frames (sent out the DO pin (pin 2)) include:
• RF-received data frame
• Command response
• Event notifications such as reset, associate, disassociate, etc.”
I think it is an event notification, the solution maybe disable this notifications.

Hi all:

I am a new user for PIC and i am trying to communicate my PIC16F877 with XBee unit. Do you all have any idea on what types of header files I need to include if I am using PCWH C Compiler?

If I need to send data, what type of command should I use?

Thank you.

Hi, I use assembler language, so I cant help you. You can look for in the microchip forums: